Adjustment and compensation of cotton to physical damage at early squaring stage
LU He-Quan1,*, QI Jie2,*, DAI Jian-Long1,*, ZHANG Yan-Jun1, KONG Xiang-Qiang1, LI Zhen-Huai1, LI Wei-Jiang1, XU Shi-Zhen1, TANG Wei1, ZHANG Dong-Mei1, LUO Zhen1, XIN Cheng-Song1, SUN Xue-Zhen2, DONG He-Zhong1,2,*通讯作者:
收稿日期:2018-10-17接受日期:2019-01-12网络出版日期:2019-02-19
| 基金资助: |
Received:2018-10-17Accepted:2019-01-12Online:2019-02-19
| Fund supported: |
作者简介 About authors
卢合全,E-mail:
祁杰,E-mail:
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卢合全, 祁杰, 代建龙, 张艳军, 孔祥强, 李振怀, 李维江, 徐士振, 唐薇, 张冬梅, 罗振, 辛承松, 孙学振, 董合忠. 棉花对初蕾期物理伤害的调节补偿效应[J]. 作物学报, 2019, 45(6): 904-911. doi:10.3724/SP.J.1006.2019.84131
LU He-Quan, QI Jie, DAI Jian-Long, ZHANG Yan-Jun, KONG Xiang-Qiang, LI Zhen-Huai, LI Wei-Jiang, XU Shi-Zhen, TANG Wei, ZHANG Dong-Mei, LUO Zhen, XIN Cheng-Song, SUN Xue-Zhen, DONG He-Zhong.
棉花(Gossypium hirsutium L.)具有无限生长习性, 自身调节补偿能力强。这种自身调节和补偿能力一方面表现在对密度[1,2]、播期[3,4]、整枝[5,6,7]、施肥[8,9,10,11]等农艺措施具有较强的适应能力, 另一方面表现在对逆境胁迫[12,13,14]和物理伤害[15,16,17,18,19,20,21,22]的忍耐和恢复补偿能力。前人通过摘除早期幼蕾或去叶片模拟虫害造成的物理损伤, 对棉花的补偿能力及其机理作了较为细致的研究。Bednarz等[18]研究发现, 随摘除早期蕾数量的增多, 下部冠层分布的铃减少, 而上部和外围分布的铃增多; Pettigrew等[19]和Stewart等[20]研究表明, 摘除果枝上的早期幼蕾, 能提高其他果枝节位的成铃率; Kerby等[21]发现果枝第一节位的幼蕾脱落后, 第二节位的成铃率提高17%~33%; Kletter等[22]和Kerns等[23]研究发现, 摘除早期蕾显著提高了生育后期的成铃率, 棉花单株铃数和产量与未摘除早蕾的对照相比无明显差异。Mo等[24]通过去主茎叶模拟蓟马对棉苗的危害, 发现去除75%叶片对棉花产量不会产生影响。本实验室以前对去早果枝的研究表明[6-7,25], 去除2个早果枝能够调节库源关系并延缓后期叶片衰老, 对棉花产量的形成没有不利影响。上述研究表明, 在叶片光合器官或棉株体没有严重损伤时, 只要开花结铃时间充足, 遭受物理损伤的棉花基本不会减产, 显示出超强的自身调节和补偿能力。
雹灾发生后, 棉花的茎枝叶易受到物理损伤, 严重时主茎顶心也会受到影响, 甚至“断头”[26,27,28]。通过对苗期和蕾期受雹灾危害程度不同的棉田定点调查发现, 受灾程度越重, 棉株生长恢复越慢, 秋桃和晚秋桃数量增多, 减产幅度增大[27,28]。当棉花苗期叶片全部去掉时, 棉花的生育进程推迟, 结铃吐絮延后, 单位面积铃数和铃重降低, 进而减产[22]。6月上中旬是黄河流域棉区雹灾高发期[29], 此时棉花正处于营养生长与生殖生长并进的蕾期, 主茎顶心损伤影响果枝数量, 叶片损伤则影响光合生产能力, 进而影响产量。目前, 尚少见通过损伤主茎顶心或叶片模拟蕾期雹灾来研究棉花自我调节补偿效应的报道, 这方面的研究对于棉花灾后管理具有实践指导意义。
1 材料与方法
1.1 试验地点
山东棉花研究中心试验站(山东省临清市, 36º68′N, 115º72′E)土壤类型为沙壤土, 试验田中上等地力, pH值7.64, 含有机质12.3 g kg-1、碱解氮48.5 mg kg-1、有效磷28.8 mg kg-1、速效钾166.5 mg kg-1。1.2 试验设计和田间管理
2014—2015年以山东省主栽棉花(Gossypium hirsutium L.)品种K836为材料, 设去顶去叶(去主茎顶心和所有叶片, RTL)、去顶留1叶(去主茎顶心、留1片主茎功能叶, RT+1LM)、去顶留叶(去主茎顶心、保留所有叶片, RT+ALM)、留顶去叶(留主茎顶心、去所有叶, TM+RL)、留顶留1叶(留主茎顶心、留1片主茎功能叶, TM+1LM)、正常植株(CK) 6个处理(图1)。于现蕾后第5天进行损伤处理, 去顶心处理是将第一果枝及以上的冠层(茎、枝、叶)部分全部打掉; 留1叶处理是保留最顶端的1片主茎功能叶。采用随机区组设计, 重复3次。小区面积40 m2, 6行区, 行长8.78 m, 76 cm等行距种植。图1
新窗口打开|下载原图ZIP|生成PPT图1去顶去叶(RTL)、去顶留1叶(RT+1LM)、去顶留所有叶(RT+ALM)、留顶去叶(TM+RL)、留顶留1叶(TM+1LM)及正常植株(CK) 6个处理
Fig. 1Six treatments including removal of main-stem terminal and total leaves (RTL), removal of main-stem terminal but 1 leaf maintained (RT+1LM), removal of main-stem terminal but total leaves maintained (RT+ALM), main-stem terminal maintained but removal of total leaves (TM+RL), main-stem terminal and 1 leaf maintained (TM+1LM), and non-damaged control (CK), respectively
于3月中旬耕地, 4月初浇水造墒。结合播种基施氮磷钾复合肥(25% N, 14% P2O5, 6% K2O) 450 kg hm-2。2014年和2015年分别于4月26日和4月24日按预定密度穴播, 随后覆盖地膜, 同时在地头播种预备苗, 出苗后及时放苗, 及时移栽补苗, 2片真叶后定苗, 密度为52,500株 hm-2。于6月25日对去顶心处理进行整枝, 保留最顶部1个叶枝, 全部处理于7月22日打顶。初花期追施尿素(46% N) 150 kg hm-2和硫酸钾(50% K2O) 30 kg hm-2。在整个生育期均按常规大田棉花管理所有处理。
1.3 试验数据采集与处理
1.3.1 生物量与叶面积 处理后15、30、45和60 DAT取样, 从每小区随机选3株棉花, 用LI-3100C叶面积仪测定单株叶面积, 计算叶面积指数(LAI), 分器官烘干称重。1.3.2 净光合速率 处理后15、30、45、60和75 DAT, 采用便携式光合作用系统测定仪LI-6400 (LI-COR Lincoln, USA)测定净光合速率(Pn), 测定每处理6株, 即6次重复。打顶前测主茎功能叶倒三叶, 打顶后测主茎倒二叶。
1.3.3 产量与产量结构 吐絮后分4次对每小区中间4行收获籽棉, 晒干后称重计产; 每次收花时取50铃, 晾干后称重并计算平均单铃重; 以小区籽棉产量/平均单铃重算得单位面积铃数。
1.3.4 棉柴比与早熟性测定 在收花结束后, 将每小区中间两行棉株于子叶节处剪断, 晾晒30 d后称重。以籽棉与棉柴重量之和作为其近似的生物产量, 以两者的重量比(棉柴比)作为光合产物分配情况和经济系数的指标; 以霜前收获的籽棉与总籽棉重量的比值(%), 即霜前花率, 作为早熟性的指标。
1.4 统计分析
用Microsoft Excel 2003软件计算数据和作图, 用DPS 7.05统计分析软件检验数据差异显著性。2 结果与分析
2.1 物理损伤对棉花动态生物量积累的影响
处理后30 d, 各处理的生物量均呈快速增长趋势, TM+1LM的生物量与CK相当, 且明显高于其他处理。2014年, 处理后15、30、45和60 DAT, RTL的棉株生物量比同期的CK分别降低88.3%、83.3%、70.1%和60.6%; RT+1LM分别降低61.6%、50.7%、21.6%和18.3%; RT+ALM分别降低23.7%、33.1%、30.8%和12.3%; TM+RL分别降低72.9%、59.9%、48.5%和33.8%; 处理后15 DAT, TM+1LM的生物量较CK降低59.0%, 但30、45和60 DAT的生物量与CK相当。2015年各处理的动态生物量积累与2014年趋势相一致(图2)。说明去顶、去叶均影响棉花生长, 伤害程度不同, 棉株恢复能力也有所不同。图2
新窗口打开|下载原图ZIP|生成PPT图22014-2015年物理损伤对棉花单株生物量积累的影响缩写同
Fig. 2Effects of physical damages on biomass accumulation of cotton in 2014 and 2015
2.2 物理损伤对棉花叶面积指数的影响
60 DAT内, 所有处理的棉花群体叶面积指数(LAI)均随生育进程递增, 处理30 DAT后, TM+1LM的叶面积指数与对照相当, 均高于其他处理。2014年, 15、30、45、60 DAT时, RTL的群体叶面积指数比同期的CK分别降低76.3%、68.7%、66.8%和60.9%; RT+1LM分别降低50.9%、44.4%、31.7%和34.8%; RT+ALM分别降低27.3%、35.4%、18.9%和34.2%; TM+RL分别降低63.6%、55.6%、47.8%和33.9%; 15 DAT时, TM+1LM较CK降低了40.0%, 但30、45 DAT的叶面积指数与CK相当, 60 DAT时, 比CK高4.8% (图3)。2015年, 15、30、45和60 DAT时的叶面积指数, RTL群体比同期的CK分别降低72.7%、56.6%、42.8%和26.5%; RT+1LM分别降低45.4%、34.2%、11.4%和18.4%; RT+ALM分别降低22.7%、27.4%、10.7%和7.6%; TM+RL分别降低46.9%、40.0%、21.4%和8.1%; 在15、30和45 DAT, TM+1LM比同期的CK分别降低31.8%、10.3%和5.2%, 但60 DAT时, 叶面积指数与CK相当(图3)。
图3
新窗口打开|下载原图ZIP|生成PPT图32014-2015年物理损伤对棉花群体叶面积指数的影响缩写同
Fig. 3Effects of physical damage treatments on leaf area index (LAI ) of cotton in 2014 and 2015
2.3 物理损伤对棉花净光合速率的影响
去顶、去叶降低了棉花前期的叶片净光合速率(Pn), 推迟了Pn高峰值的出现, TM+1LM处理的Pn变化规律以及峰值出现时间与CK相一致。2014年, 15、30、45 DAT时, RTL的Pn比同期CK分别降低24%、22.4%和31.4%; RT+1LM分别降低23.3%、18.7%和32.1%; RT+ALM分别降低1.3%、16.4%和26.0%; TM+RL分别降低21.3%、25.7%和29.5%; 处理45 DAT后, CK的Pn呈下降趋势, 而RTL、RT+1LM、RT+ALM和TM+RL的Pn仍处在快速增长期, 60 DAT时峰值出现, 且明显高于CK; TM+1LM的Pn变化规律与CK相一致, 于45 DAT时出现峰值, 后逐渐下降。2015年各处理的净光合速率表现与2014年类似(图4)。图4
新窗口打开|下载原图ZIP|生成PPT图42014-2015年物理损伤对棉花净光合速率(Pn)的影响
缩写同
Fig. 4Effects of physical damage on leaf net photosynthetic rate (Pn) of cotton in 2014 and 2015
Abbreviations are the same as those given in
2.4 物理损伤对棉花生物产量和棉柴比的影响
2014年, TM+1LM的最终生物产量与CK差异不显著, RT+1LM和RT+ALM分别比CK高23.2%和11.7%, 而TM+RL比CK减少16.2%; 2015年与2014年的结果趋势基本一致。2年平均, 与CK相比, RTL、RT+1LM、RT+ALM和TM+1LM的生物产量分别增加1.5%、19.0%、13.1%和2.4%, 而TM+RL则减少18.2% (表1)。Table 1
表1
表12014-2015年物理损伤对棉花生物产量和棉柴比的影响
Table 1
| 处理 Treatment | 2014 | 2015 | 平均Average | |||||
|---|---|---|---|---|---|---|---|---|
| 生物产量 Biological yield (kg hm-2) | 棉柴比Seedcotton/ stalk | 生物产量 Biological yield (kg hm-2) | 棉柴比Seedcotton/ stalk | 生物产量 Biological yield (kg hm-2) | 棉柴比Seedcotton/ stalk | |||
| RTL | 9902 cd | 0.33 e | 10158 b | 0.39 d | 10030 b | 0.36 d | ||
| RT+1LM | 12384 a | 0.40 d | 11130 a | 0.42 d | 11757 a | 0.40 d | ||
| RT+ALM | 11229 b | 0.45 c | 11105 a | 0.51 c | 11167 a | 0.48 c | ||
| TM+RL | 8422 d | 0.52 b | 7737 d | 0.65 b | 8079 c | 0.58 b | ||
| TM+1LM | 10100 c | 0.71 a | 10249 b | 0.71 ab | 10114 b | 0.71 a | ||
| CK | 10053 c | 0.72 a | 9699 c | 0.80 a | 9876 b | 0.76 a | ||
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2014年, RTL、RT+1LM、RT+ALM和TM+RL的棉柴比分别比CK降低54.2%、44.4%、37.5%和27.8%; 2015年分别降低51.2%、47.5%、36.2%和18.7%。2年TM+1LM处理的棉柴比均与CK无明显差异(表1)。
2.5 物理损伤对棉花产量和产量构成的影响
由表2可知, 去顶或去所有叶均降低了棉花产量和早熟性, 但留顶留1叶(TM+1LM)处理的籽棉产量变化不明显。2014年, RTL、RT+1LM、RT+ALM和TM+RL较CK分别减产36.3%、17.2%、15.5%和31.9%, 2015年分别减产32.5%、23.1%、13.9%和28.8%, 而TM+1LM的产量均与CK相当。去顶或去所有叶降低了棉花单位面积铃数和单铃重。2014年, RTL、RT+1LM、RT+ALM和TM+RL的铃数较CK分别减少19.0%、7.2%、9.9%和15.6%, 单铃重分别降低23.2%、8.9%、8.9%和19.6%; 2015年铃数分别减少10.3%、4.0%、5.7%和6.0%, 单铃重分别降低25.9%、22.2%、20.4%和16.7%。TM+1LM对铃数和铃重影响则不大。RTL、RT+1LM、RT+ALM、TM+RL和TM+1LM的早熟性较CK均显著降低, 2014年降低幅度分别为41.9%、11.6%、6.6%、36.0%和11.5%, 2015年分别降低27.8%、11.2%、8.2%、17.1%和9.0%。Table 2
表2
表22014-2015年物理损伤对棉花产量、产量结构和早熟性的影响
Table 2
| 处理 Treatment | 2014 | 2015 | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| 籽棉 Seedcotton (kg hm-2) | 铃数 Bolls m-2 | 铃重 Boll weight (g) | 早熟性 Earliness (%) | 籽棉 Seedcotton (kg hm-2) | 铃数 Bolls m-2 | 铃重 Boll weight (g) | 早熟性 Earliness (%) | |||
| RTL | 2646 f | 60.5 e | 4.3 c | 52.5 e | 2907 e | 73.4 d | 4.0 e | 65.8 f | ||
| RT+1LM | 3438 d | 69.4 b | 5.1 b | 79.9 c | 3310 c | 78.5 b | 4.2 d | 80.9 d | ||
| RT+ALM | 3510 c | 67.3 c | 5.1 b | 84.4 b | 3705 b | 77.1 c | 4.3 d | 83.6 b | ||
| TM+RL | 2826 e | 63.1 d | 4.5 c | 57.8 d | 3066 d | 76.9 c | 4.5 c | 75.5 e | ||
| TM+1LM | 4017 ab | 72.6 a | 5.5 a | 80.0 c | 4219 a | 80.7 a | 5.1 b | 82.9 c | ||
| CK | 4152 a | 74.7 a | 5.6 a | 90.4 a | 4306 a | 81.8 a | 5.4 a | 91.1 a | ||
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3 讨论
补偿效应是植物普遍存在的一种适应性生理现象[30,31,32]。作为一年生作物的棉花, 保留了无限生长习性, 现蕾开花持续时间长, 具有较强的自我调节能力, 受损伤的棉花在营养器官和生殖器官水平都会产生补偿反应[15-20,22-23,27-28]。Wilson等[33]在现蕾前通过摘除主茎叶片研究指出, 棉花前期的生长受到不利影响, 随生育进程棉株生长逐渐恢复, 对产量不会造成大的损失。Brook等[17]研究发现, 去掉棉花苗期主茎顶心对产量也不会产生负面影响。李明正等[27]发现, 受雹灾程度越重, 棉花恢复生长阶段生长越慢, 恢复期越长, 随着时间的推进, 棉花生长差异越来越小。本研究发现蕾期去顶、去叶显著影响棉花生长发育, 进而影响产量形成, 这种负面效应以及棉株恢复能力因伤害程度不同而有所不同。需要注意的是, 本研究是基于人工模拟的试验研究, 所得结果与冰雹大风伤害可能会有差异, 实际应用时要考虑这种差异。3.1 对物理损伤的生物产量补偿效应
棉花主茎下部生有叶枝, 将叶枝培养为再生主茎, 叶枝虽不能直接结铃, 但一方面可以作为叶源, 调剂叶面积的不足; 另一方面通过间接结铃, 调剂铃库的不足, 贡献部分经济产量, 表现出中前期增源和中后期扩库的作用, 保障了棉株的自我调节补偿能力[12]。本研究中, 处理60 DAT内, 去除顶心和全部叶片对棉花生物量积累均会产生负面影响, 这与前人的研究一致[17,24,33]。随着棉花再生主茎的建立, 主茎功能叶的形态建成逐渐完备, 净光合速率处在一个快速上升阶段, 基于棉花强的自我补偿能力, 光合产物更多地向营养器官转运, 维持棉株体继续生长, 并最终实现生物量与对照相当, 甚至反超。TM+1LM处理中, 主茎顶的完好保证了后续果枝的正常出现与生长, 剩余的一片主茎功能叶为处理前期的棉花恢复性生长提供所需的光合产物, 发挥其超补偿能力, 从而为后续果枝生长以及生物量的积累奠定基础。该结论与Mo等[24]的研究结果相一致, 当75%棉株去掉叶片或单株棉花去掉75%叶片时, 棉花的株高以及生物量不会受到影响。由此表明, 棉花遭受物理损伤但顶心存在时, 剩余主茎功能叶片对加速棉株恢复性生长发挥重要作用。3.2 对物理损伤的经济产量补偿效应
关于蕾铃脱落后棉花产量补偿方面的研 究[18-23,27-28]表明, 棉花通过增加外围(第三果节及以外)和上部冠层铃数来补偿产量, 只要开花结铃时间充足, 棉花产量基本不降; 但当恢复时间不足以补偿早期蕾铃的损失时则减产。在黄河流域棉区, 10月23日为霜降节气, 8月15日后形成的蕾为无效蕾, 因此, 该区棉花生长发育具有明显的时效性。大量研究指出, 棉花蕾期前因虫害、自然灾害等导致叶片受损, 依靠较强的自我恢复和补偿能力, 几乎不会减产[24,33-34]。叶片损伤会推迟棉花的生育进程, 导致棉铃成熟期推迟, 推后时间随伤害频率和伤害程度加重而延迟[15,17,24,33]。本研究中, RTL、RT+1LM、RT+ALM和TM+RL处理均减产, 这可能一方面是因为主茎顶心去掉后, 受损棉株需培植新的赘芽作为再生主茎, 再生主茎的生长需消耗大量的光合产物, 导致过多的光合产物向茎枝转运, 补偿营养生长, 而减少了向生殖器官的转运量, 导致棉柴比降低, 进而减产; 另一方面, 主茎叶全部去掉后, 棉株前期以恢复叶片光合形态系统为主, 致使净光合速率高峰值后移(60 DAT), 推迟了结铃和吐絮期。在黄河流域棉区, 处理后60 DAT形成的棉铃主要以秋桃为主, 铃重偏小, 导致减产。该结果与Wilson等[33]的研究结论相符, 当棉花叶片持续遭受严重损伤时, 棉铃成熟期推迟, 造成减产。主茎顶心存在且部分叶片受损时, 剩余叶片的光合产物能够维持损伤前期棉花营养生长所需的养分供应, 保证果枝的正常伸展与光合系统的建成, 实现对营养器官和生殖器官的协调补偿, 做到棉柴比适中。处理后45 DAT恰逢伏桃形成高峰期, 前期足够的生物量积累为产量形成打下基础, 净光合速率高峰值的出现则为铃重增加、棉铃正常成熟吐絮提供了保证。固此, 前期足够的生物量积累以及后期持续高效的光合产物供应是实现棉花对物理损伤下棉花经济产量补偿的关键。
物理损伤处理RTL、RT+1LM、RT+ALM和TM+RL的籽棉产量较未损伤的对照分别降低36.3%、17.5%、15.5%和31.9%, 而TM+1LM的铃数和单铃重没有显著降低, 籽棉产量与对照相当。可见棉花蕾期遭遇物理伤害, 会利用自身无限生长习性对经济产量予以补偿, 补偿效果因损伤程度而异。根据产量损失大小, 可以把蕾期物理损伤分为轻度损伤(TM+1LM)、中度损伤(RT+1LM、RT+ALM)和重度损伤(RTL、TM+RL), 其减产幅度分别在5%以内、15%左右和30%以上。对于轻度和中度损伤棉田, 宜加强水肥管理促进棉花补偿性生长, 减少产量损失; 对于重度损伤棉田, 虽然本试验2个处理的棉田减产幅度皆低于40%, 考虑到雹灾造成的损伤除了物理损伤外, 还会产生冻(冷)害等逆境, 实际减产幅度会大于模拟损伤下的减产幅度, 因此在严重损伤情况下可以考虑改种其他短季作物。
4 结论
棉花蕾期损伤主茎顶心或叶片均会推迟棉花生长发育进程, 但棉花无限生长习性对后期的生物量积累以及经济产量形成产生较强的自我补偿。棉花蕾期损伤主茎顶心或所有叶片推迟了光合系统建成以及净光合速率高峰值的出现, 导致光合产物优先供应营养生长, 减少向棉铃的转运, 最终生物产量基本不会减少, 但棉柴比降低、成熟期推后, 从而造成减产。在轻度和中度损伤后(主茎顶心完好仅部分叶片损伤时), 棉花能够充分发挥自身的超强补偿能力, 做到对营养器官与生殖器官的协调补偿, 减产20%以下, 其中轻度损伤减产5%以内, 轻度和中度损伤情况下应加强水肥管理促进棉花补偿性生长, 减少产量损失; 重度损伤后(全部叶片砸掉), 可考虑改种其他短季作物。参考文献 原文顺序
文献年度倒序
文中引用次数倒序
被引期刊影响因子
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DOI:10.1016/j.fcr.2015.06.008URL [本文引用: 1]
Highlights 61 Cotton yield was also stable across a range of plant densities by manipulating the number of bolls and boll weight under intensive management. 61 Such yield stability was achieved by manipulating dry matter accumulation and partitioning. 61 Early leaf senescence as a result of large boll load was a attribute to lower lint yield at extremely low plant density. Abstract Cotton (Gossypium hirsutum L.) yield under extensive field management across a certain range of plant population densities can be stabilized by manipulating the number of bolls and boll weight, but little is known of similar yield stability under intensive management and how the yield stability is achieved by dry matter accumulation and partitioning under various plant densities. A field experiment was conducted to study the effects of plant density (1.5, 3.3, 5.1, 6.9, 8.7 and 10.5 plants m612) on dry matter accumulation and partitioning in relation to cotton yield. The seedcotton and lint yields at 1.5 plants m612 were significantly lower than those at other plant densities, but there was little difference in either seedcotton or lint yield among plant densities ranging from 3.3 to 10.5 plants m612. Plant biomass increased gradually with increasing plant density. The ratio of dry weight of fruiting forms to plant biomass (DWFF/PB) at 135 days after sowing (DAS) at 1.5 plants m612 exceeded those under 5.1 plants m612 by 12.3%, 6.9 plants m612 by 12.7%, 8.7 plants m612 by 20.5% and 10.5 plants m612 by 21.8%. Also, the harvest index at 1.5 plants m612 exceeded those at 5.1, 6.9, 8.7 and 10.5 plants m612 densities by 16.2, 16.2, 34.3, 38.7%, respectively. Seedcotton yield was positively correlated with total biomass at extremely low plant density (1.5 plants m612), but was better correlated with DWFF/PB at higher densities (5.1–10.5 plants m612). The boll weight of the last harvest was 6.0–6.3% lower than those of the first two harvests at 1.5 plants m612. Leaf senescence as indicated by reduced Pn and leaf area index (LAI) in later season occurred earlier at 1.5 plants m612 than other plant densities. It was concluded that cotton yield is relatively stable across a wide range of plant densities even under intensive field management. The stability was achieved mainly through manipulation of dry matter accumulation and partitioning. The reduced boll weight of the last harvest was mainly due to earlier leaf senescence at 1.5 plants m612, which might explain the lower cotton productivity per unit ground area at such a low plant density.
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DOI:10.1007/s100870050015URL [本文引用: 1]
Abstract tion, resulting in greater fruit production per plant. Boll size was inversely related to population density. Mean net assimilation rate is relatively stable across a wide range of population from first flower to peak bloom also was related inversely to popula- densities. None of the published literature, however, tion density. The mainstem node of peak boll set increased with attempts to determine which components of final lint population density. Fruit production on a ground area basis was yield impart this yield stability across population densi- greater in the first sympodial position as population density increased, ties. Therefore, the objectives of this investigation were while fruit production on a ground area basis in third positions and to determine (i) how yield stability across population monopodial branches was greater as population density decreased. densities is achieved and (ii) how plant population influ- Accumulative seedcotton from sympodial branches also increased ences yield distribution in cotton under growing condi- with population density. Total fruit number and seedcotton yield per tions with high yield potential. area were not influenced by population density in these studies. Yield stability across population densities was achieved through manipula- tion of boll occurrence and weight.
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DOI:10.1016/j.fcr.2005.12.008URL [本文引用: 1]
Cotton is usually managed with a normal planting production system (NPPS) that involves planting in mid-April at a moderate plant density (4.5 plants/m 2) in the Yellow River Valley of China, but drought or cold stress in spring often delays cotton planting, and results in reduced yield and maturity at this plant density. Two experiments were conducted for 4 consecutive years, to test if yield and fiber quality can be maintained or improved by increased plant density for relatively late-planted cotton. Results in the first experiment in 2001 and 2002 showed that average lint yields were not significantly affected by plant density (3.0, 4.5, 6.0 or 7.5 plants/m 2) or by planting date (mid-April or early May), but significant interactions between planting date and plant density on lint yield were detected in both years. Normal planted cotton at a plant density of 3.0-4.5 plants/m 2, and late-planted cotton at 7.5 plants/m 2 produced higher lint yield than other planting date and density combinations. Experiment 2 compared NPPS with a late planting production system (LPPS) which involves planting in early May at 7.5 plants/m 2 over 2 years. The NPPS and LPPS had similar lint yields in both years. Cotton plants in both systems produced approximately 75% of total lint in the first two harvests, indicating no significantly delayed earliness in LPPS relative to NPPS. Fiber from late-season bolls exhibited reduced strength and micronaire in both systems, but there were no significant differences in fiber properties for early- and mid-season fiber between the two systems. In terms of green leaf area index and leaf chlorophyll content, leaf senescence or premature senescence of cotton plants was considerably alleviated by either altered source to sink balance or the uptake of K in LPPS compared to NPPS. It was concluded that the LPPS, a relatively late-planted cotton production system with increased plant density under intensive field management, might be a potential alternative for growing cotton.
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DOI:10.1016/j.fcr.2014.05.010URL [本文引用: 1]
Highlights 61 Both intensive and extensive pruning increased the cotton yield and output value relative to non-pruning. 61 Labor input under extensive pruning was reduced relative to that under intensive pruning. 61 Extensive pruning increased the net revenue due to increase yield and reduced labor input. 61 Extensive plant pruning is a promising alternative for cotton production. Abstract Intensive plant pruning involving removal of vegetative branches, topping, and continuously excising old leaves, growth tips of fruiting branches, excessive buds and empty fruit branches, has been widely adopted in the field management of cotton (Gossypium hirsutum L.) in China, but this practice is facing a serious of challenges because it is labor-intensive and time-consuming. In the present study, an extensive (simplified) pruning system was designed by concurrent removal of vegetative branches and the main-stem leaves below the first fruiting branch at squaring, topping by mid-July when there are 10–12 fruiting branches per plant, and omitting other pruning measures. The objective was to determine if the extensive pruning is better than intensive pruning and non-pruning (plant topping only) in yield and economic benefits. To achieve this goal, two field experiments were conducted at one site from 2011 to 2012 and at five sites in 2013 in the Yellow River delta of China. A split-plot design was used in both experiments with the main plots assigned to cotton cultivars and the subplots assigned to plant pruning (non-pruning, intensive pruning and extensive pruning). The effects of plant pruning, cultivar and their interactions on seed cotton yield were evaluated in both experiments, and on plant growth, harvest index, earliness, yield components and labor input in the first experiment. Both the intensive and extensive plant pruning were beneficial to plant height, harvest index, boll weight and seed cotton yield regardless of cotton cultivar. The extensive pruning was comparable to the intensive pruning system in cotton yield in the first experiment, but produced 4.3% and 4.8% more seed cotton than non-pruning in 2011 and 2012. Greater increases in cotton yield under extensive pruning were obtained in the multi-site experiment in 2013, with an average seed cotton yield increase of 7.7% compared with non-pruning. Both intensive and extensive pruning consumed more labor days than non-pruning, but the labor input under extensive pruning was 76–81% less than that under intensive pruning. Compared with non-pruning, extensive pruning increased the net revenue by 7.9% as a result of improved cotton yield, but intensive pruning decreased net revenue by 3.5% due to increased labor input. The overall results showed that extensive plant pruning is more simplified and beneficial than the traditional intensive pruning and should be a promising alternative in the Yellow River valley of China and other regions with similar ecological conditions.
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DOI:10.1007/s10725-009-9392-xURL [本文引用: 2]
Numerous studies have shown that early-fruit removal enhances vegetative growth and development of cotton ( Gossypium hirsutum L.). However, few studies have examined changes in leaf senescence and endogenous hormones due to fruit removal. The objective of this study was to determine the correlation between some endogenous phytohormones, particularly the cytokinins and abscisic acid (ABA), and leaf senescence following fruit removal. Cotton was grown in pots and in the field during 2005 and 2006. Two early-fruiting branches were excised from plants at squaring to form the fruit removal treatment while the non-excised plants served as control. Plant biomass, seed cotton yield, cytokinins and ABA levels in main-stem leaves and xylem sap as well as main-stem leaf photosynthetic rate (Pn) and chlorophyll (Chl) concentration were determined after removal or at harvest. Fruit removals increased the leaf area, root and shoot dry weight and plant biomass at 3502days after removal (DAR), whether in potted or field-grown cotton; under field conditions, it also improved plant biomass and seed cotton yield at harvest. The Pn and Chl concentration in excised plants were significantly higher than in control plants from 5 to 35 DAR, suggesting that fruit removal considerably delayed leaf senescence. Fruit-excised plants contained more trans -zeatin and its riboside (t-Z02+02t-ZR), dihydrozeatin and its riboside (DHZ02+02DHZR), and isopentenyladenine and its riboside (iP02+02iPA) but less ABA in both main-stem leaves and xylem sap than control plants from 5 to 35 DAR. These results suggest that removal of early fruiting branches delays main-stem leaf senescence, which can be attributed to increased cytokinin and/or reduced ABA. Cytokinin and ABA are involved in leaf senescence following early fruit removal.
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DOI:10.1016/j.fcr.2010.06.019URL [本文引用: 1]
As the most important cultural practices for cotton production, the single effects of plant density and [nitrogen (N) and potassium (K)] fertilization on yield and yield components are well documented but their combined effects on Bt cotton are poorly understood. Using a split-plit plot design with four replications, we conducted a two-year field experiment in two fields, one with lower fertility and the other with higher fertility, in the Yellow River Valley of China. The aim was to evaluate both the individual and combined effects of plant density and nitrogen and potassium fertilization on yield, yield components and uptake of major nutrients. The main plots were assigned to plant density (4.5 and 7.5 plants/m 2), while nitrogen (0 and 240 kg N/ha) and potassium fertilization (0 and 150 kg K/ha) were assigned to the sub- and sub-ubplots. Lint yield was improved with high plant density (7.5 plants/m 2) in the lower fertility field, particularly without N and K application, but not in the higher fertility field. Nitrogen or K application also increased lint yield, and a combination of high plant density, N and K application further improved lint yield in the lower fertility field, while only K application increased lint yield in the higher fertility field. Lint percentage was not affected by any of the variables studied. Thus, the yield increase due to plant density, fertilization or their combinations was attributed to increases in boll number or boll weight. The ratio of seed cotton to stalk (RSS) was linearly correlated with harvest index, and thus can be a simple indicator of dry matter allocation to reproductive structures. Increased yield due to plant density and fertilization was mainly attributed to the enhanced biological yield in the lower fertility field, while the yield increase due to K fertilization was mainly due to increased RSS in the higher fertility field. The plants used approximately equal N and P to produce 100 kg lint in both fields, but the uptake of K to produce 100 kg lint in the higher fertility field was about 21% more than that in the lower fertility field. Ratios of N:P:K were 1:0.159:0.604 in the lower fertility field and 1:0.159:0.734 in higher fertility field. This study suggests that K fertilization was extremely important for maintaining high yield, although luxury consumption occurred in the higher fertility field; N was applied more than required in the highly fertile field, and increased plant density would be beneficial to cotton yield in the lower fertility field.
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DOI:10.1016/j.fcr.2011.10.005URL [本文引用: 1]
Plant density and nitrogen fertilization are two important practices for field-grown cotton ( Gossypium hirsutum L.). The objective of this study was to investigate the effects of plant density and N fertilization rate, especially their interactions, on yield, yield components, late-season leaf senescence and Cry1Ac expression in Bt ( Bacillus thuringiensis) cotton under salinity conditions. To achieve this goal, we conducted a three-year experiment with a high-yielding Bt cotton cultivar (SCRC 28) in a moderately saline (ECe = 11 dS/m) field, using a split-plot design in the Yellow River Delta of China. The main plots were assigned to low, medium and high plant densities (3.0, 5.25 and 7.5 plants/m 2), while low, moderate and high nitrogen rates (120, 225 and 300 kg N/ha) were assigned to the subplots. Biological yield, lint yield, yield components, harvest index, boll load, Cry1Ac expression and leaf senescence were significantly affected by plant density and N rate. Lint yield was also affected by plant density N rate interaction. Increased plant density or N rate enhanced biological yield, but reduced harvest index. Considerably high lint yield (1604 kg/ha) was achieved only with a high dose of N fertilizer under low plant density, but comparable yields (1693 and 1643 kg/ha) were achieved with moderate and low N rate under medium and high plant density. Increased plant density and N rate reduced boll load, which had highly significant negative correlation with late-season leaf photosynthesis ( r = 0.928) and significant correlation with Cry1Ac protein concentration ( r = 0.8131). Leaf senescence was delayed by increasing plant density and N rate mainly due to reduced boll load and a combination of reduced boll load and nutritional effect. Medium plant density with moderate N rate or high plant density with low N rate would enhance cotton yield and moderate Cry1Ac expression at reduced cost in the Yellow River Delta of China and other areas with similar ecologies.
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DOI:10.1016/j.fcr.2016.10.006URL [本文引用: 1]
Relay intercropping of garlic with full-season cotton is currently one of the dominant cropping systems in China, but the net benefit is decreasing because the system is labor-intensive. Direct planting of short-season cotton after garlic harvest may increase net revenue through reducing labor and material input. Three field experiments were consecutively conducted in Jinxiang County of China, to determine the effects of plant density and soil fertility on yield, yield components, boll load and leaf senescence in the 1st and 2nd experiments. In the third experiment, we compared the economic benefits of the two cropping systems. Data from the 1st experiment showed that plant density affected yield and yield components, with the optimum plant density being 3.0plantsm鈭2for full-season cotton and 9.0plantsm鈭2for short-season cotton. In the 2nd experiment, the seedcotton yield of full-season cotton was 9.1% higher under high than medium soil fertility, but there was no yield difference between the two soil fertility levels for short-season cotton. Full-season cotton exhibited larger boll load, earlier leaf senescence and lower boll weight under medium than high fertility. Results of the third experiment showed that seedcotton yield or output value of short-season cotton was 14.5% lower than that of full-season cotton, but the gross return for short-season cotton was 69.2% higher than that for full-season cotton because the short-season cotton required 27.3% less labor and material inputs. The overall results showed that late planted short-season cotton after garlic harvest can be a promising alternative for enhancing the benefits of garlic-cotton production in China.
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DOI:10.1016/j.fcr.2015.05.001URL [本文引用: 1]
In the Yangtze and Yellow River Valleys of China, cotton usually suffers from waterlogging stress at peak flowering. The effects of waterlogging stress on cotton growth and yield are well documented, but little is known of its effects on the biomass allocation to reproductive parts and what determines waterlogging tolerance at physiological and molecular levels. Cotton was grown in a rain-shelter and subjected to a 10 day-waterlogging period to monitor plant growth and yield as well as physiology and expression of genes responsive for waterlogging tolerance. Plant growth and development as indicated by leaf area, plant biomass, biological yield and lint yield were significantly reduced by waterlogging stress. Averaged across the three years of study, the reductions were 26.3, 15.5, 19.8 and 26.1%, respectively. Boll weight and the number of bolls were also significantly reduced by waterlogging stress. The reduced lint yield was ascribed to the decreased boll weight and the number of bolls, as well as reduced plant dry matter accumulation and harvest index. Waterlogging reduced plant photosynthetic (Pn) rate by 16.9% and NO concentration by 17.5% but increased malondialdehyde (MDA) accumulation by 22.2%. The reduced photosynthetic performance was likely due to cell membrane damage resulting from H2O2 accumulation under hypoxic conditions. Waterlogging stress significantly regulated the expression of a set of genes associated with leaf photosynthesis, ROS scavenging, anaerobic metabolism or cell growth like LHCB, CSD, ACS6, ADH, PDC, ERFs, XTHs and EXPAs, which was the likely mechanism of cotton adaptability to waterlogging stress.
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DOI:10.1016/j.fcr.2016.05.006URL [本文引用: 1]
Cotton may suffer from waterlogging from seedling to boll-setting stage, but little is known of how it responds to temporal waterlogging. In this study, cotton was grown in a rain-shelter and subjected to 0 (control)-, 10-, 15- and 20-d waterlogging at squaring (WLS), flowering (WLF) and boll-setting (WLB) stages. The effects of timing (growth stage) and duration of waterlogging on the growth, yield and yield components as well as some physiological and molecular features of cotton were examined. The lint yield was significantly affected by timing and duration of waterlogging as well as their interaction. On average, the 10-, 15-, and 20-d waterlogging reduced lint yield by 53, 59 and 63% at squaring; 27, 37 and 55% at flowering, and 13, 15 and 24% at boll-setting. The more pronounced yield reduction under WLS than later waterlogging (under WLF and WLB) was attributed to greater reductions in biological yield, harvest index, and the resulting boll density and boll weight. Variations in yield loss due to temporal waterlogging was associated with some physiological and molecular changes: a) the chlorophyll synthesis associated gene (GhLHCB) in the main-stem leaves was down-regulated under WLS to a larger extent, leading to lower leaf photosynthesis than that under WLF or WLB; b) cotton alcohol dehydrogenase (GhADH) and pyruvate decarboxylase (PDC) genes were better up-regulated, resulting to greater activity of lactate dehydrogenase (LDH), alcohol dehydrogenase (ADH) and PDC plus lower activity of SOD, POD and CAT and higher accumulation of malondialdehyde (MDA) and H2O2under WLS than under WLF and WLB; c) more pronounced reductions in GA and IAA content were observed under WLS than WLF and WLB. Higher sensitivity to earlier waterlogging than later waterlogging in cotton was attributed to the greater reductions in biological yield and harvest index resulting from differences in physiological and molecular adjustments of the plants.
DOI:10.1016/S0261-2194(97)00110-5URL [本文引用: 3]
The objective of this study was to assess the ability of cotton (Gossypium hirsutum L.) crops to recover after early-season damage by thrips (Thysanoptera). Such information may help clarify the actual need to control thrips. Ten experiments, resulting from the combination of two to four sites per season and three seasons, were carried out in commercial crops in the irrigation area of northwest New South Wales, Australia. Two treatments were compared: unprotected crops and crops protected with aldicarb(2-methyl-2-(methylthio)propanal O-[(methylamino)carbonyl]oxime) at sowing. Early season thrips communities were dominated by Thrips tabaci Lindeman, which accounted for 52 to 100% of the total phytophagous thrips present in the crops. Insecticide treatment consistently reduced the number of larval thrips compared with the unprotected crops. Number of larval thrips per plant ranged from 0 to 24. Thrips reduced crop leaf area in six experiments, dry matter production in four experiments, and yield in two experiments. Maximum differences in leaf area and dry weight between treatments were found about 40 d after sowing. In all cases, crops damaged by thrips recovered well and reached leaf areas and dry weights similar to protected crops after about 60 to 80 d after sowing. On average, protected crops reached maturity 3 d earlier than crops damaged by thrips, but differences were not statistically significant. Despite large reductions in early growth, yield reductions due to thrips were found in only two experiments. The magnitude of the reduction in yield in those experiments (11%) contrasts with the magnitude of the reduction in growth (about 40%) and highlights the ability of the cotton crop to recover after early season damage by thrips.
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DOI:10.1093/jee/85.4.1402URL [本文引用: 1]
The effect of early-season cotton, L., square loss and insect control (primarily thrips, (Pergande)), on the ability of cotton plants to replace lost fruit as well as maintain lint quality was examined in several field trials of differing experimental design in Arizona during 1986-1987. All trials indicated some .degree of compensation for damage to fruiting structures and yield depending upon the timing and plant growth stage. Significant differences in yield were detected only in plots that had squares removed 4 wk after initiation of square production. Most measures of cotton quality were similar among treatments. No differences in fiber strength, elongation, or any color or trash index were calculated for any test. Only a few significant differences between treatments were detected in length, micronaire, or uniformity. However, differences among treatments in all tests were small and all values within a test were still within the same relative range, either "average" or just below "average" range. The treatment with squares removed at 4 wk after square initiation had shorter fiber lengths than those with squares removed early or no removals. 'Deltapine 90' cotton treated with aldicarb at pinhead square had higher micronaire than aldicarb-treated 'Deltapine 77', but there were no differences between treated and untreated plots. Treated 'Deltapine 90' had higher uniformity than untreated 'Deltapine 90', but there were no differences between cultivars or between treated and untreated 'Deltapine 77'. Cotton from plots treated with phorate at planting had higher uniformity ratios than cotton from either aldicarb-treated or control plots. Comparisons of the results of this study are made with those of other regions. Possible factors producing different results are discussed.
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DOI:10.2135/cropsci2001.1800URL [本文引用: 3]
ABSTRACT sions are based on several factors, including insect densi- ties, cultivar/technology utilization, weather, equipment, A better understanding of cotton (Gossypium hirsutum L.) com- and farm size (Mi et al., 1998). Economic thresholds, pensatory growth after loss of early-season floral buds requires an assessment of the actual patterns of spatial yield distribution in dam- however, rarely consider plant compensation for loss of aged and undamaged plants. This study was conducted to determine early-season floral buds as part of the model. Inclusion if spatial yield distribution or yield components are altered in cotton of plant compensation in economic injury levels would in response to removal of early-season floral buds. Beginning with the raise treatment thresholds, thereby reducing insecticide second week of squaring, floral buds were removed by hand for one, applications and the costs, contamination, and resis- two, or three consecutive weeks. At 90 d after planting, plant height, tance development related to them. Prior to inclusion leaf area index, main stem node number, fruit present, total fruiting in an economic injury level, however, the ability of cot- positions, and dry weights were measured. The contribution to total ton to compensate for loss of early-season floral buds yield from each fruiting position was determined at crop maturity. must be fully documented. Results from this study show the lowest level of floral bud removal Many studies have investigated the ability of cotton resulted in no differences in spatial yield distribution. As the intensity of early-season floral bud removal increased, however, the probability to compensate for loss of fruiting forms with results that of harvesting a mature boll decreased in the lower canopy but in- have ranged from small increases to large decreases in creased in the upper canopy. Removal of floral buds resulted in fewer final lint yield (Sadras, 1995). In a review of the litera- first sympodial position fruit but more third sympodial position fruit ture, Sadras (1995) indicated a better understanding of at harvest. Thus, early-season removal of floral buds resulted in addi- compensatory growth after loss of floral buds requires tional seed cotton production on more apical and distal fruiting posi- characterization of the actual patterns of spatial yield tions. These modifications in spatial yield distribution adequately re- distribution in damaged and undamaged plants. Until placed those floral buds removed early in the season because total seed now, no study has been conducted to determine if spatial cotton yield was not different among the treatments at crop maturity. yield distribution in cotton is altered by loss of early-sea- son floral buds. Spatial distribution analyses of final lint yield will more fully determine if and how cotton plants
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DOI:10.2134/agronj1992.00021962008400020017xURL [本文引用: 2]
Cotton (Gossypium hirsutum L.) has a capacity to partially compensate for the loss of floral buds (squares). A 2-yr (1989 and 1990) field study was conducted to determine how growth, yield, and fiber quality traits of different genotypes were affected by early season square removal. Early developing squares were removed by hand, or were induced to abscise by ethephon [(2-chloroethyl)phosphonic acid] application. Genotypes used were 'DPL 50', a normal leaf type, and three leaf type isolines of 'MD 65-11' (normal, okra, and super okra). Compared to the check, the ethephon application decreased plant height by as much as 11% early after application, but the treated plants ultimately exceeded the check by 5% in height, in 1990. The seasonal maximum vegetative dry weight and leaf area index (LAI) did not differ between treatments either year, though the ethephon treatment did increase mainstem node number to 26, compared to 24 nodes for the check. Lint yields did not differ between treatments in 1989, but the ethephon treatment yielded 7% less than the check in 1990. Ethephon application reduced boll size 7% each year, compared to the check. Fiber quality traits were not affected by treatments in 1989, but in 1990 micronaire, maturity, and cell wall thickness were decreased by 6% on fiber from the ethephon plots as compared to the check. This study demonstrated that cotton has potential to compensate for early square loss but did not suggest that early square removal consistently leads to improved yields or fiber quality.
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DOI:10.1603/0022-0493-94.2.388URLPMID:11332830 [本文引用: 3]
In 1996 and 1997, various intensities of prebloom square removal were applied to three cultivars of grown in Mississippi. With the exception of one cultivar in 1997, all cultivars were (Bt)-transgenic . At harvest, the number of and seed weight was recorded for all in each square removal treatment. All cultivars responded similarly to square loss. A yield increase (overcompensation) was observed in the treatment where all squares were removed from the plant one week after squaring began. Only the treatment where all squares were removed before bloom significantly reduced yield and caused a large (>7 d) delay in crop maturation. Otherwise, moderate levels of square removal (approximately 20-50% of prebloom squares) had little impact on overall lint production. However, the patterns of production on the were significantly influenced by the square removal treatments. The removal of relatively more or larger squares increased seed production in late-season fruiting cohorts and on 'vegetative' branches. Compensation for square loss occurred by increasing the relative number and weight of produced subsequent to early-season square removal. Typically, early-season square loss increased the value of later-season fruiting cohorts, especially the midseason cohorts and on vegetative branches. The implications of prebloom square loss, including the compensatory ability of the plant, on insect management are discussed.
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DOI:10.1016/0378-4290(82)90007-7URL [本文引用: 4]
Short fiber cotton ( Gossypium hirsutum L.) was grown at 10 plants per m-row in 96-cm rows on high fertility soils with adequate irrigation. Small squares (floral buds), large squares or small bolls were removed from the cotton crop over various periods, and the subsequent crop response in terms of flowering, boll opening and seed cotton accumulation was followed. In general, removing larger fruiting bodies caused a greater reduction in open bolls than removing smaller fruiting bodies, where the timing of the treatments was comparable. For small square removal, earlier removal caused a greater reduction in open bolls than did later removal. However, the earlier treatments also began to compensate earlier for the effects of damage, and so did not in general have fewer open bolls at the final harvest date than the later treatments. A number of different mechanisms first reduced, and then compensated for, the effects of fruiting body removal on flowering, boll opening and yield. Natural shedding of squares and bolls appeared to be important in reducing the effects of fruiting body removal. The crop compensated for removal with an increased rate of flowering late in the season, increased percentage boll set, and increased boll weight. Not all treatments compensated in all these ways. Nevertheless, no treatment significantly reduced final yield.
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DOI:10.1080/09064710802322147URL [本文引用: 1]
A two-year field experiment was conducted to determine the effects of removal of early-fruiting branches (REFB) on yield, quality, and endotoxin expression in transgenic Bt (Bacillus thuringiensis) cotton (Gossypium hirsutum L.). Two early-fruiting branches of field-grown cotton plants were removed and retained at squaring to form the REFB and the control treatments, respectively. Lint yield, yield components, fibre quality, and Cry1Ac protein concentration in the first fully expanded young leaves on the main stem were measured. Results show that lint yields were increased by 5.1 and 5.5% with REFB compared with control in 2004 and 2005, respectively. There was no difference in fibre quality in the first two harvests between REFB and control, but fibre strength and micronarie in the third harvest were improved with REFB. Levels of total N, soluble protein, and Cry1Ac protein as well as glutamic-pyruvic transaminase (GPT) activity in leaves were higher in REFB than in the control. Laboratory bioassay showed significant enhancement of the control efficacy by REFB in terms of Helicoverpa armigera (Hbner) neonate mortality for both years. It is suggested that REFB might be a potential practice for enhancing transgenic Bt cotton production.
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DOI:10.1017/s0007485308006500URLPMID:19203400 [本文引用: 1]
Understanding the compensatory responses of crops to pest damage is important in developing pest thresholds. Compensation for pest damage in crops can occur at the plant level, where the architecture, growth dynamics and allocation patterns of damaged plants are altered, allowing them to recover or, at the crop level, where differential damage between plants may alter plant-to-plant interactions. We investigated growth and yield of cotton (Gossypium hirsutum L.) following non-uniform manual defoliation of seedlings. This partially replicates real pest damage and is valuable in understanding crop-level responses to damage because it can be inflicted precisely. Damage distributions included damaging 0, 25, 50, 75 or 100% of the plants. Damage intensity for the damaged plants was varied by removing 100 or 75% of each true leaf when plants had two, four and six true leaves. At the crop level, yield loss increased as the proportion of plants damaged and intensity of damage per damaged plant increased. Neighbour interactions occurred; undamaged plants with damaged neighbours grew larger and yielded better than undamaged plants with undamaged neighbours, while the converse applied for damaged plants with undamaged neighbours. Neighbour interactions were influenced by the intensity of damage and were stronger when 100% of the leaf area was removed than when 75% was removed. At the crop level, when compared with yield estimates based on yield of plants from uniformly damaged or undamaged plots, these interactions resulted in higher yield than expected (+8%). This suggests that damage distribution may have to be considered in studies where artificial or real pest damage is inflicted uniformly on plants.
