宋光雷, 睢宁, 余超然, 张凡, 孟亚利, 陈兵林, 赵文青, 王友华^*
南京农业大学农学院 / 农业部南方作物生理生态重点开放实验室, 江苏南京 210095
^*通讯作者(Corresponding author): 王友华, E-mail: w_youhua126@126.com, Tel: 025-84396129 第一作者联系方式: E-mail: 2012101054@njau.edu.cn
收稿日期:2015-03-16 接受日期:2015-06-01网络出版日期:2015-06-29基金:本研究由国家自然科学基金项目(31371583)资助

摘要为研究棉田化学钾肥的秸秆替代施入对棉仁含油量的影响及其生理生化基础, 2012—2013年于江苏省农业科学院试验站进行麦棉两熟周年秸秆还田定位试验, 在棉花季设置小麦秸秆不还田(0, W₀)、半量还田(4500 kg hm^-2, W₁)和全量还田(9000 kg hm^-2, W₂), 在小麦季设置棉花秸秆不还田(0, C₀)、半量还田(3750 kg hm^-2, C₁)和全量还田(7500 kg hm^-2, C₂), 两种作物秸秆不同还田量组合后共9个秸秆还田处理, 另根据秸秆折合钾肥量, 于2012年棉花季开始增设2个钾肥用量处理, 即150 kg K₂O hm^-2和300 kg K₂O hm^-2(K₁和K₂)。研究显示, 在适宜氮肥(300 kg N hm^-2)、磷肥(150 kg P₂O₅ hm^-2)水平下, 随着逐年秸秆还田与施钾, 土壤速效氮、有效磷年际间差异均不显著, 但土壤速效钾含量年际间存在显著差异; 花后17 d、24 d是不同处理条件下棉仁含油量差异形成的关键时期; 相较于6-磷酸葡萄糖脱氢酶(G6PDH)、磷酸烯醇式丙酮酸羧化酶(PEPC), 花后17 d、24 d的磷脂酸磷酸酯酶(PPase)的活性对棉仁油分的通径系数更大。结果表明, 短期秸秆还田与单施化学钾肥均主要影响棉田土壤速效钾含量; 从棉仁油分累积角度来看, 秸秆还田可在很大程度上替代化学钾的施入; 花后17 d、24 d棉仁钾含量是影响棉仁含油量的关键因子; 秸秆还田替代化学钾肥条件下, PPase较G6PDH、PEPC对棉仁油分的影响更为关键。

关键词:棉仁; 油分; 秸秆还田; 钾肥
Effects of Straw-Returning Instead of Chemical Potassium Application on Oil Accumulation in cotton seed Embryo in Wheat-Cotton Rotation System
SONG Guang-Lei, SUI Ning, YU Chao-Ran, ZHANG Fan, MENG Ya-Li, CHEN Bing-Lin, ZHAO Wen-Qing, WANG You-Hua^*
Nanjing Agricultural University / Key Laboratory of Crop Physiology & Ecology in Southern China, Ministry of Agriculture, Nanjing 210095, China

AbstractA field experiment was carried out to study the influence of straw returning to field (taking the place of chemical potassium fertilization) on cotton seed lipid content and its physiological mechanism in 2012—2013 in the research station of Jiangsu Academy of Agricultural Sciences in Nanjing. Application rates of wheat straw were designed as 0, 4500, and 9000 kg ha^-1(W₀, W₁, and W₂) in cotton season. Similarly, application rates of cotton straw were designed as 0, 3750, and 7500 kg ha^-1(C₀, C₁, and C₂) in wheat reason. There were nine straw-returning treatments with combinations of two kinds of crop straw at returning different amounts. Additionally, according to the straw potassium content, K fertilizer rates were newly designed as 150 and 300 kg K₂O ha^-1 (K₁ and K₂) in cotton season in 2012. The results showed that under the condition of optimized nitrogen (300 kg N ha^-1) and phosphate (150 kg P₂O₅ ha^-1) fertilization levels, with straw returning and the chemical potassium fertilizer application year by year, the differences of soil available nitrogen and phosphorus between years were not significant, while those of soil K content were significantly different. The 17th day and 24th day after anthesis (DAA) were the key period for the difference of cotton seed oil formation. Under the chemical potassium fertilization and the straw returning condition, the phosphatidic acid phosphatase (PPase) contributed more to cotton seed oil accumulation than glucose 6-phosphate dehydrogenase (G6PDH) and phosphoenolpyruvate carboxylase (PEPC) in response to soil potassium nutrition. The result indicated that, the soil available K content was the major nutrition factor that was significantly affected by the two-year straw returning and the chemical potassium fertilizer application. Straw returning to field can take the place of chemical potassium application to a high extent. The amount of straw returning will affect potassium content of the soil. Low potassium stress will accelerate the aging of cotton plant, and might be a straight reason that caused the difference of oil content. The potassium content in the cotton seed at 17th day, 24th day after anthesis is a key nutrition factor that may lead to the difference of cotton seed oil content. The phosphatidic acid phosphatase (PPase) plays a more important role than glucose 6-phosphate dehydrogenase (G6PDH), phosphoenolpyruvate carboxylase (PEPC) in cotton seed oil accumulation in response to soil potassium nutrition.

Keyword:cotton seed embryo; Oil content; Returning straw; Potassium fertilizer
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钾是植物正常生长发育所必需的大量营养元素之一^[1], 在农业生产中至关重要^[2]。棉花属于喜钾作物, 棉田土壤钾素不足时, 易出现缺钾性早衰, 导致棉花产量和品质下降^{[3, 4]}。我国生产的钾肥仅能满足国内钾肥需求量的30%左右, 农田缺钾面积逐年扩大, 钾素亏缺已成为农业生产持续发展的限制因素之一^[5]。而我国秸秆资源丰富^[6], 秸秆还田具有替代化学钾肥的作用^[7], 故实施棉田秸秆还田, 对减少化学钾肥的依赖具有重要的理论和实践意义。
棉籽作为世界重要的植物油来源, 其应用潜力方面的研究逐渐引起人们的关注^{[8, 9]}。相关研究表明, 棉籽含油量因其生长季节、年份及地点变化而不同, 受温度^[10]、肥料^{[11, 12, 13]}等环境因素的影响。研究发现施钾显著提高棉籽油分含量和油分产量, 缺钾则降低其含油量^{[14, 15]}。棉籽内油脂的形成离不开相关代谢酶的参与。同时胞质中高浓度的钾是维持酶活性的关键^{[16, 17]}。基于酶活性高低可作为物质代谢途径强弱指标之一的观点, 有必要开展酶活性变化与脂肪合成途径之间关系的研究工作。然而目前对于秸秆还田替代化学钾肥条件下的棉仁油分累积特征及其相关酶活性变化尚未见研究报道。
本试验拟研究麦(转基因抗虫)棉两熟定位试验中周年秸秆还田替代化学施钾条件下棉仁含油量差异、棉仁油分累积特征、及其相关生理过程的酶活性变化, 以阐明秸秆替钾条件下影响棉仁油分累积的关键时期及其生理基础。
1 材料与方法1.1 试验地概况江苏省南京市(32° 02′ N, 118° 50′ E)江苏省农业科学院试验站土壤质地为黏质土, 偏酸性(pH 5.7), 试验开始前冬季休闲未种植其他作物。2011年供试土壤速效氮、有效磷与速效钾含量分别为24.2 mg kg^-1、15.1 mg kg^-1和154.6 mg kg^-1。
1.2 试验设计麦棉两熟周年秸秆还田定位试验始于2011年4月棉花生长季。长江下游地区实际生产中, 高产条件下小麦籽粒产量6000 kg hm^-2、棉花籽棉产量4500~6000 kg hm^-2时, 可生产的小麦秸秆量约为9000 kg hm^-2、棉花秸秆量约为7500 kg hm^-2。据此, 本试验在棉花季设置小麦秸秆不还田(0, W₀)、半量还田(4500 kg hm^-2, W₁)和全量还田(9000 kg hm^-2, W₂)(图1), 在小麦季设置棉花秸秆不还田(0, C₀)、半量还田(3750 kg hm^-2, C₁)和全量还田(7500 kg hm^-2, C₂), 两种作物秸秆不同还田量组合后共9个秸秆还田处理。全量小麦秸秆钾含量约合150 kg K₂O hm^-2。全量棉花秸秆钾含量约合225 kg K₂O hm^-2。在2012年棉花季开始增设150 kg K₂O hm^-2和300 kg K₂O hm^-2(K₁和K₂) 2个钾肥用量处理, 钾肥仅在棉花生长季施用, 小麦生长季不施。
按照随机区组设计试验处理, 3次重复。小区面积28 m²(7 m× 4 m), 棉花7行区种植, 行距1 m, 株距0.3 m, 种植密度33 000株 hm^-2。小麦条播, 行距15 cm, 播种量为150 kg hm^-2。小麦秸秆覆盖还田, 待棉花初花期结合中耕培土将小麦秸秆翻入约10 cm土层; 棉花秸秆通过机械翻埋入土约10 cm, 然后进行小麦播种。
选用小麦品种宁麦13, 于每年11月5日至10日播种, 施氮磷肥, N、P₂O₅分别为300、150 kg hm^-2。棉花品种选用长江流域棉区主栽转基因抗虫棉品种泗杂3号, 于4月25日营养钵育苗, 麦收后6月5日左右大苗移栽, 施氮量为300 kg hm^-2, 按基肥40%、初花肥40%、盛花肥20%施用; 施磷量为150 kg hm^-2, 棉花移栽时施用; 秸秆还田处理均不施钾肥, 施钾处理选用硫酸钾化肥(50%), 与小麦秸秆同期施入。其他田间管理措施均按高产栽培要求进行。
1.3 基础土壤养分测定2011— 2013年棉花生育期内, 苗期(6月5日)用取土器取0~20 cm土层土壤, 去杂, 过筛, 部分于-20℃冰箱保存待测定速效氮; 部分用于测定全氮、有机质、有效磷、速效钾。
采用凯氏定氮法测全氮^[18]; 采用连续流动分析仪测速效氮^[19]; 采用钼锑抗比色法测有效磷^[19]; 用1.0 mol L^-1乙酸铵溶液提取, 原子吸收分光光度计法测速效钾^[18]。
图1
Fig. 1

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图1 田间试验设计 基础土壤指标测定于移栽期, 取1/2株距20 cm土层土壤, 测定速效氮、有效磷及速效钾含量。秸秆与基肥同期施入。W0: 小麦秸秆不还田; W1: 4500 kg hm-2小麦秸秆还田量; W2: 9000 kg hm-2小麦秸秆还田量; C0: 棉花秸秆不还田; C1: 3750 kg hm-2棉花秸秆还田量; C2: 7500 kg hm-2棉花秸秆还田量; K1: 150 kg K2O hm-2施钾量; K2: 300 kg K2O hm-2施钾量。Fig. 1 Trials design in field Basic available N, P and K at 1/2 spacing and 0-20 cm depth in the soil were determined during the transplanting period. Straw and fertilizer applied at the same period. W0: no application rates of wheat straw; W1: application rates of wheat straw were designed as 4500 kg ha-1; W2: application rates of wheat straw were designed as 9000 kg ha-1; C0: no application rates of cotton straw; C1: application rates of cotton straw were designed as 3750 kg ha-1; C2: application rates of wheat straw were designed as 7500 kg ha-1; K1: K fertilizer rates were designed as 150 kg K2O ha-1; K2: K fertilizer rates were designed as 300 kg K2O ha-1.

1.4 棉仁生理样品收取与测定于棉株第6~第8果枝第1~第2果节开花时, 挂牌标记当日内所开白花。于花后17、24、31、38和45 d, 直至棉铃吐絮, 上午9:00— 10:00时从每小区取生长一致的标记棉铃6~8个, 于低温条件下分离纤维与种子, 部分经液氮速冻后-80℃保存, 用于脂肪代谢相关酶活性测定, 剩余部分分离出棉仁和棉籽壳, 105℃杀青30 min, 50℃烘干, 供棉仁含油量与棉仁钾含量的测定。
采用索氏抽提法测定棉仁油分含量^[20]。参照陈玉萍等^[21]和Wang等^[22]方法测定6-磷酸葡萄糖脱氢酶(G6PDH)活性; 参照西北农林科技大学的方法^[23]测定磷脂酸磷酸酯酶(PPase)活性; 参照Sebei等^[24]方法测定磷酸烯醇式丙酮酸羧化酶(PEPC)活性。
1.5 数据分析采用Microsoft Excel 2003软件分析数据并绘图; 用SPSS17.0软件进行方差分析, 采用LSD法进行处理间平均值差异显著性检验; 用Origin9.0绘图。

2 结果与分析2.1 土壤速效钾、速效氮、有效磷含量施钾和秸秆还田均提高棉田耕层土壤(0~20 cm)速效钾含量。与W₀C₀(K₀)相比, 2012年秸秆还田处理棉田耕层土壤速效钾平均增加5.7%, 施钾处理未增加; 而2013年秸秆还田处理增加28.2%, 施钾处理增加46.9%, 说明随定位试验逐年进行, 秸秆还田具有补偿土壤钾素的能力, 但效果不及化学钾肥的直接施用。
秸秆还田对土壤速效氮、有效磷表现出一定的影响。2012年同一小麦秸秆水平下, 随棉花秸秆还田量的增加, 土壤速效氮含量降低; 至2013年各处理间土壤速效氮含量差异不显著。2012年棉田土壤有效磷含量各处理间差异不显著; 至2013年同一小麦秸秆水平下, 随棉花秸秆还田量的增加, 土壤有效磷含量表现下降趋势。
差异显著性比较发现, 土壤速效氮、有效磷年际间差异均不显著, 但土壤速效钾含量年际间差异显著, 说明随着秸秆还田的逐年进行, 秸秆还田主要显著影响棉田土壤的速效钾含量(图2)。
2.2 棉仁产量、棉仁油分产量及棉仁含油量秸秆还田与施钾显著增加棉仁产量和油分产量(表2)。以2013年为例, 与W₀C₀(K₀)相比, 秸秆还田下平均棉仁产量及油分产量分别为922 kg hm^-2、311 kg hm^-2, 产量增幅为61%、72%; 施化学钾肥下平均棉仁产量及油分产量分别为1280 kg hm^-2、446 kg hm^-2, 产量增幅为123%、146%, 说明秸秆还田能在一定程度上替代化学钾肥施用。结合变异来源分析可知(表1), 麦秆还田处理对棉仁含油量影响显著, 但棉杆还田对其影响不显著, 说明相较于前茬棉杆还田, 当季麦秆还田是影响棉仁含油量主要因素。麦秆还田处理与施钾处理均显著提高了棉仁含油量(表2)。
图2
Fig. 2

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图2 土壤速效氮、有效磷、速效钾含量(2012-2013) * * 表示在0.01水平差异显著; ns: 差异不显著; F1: 2012年处理间差异; F2: 2013年处理间差异; FY: 年际间差异。其他缩写同图1。Fig. 2 The content of available N, P, and K in the soil in 2012 and 2013 * * : significant differences at the 0.01 probability level; ns: not significant; F1: difference between treatments in 2012; F2: difference between treatments in 2013; FY: differences between years. Other abbreviations are the same as those given in Fig. 1.

表1
Table 1
表1(Table 1)

表1 棉仁产量、油分含量及油分产量变异来源分析(2012-2013) Table 1 Variation sources analysis of cotton seed embryo yield, oil content and oil yield in 2012 and 2013 变异来源 Sources of variation 棉仁产量 cotton seed embryo yield ( kg hm-2) 油分含量 Oil content (%) 油分产量 Oil yield (kg hm-2) 年份Y 0.981 66.406* * 0.001 小麦秸秆W 95.739* * 92.612* * 116.692* * 棉花秸秆C 2.078 1.434 2.473 Y× W 6.950* * 3.925* 7.301* * Y× C 1.894 0.250 1.705 W× C 0.468 1.288 0.524 Y× W× C 0.463 1.332 0.498 Y: year; W: wheat straw; C: cotton residue. F-values and significance levels (* * P < 0.01, * P < 0.05) are given.

表1 棉仁产量、油分含量及油分产量变异来源分析(2012-2013) Table 1 Variation sources analysis of cotton seed embryo yield, oil content and oil yield in 2012 and 2013

2.3 棉仁油分累积棉仁油分的累积符合“ S” 型生长曲线(图3), 可用Logistic方程拟合, 发现秸秆还田与施钾均明显影响其累积特征值。麦秆还田与施钾处理下棉仁油分快速累积起始期(DPA₁)和终止时期(DPA₂)较W₀C₀(K₀)推迟、快速累积持续期(T)延长、油分含量理论最大值(OC_max)和实测值(OC_obs)均升高。结合油分累积特征值间的相关性可知(表3), OC_max、OC_obs与DPA₁、DPA₂、T显著正相关, 说明棉仁油分旺盛累积时期是影响棉仁最终含油量的关键因子。
随麦秆还田与施钾逐年进行, 麦秆还田处理下DPA₁和DPA₂较单施化学钾肥提前、T缩短、OC_max、OC_obs均降低(2013年)。棉仁油分快速累积持续期主要集中于花后17~24 d, 且不同处理下该时期累积速率存在显著差异, 因此可确定花后17 d、24 d为不同处理条件下棉仁含油量差异形成的关键时期。
2.4 棉仁钾含量及钾含量动态变化棉仁吐絮期钾含量因受秸秆还田或施钾影响呈上升趋势(图4)。结合相关性分析发现(图5), 棉仁吐絮期钾含量与吐絮期油分含量呈极显著正相关, 表明棉仁钾含量与含油量密切相关, 推测其是影响含油量的关键因子。
表2
Table 2
表2(Table 2)

表2 麦棉两熟周年秸秆还田对棉仁产量、棉仁油分产量及棉仁含油量的影响(2012-2013) Table 2 Effects of straw-returning on cotton seed embryo yield, oil content and oil yield in the wheat-cotton rotation system in 2012 and 2013 处理 Treatment 2012 2013 棉仁产量 Embryo yield ( kg hm-2) 棉仁含油量 Embryo oil content (%) 棉仁油分产量 Embryo oil yield (kg hm-2) 棉仁产量 Embryo yield (kg hm-2) 棉仁含油量 Embryo oil content (%) 棉仁油分产量 Embryo oil yield (kg hm-2) C0W2 1072 a 35.4 a 379 a 1130 a 35.1 a 393 a C0W1 1055 a 34.8 a 367 a 769 b 33.0 b 254 b C0W0 442 b 33.2 b 147 b 573 c 31.7 c 181 c C1W2 1055 a 35.2 a 371 a 1091 a 34.5 a 376 a C1W1 980 a 34.8 a 340 a 891 b 33.3 a 297 b C1W0 485 b 33.2 b 161 b 568 c 31.8 b 181 c C2W2 1017 a 35.7 a 362 a 1177 a 34.8 a 409 a C2W1 1048 a 35.1 a 369 a 1009 b 34.3 a 345 b C2W0 497 b 33.6 b 167 b 738 c 31.0 b 229 c K2 871 a 35.9 a 313 a 1335 a 35.4 a 472 a K1 1018 a 35.6 a 362 a 1224 a 34.3 b 419 a K0 442 b 33.2 b 147 b 573 b 30.6 c 175 b Values followed by a different letter within the same column are significantly different at the 0.05 probability level, respectively. Abbreviations are the same as those given in Fig. 1. 同一列中不同字母表示在0.05水平上差异显著。缩写同图1。

表2 麦棉两熟周年秸秆还田对棉仁产量、棉仁油分产量及棉仁含油量的影响(2012-2013) Table 2 Effects of straw-returning on cotton seed embryo yield, oil content and oil yield in the wheat-cotton rotation system in 2012 and 2013

图3
Fig. 3

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	图3 麦棉两熟周年秸秆还田对棉仁油分累积的影响(2012-2013) 缩写同图1。曲线趋势相似, 故C2W2、C2W1、C2W0、C1W2、C1W1、C1W0未列出。Fig. 3 Effect of straw-returning on cotton seed embryo oil accumulation in the wheat-cotton rotation system in 2012 and 2013 Abbreviations are the same as those given in Fig. 1. C2W2, C2W1, C2W0, C1W2, C1W1, C1W0 are not listed due to the similar curve trend.

表3
Table 3
表3(Table 3)

表3 棉仁油分累积特征值之间的相关性分析(2012-2013) Table 3 Correlation between OCmax, OCobs and DPA1, DPA2, T(OC), and V(OC)max in 2012 and 2013 年份 Year 性状 Trait DPA1 DPA2 T(OC) V(OC)max 2012 OCmax 0.872* * 0.911* * 0.848* * -0.815* * OCobs 0.819* * 0.806* * 0.714* -0.678* 2013 OCmax 0.870* * 0.944* * 0.891* * -0.688* OCobs 0.918* * 0.946* * 0.826* * -0.593 DPA1: oil rapid accumulation starting time; DPA2: oil rapid accumulation termination time; T(OC): duration of oil speedy accumulation; V(OC)max: maximal speed of oil accumulation; OCmax: theoretical maximum of oil content; OCobs: final oil content (measured value); * and * * indicate significant correlation at the 0.05 and 0.01 probability levels, respectively (n=11, R20.05=0.6, R20.01 = 0.7). DPA1: 油分快速累积起始时期; DPA2: 油分快速累积终止时期; T(OC): 油分快速累积持续时期; V(OC)max: 油分最大累积速率; OCmax: 油分含量理论最大值; OCobs: 最终油分含量(实测值); * 和* * 分别表示0.05和0.01水平相关显著(n=11, R20.05=0.6, R20.01=0.7)。

表3 棉仁油分累积特征值之间的相关性分析(2012-2013) Table 3 Correlation between OCmax, OCobs and DPA1, DPA2, T(OC), and V(OC)max in 2012 and 2013

图4
Fig. 4

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图4 麦棉两熟周年秸秆还田对棉仁钾含量的影响(2012-2013) * 与* * : 在0.05与0.01水平差异显著。缩写同图1。曲线趋势相似, 故C2W2、C2W1、C2W0、C1W2、C1W1、C1W0未列出。Fig. 4 Effect of straw-returning on the K content of cotton seed embryo in the wheat-cotton rotation system in 2012 and 2013 * and * * : significant differences at the 0.05 and 0.01 probability levels, respectively. Abbreviations are the same as those given in Fig. 1. C2W2, C2W1, C2W0, C1W2, C1W1, C1W0 are not listed due to the similar curve trend.

棉仁钾含量动态变化表现先增后减, 最后有所回升的趋势。通过上面分析已知, 花后17 d、24 d为不同处理条件下棉仁含油量差异形成的关键时期。对该时期钾含量及其对应时期含油量进行相关性分析发现(图5), 两者呈极显著正相关, 说明该时期的棉仁钾含量是影响棉仁含油量的关键因子。
2.5 脂肪合成相关酶G6PDH、PPase、PEPc受秸秆还田或施钾影响均表现棉仁发育前期活性较高, 后期活性显著降低(图6)。与2012年相比, 2013年各相关酶活性峰值明显提前。
基于17DPA和24DPA是不同处理下含油量差异的关键时期, 棉仁油脂代谢路径及棉仁钾含量和油分含量与脂肪合成相关酶G6PDH(6-磷酸葡萄糖+NADP^{+ G6PDH} 6-磷酸葡萄糖酸内酯+NADPH)、PPase (磷脂酸+H₂O ^PPase 二酰甘油+H₃PO₄)、PEPC(磷酸烯醇式丙酮酸+CO₂+H₂O ^{PEPC, Mg} 草酰乙酸+无机磷酸)活性关系密切, 取17DPA、24DPA棉仁钾含量、G6PDH、PPase、PEPC酶活性及棉仁油分含量作通径分析。结果显示, 花后17 d、24 d的PPase对棉仁含油量的影响最关键。以2013年花后24 d为例, 相较于G6PDH (通径系数0.194、施钾检验值0.271)、PEPC (通径系数0.089、检验值0.091), PPase (通径系数0.549、检验值0.317)的活性对棉仁油分的影响更为关键, 是导致不同处理条件下油分含量差异的关键酶。两年规律一致。
图5
Fig. 5

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	图5 棉仁钾含量与含油量相关性分析(2012-2013) * * : 在0.01水平相关显著(n=11, R20.05=0.3626; R20.01=0.5408)。 DAA: 花后天数; BOS: 吐絮期。Fig. 5 Correlation between average K content of developing cotton embryo and its final oil content in 2012 and 2013 * * : significant correlation at 0.01 probability level (n=11, R20.05=0.3626; R20.01=0.5408). DAA: days after anthesis; BOS: boll opening stage.

3 讨论秸秆钾多数以离子形式存在, 较秸秆中的氮、磷元素释放更快, 短期内可显著提高土壤钾含量。进一步的研究还需考虑到秸秆中除含有大量的钾元素之外, 还含有丰富的氮磷元素, 以及秸秆还田对土壤微量元素、有机质及土壤结构等的影响。前人关于秸秆还田对土壤养分状况影响的研究表明, 长期秸秆还田(多为10年以上的长期定位试验)显著提高土壤氮、磷等养分含量^{[25, 26]}, 但是短期秸秆还田难以显著影响其含量^{[27, 28]}。睢宁等^[29]于江苏省农业科学院试验站的研究结果显示, 短期麦棉复种小麦秸秆还田对棉田土壤有机碳、全氮、有效磷、速效氮影响均不显著, 但显著提高了土壤速效钾含量。本试验仅3年定位, 且在棉花移栽前、花铃期和小麦播种前均翻土耕作, 因此秸秆还田对土壤结构的影响较小。本研究为了避免土壤中氮、磷养分差异对研究结果的影响, 基于长江中下游地区棉田肥料施用情况, 足量施用了氮磷肥, 保证了秸秆钾是影响棉株生长发育的关键因子。
本研究表明, 与麦秆还田处理相比, 麦秆不还田处理(W₀)的棉仁油分快速累积起始期(DPA₁)和终止时期(DPA₂)提前、快速累积持续期(T)缩短、油分含量理论最大值(OC_max)和实测值(OC_obs)均降低; 油分累积相关酶G6PDH、PPase、PEPC活性峰值均表现提前。根据矿质营养失调假说, 作物营养平衡失调, 就会出现生育异常, 有时这种生育异常表现为早衰^[30]。研究表明钾素缺乏极易引起棉花早衰; 杨铁钢等^[31]发现, 在养分限制条件下, 棉株载铃量过大时, 株高、果枝会受到强烈的胁迫, 营养生长受到显著不利影响, 造成根部营养缺乏, 进而引发棉株早衰。转基因抗虫棉具有载铃多的特点, 缺钾条件下更容易引发棉株早衰减产。综上, 在转基因抗虫棉载铃量大, 同时对缺钾敏感的条件下, 本试验中秸秆钾输入量不同引起土壤钾素含量差异而造成的棉株不同程度的早衰, 可能是影响棉仁含油量累积动态特征差异的直接原因。
图6
Fig. 6

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图6 麦棉两熟秸秆还田对棉仁发育过程中G6PDH、PPase、PEPC活性的影响(2012-2013) 缩写同图1。因曲线趋势相似, 故C2W2、C2W1、C2W0、C1W2、C1W1、C1W0未列出。Fig. 6 Effect of consecutive crop residue incorporation on activities of G6PDH, PPase, PEPC during the development of cotton seed embryo in the wheat-cotton rotation system in 2012 and 2013 Abbreviations are the same as those given in Fig. 1. C2W2, C2W1, C2W0, C1W2, C1W1, C1W0 are not listed due to the similar curve trend.

图7
Fig. 7

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	图7 棉仁钾含量、G6PDH、PPase、PEPC及棉仁油分含量间通径分析Fig. 7 Path analysis of cotton seed embryo K content, G6PDH, PPase, PEPC, and oil content

本研究发现, 在秸秆钾替代条件和单独化学钾肥施用条件下, 相较于参与能量供给的G6PDH和碳源竞争的PEPC, 直接参与脂肪合成调控的PPase对钾素更敏感, 对棉仁含油量的影响更为关键。研究表明: PPase的功能是催化磷脂酸形成二酰甘油, 而二酰甘油是三酰甘油合成的直接前体, 由该酶催化形成二酰甘油得以保证三酰甘油的合成速率; 而G6PDH催化6-磷酸葡萄糖生成NADPH, 为脂肪酸的合成提供还原力的关键酶^{[32, 33]}, PEPC是控制油脂和蛋白质生物合成的共同底物— — 磷酸烯醇式丙酮酸的流向的主要酶, 决定蛋白质与脂肪的比例^[34]。因此本研究结果表明在棉籽油脂代谢中, 磷脂酸合成过程比能量供应和碳源分配更易受棉籽内钾素水平的影响。
棉籽油的亚油酸含量达46.7%~58.2%, 是一种优质的食用植物油^[35]。施钾提高油脂品质, 但施钾也明显提高有毒物质— — 棉酚的含量^[36], 不利于棉籽的综合利用。棉仁的油分累积过程与其最终含油量密切相关, 直接影响棉籽油产量, 故本研究主要探讨了秸秆还田替代化学钾肥条件下棉仁油分累积特征的差异, 而未考虑该条件下棉仁油脂品质形成的差异, 这有待进一步研究。
4 结论秸秆还田与施钾均可显著增加棉仁产量和油分产量, 从棉籽油分形成角度看, 秸秆还田可基本替代化学钾肥施用; 花后17 d、24 d为不同钾处理条件下含油量差异形成的关键时期, 该时期的棉仁钾含量是影响棉仁含油量的关键因子; 在生理上, 秸秆还田替代化学钾肥条件下, PPase较G6PDH、PEPC对棉仁油分的影响更为关键。
The authors have declared that no competing interests exist.

作者已声明无竞争性利益关系。


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被引期刊影响因子

[1]	Marschner H, Rimmington G M. Mineral nutrition of higher plants. Plant Cell Environ, 1988, 11: 147-148[本文引用:1]
[2]	Zörb C, Senbayram M, Peiter E. Potassium in agriculture-status and perspectives. J Plant Physiol, 2014, 171: 656-669[本文引用:1]
[3]	董合忠, 唐薇, 李振怀, 张冬梅, 李维江. 棉花缺钾引起的形态和生理异常. 西北植物学报, 2005, 25: 615-624 Dong H Z, Tang W, Li Z H, Zhang D M, Li W J. Morphological and physiological disorders of cotton resulting from potassium deficiency. Acta Bot Boreali-Occident Sin, 2005, 25: 615-624 (in Chinese with English abstract)[本文引用:1]
[4]	Zhang Z Y, Tian X L, Duan L S, Wang B M, He Z P, Li Z H. Differential responses of conventional and Bt-transgenic cotton to potassium deficiency. J Plant Nutr, 2007, 30: 659-670[本文引用:1]
[5]	白由路. 高价格下我国钾肥的应变策略. 中国土壤与肥料, 2009, (3): 1-4 Bai Y L. Response strategy of potassium fertilizer under high price in China. Soil Fert Sci China, 2009, (3): 1-4 (in Chinese with English abstract)[本文引用:1]
[6]	王亚静, 毕于运, 高春雨. 中国秸秆资源可收集利用量及其适宜性评价. 中国农业科学, 2010, 43: 1852-1859 Wang Y J, Bi Y Y, Gao C Y. Collectable amount sand suitability evaluation of straw resource in China. Sci Agric Sin, 2010, 43: 1852-1859 (in Chinese with English abstract)[本文引用:1]
[7]	李继福, 鲁剑巍, 任涛, 丛日环, 李小坤, 周鹂, 杨文兵, 戴志刚. 稻田不同供钾能力条件下秸秆还田替代钾肥效果. 中国农业科学, 2014, 47: 292-302 Li J F, Lu J W, Ren T, Cong R H, Li X H, Zhou L, Yang W B, Dai Z G. Effect of straw incorporation substitute for K-fertilizer under different paddy soil K supply capacities. Sci Agric Sin, 2014, 47: 292-302 (in Chinese with English abstract)[本文引用:1]
[8]	Karaosmanoglu F, Tuter M, Gollu E, Yanmaz S, Altintig E. Fuel properties of cotton seed oil. Energy Sourc, 1999, 21: 821-828. [本文引用:1]
[9]	Meneghetti S M P, Meneghetti M R, Serra T M, Barbosa D C, Wolf C R. Biodiesel production from vegetable oil mixtures: cotton seed, soybean, and castor oils. Energy Fuels, 2007, 21: 3746-3747[本文引用:1]
[10]	Gipson J R, Joham H E. Influence of night temperature on growth and development of cotton (Gossypium hirsutum L. ): IV. Seed quality. Agron J, 1969, 61: 365-367[本文引用:1]
[11]	Anderson O E, Worthington R E. Boron and manganese effects on protein, oil content, and fatty acid composition of cotton seed. Agron J, 1971, 63: 566-569[本文引用:1]
[12]	Leffler H R, Elmore C D, Hesketh J D. Seasonal and fertility-related changes in cotton seed protein quantity and quality. Crop Sci 1977, 17: 953-956[本文引用:1]
[13]	Elmore C D, Spurgeon W I, Thom W Q. Nitrogen fertilization increases N and alters amino acid concentration of cotton seed. Agron J, 1979, 71: 713-716[本文引用:1]
[14]	Sawan Z M, Hafez S A, Basyony A E, Alkassas A E E R. Cotton seed, protein, oil yields and oil properties as influenced by potassium fertilization and foliar application of zinc and phosphorus. World J Agric Sci, 2006, 2: 66-74[本文引用:1]
[15]	Sawan Z M, Hafezb S A, Basyony A E, Alkassas A E E R. Cotton seed: protein, oil yields, and oil properties as influenced by potassium fertilization and foliar application of zinc and phosphorus. Grasas Y Aceites, 2007, 58: 40-48[本文引用:1]
[16]	Leigh R A, Wyn-Jones R G. Cellular compartmentation in plant nutrition: the selective cytoplasm and the promiscuous vacuole. Adv Plant Nutr USA, 1986, 2: 249-279[本文引用:1]
[17]	Suelter C H. Role of potassium in enzyme catalysis. Potass Agric, 1985, 337-350[本文引用:1]
[18]	鲁如坤. 土壤农业化学分析方法. 北京: 中国农业科技出版社, 1999. p 147 Lu R K. Method for agro-chemical analyses of soil. Beijing: China Agricultural Science and Technology Press, 1999. p 147[本文引用:2]
[19]	Fan M, Jiang R, Liu X, Zhang F, Lu S, Zeng X, Christie P. Interactions between non-flooded mulching cultivation and varying nitrogen inputs in rice-wheat rotations. Field Crops Res, 2005, 91: 307-318[本文引用:2]
[20]	Feil B, Moser S B, Jampatong S, Stamp P. Mineral composition of the grains of tropical maize varieties as affected by pre-anthesis drought and rate of nitrogen fertilization. Crop Sci, 2005, 45: 516-523[本文引用:]
[21]	陈玉萍, 刘后利. 甘蓝型油菜子油分的积累与某些生理变化关系的研究. 武汉植物学研究, 1995, 13: 240-246 Chen Y P, Liu H L. Studies on the relationship between oil content and the change of biological metabolism in Brassica napus L. seed. J Wuhan Bot Res, 1995, 13: 240-246[本文引用:1]
[22]	Tian W N, Braunstein L D, Pang J, Stuhlmeier K M, Xi Q C, Tian X, Stanton R C. Importance of glucose-6-phosphate dehydrogenase activity for cell growth. J Biol Chem, 1998, 273: 10609-10617[本文引用:1]
[23]	西北农林科技大学. 基础生物化学实验指导. 陕西: 陕西科学技术出版社, 1986. pp 104-107 Northwest A&F University. Guide of Basic Biochemistry Experiment. Shanxi: Shaanxi Sci & Tech Press, 1986. pp 104-107(in Chinese)[本文引用:1]
[24]	Sebei K, Ouerghi Z, Kallel H, Boukhchina S. Evolution of phosphoenolpyruvate carboxylase activity and lipid content during seed maturation of two spring rapeseed cultivars (Brassica napus L. ). Comptes Rendus Biol, 2006, 329, 719-725[本文引用:1]
[25]	Edmeades D C. The long-term effects of manures and fertilisers on soil productivity and quality: a review. Nutr Cycl Agroecosyst, 2003, 66: 165-180[本文引用:1]
[26]	Steiner C, Teixeira W G, Lehmann J, Nehls T, de Macêdo J L V, Blum W E H, Zech W. Long term effects of manure, charcoal and mineral fertilization on crop production and fertility on a highly weathered Central Amazonian upland soil. Plant Soil, 2007, 291: 275-290[本文引用:1]
[27]	Zhao Y, Wang P, Li J, Chen Y, Liu S. The effects of two organic manures on soil properties and crop yields on a temperate calcareous soil under a wheat-maize cropping system. Eur J Agron, 2009, 31: 36-42[本文引用:1]
[28]	Zhu H, Wu J, Huang D, Zhu Q, Liu S, Su Y, Wei W. Improving fertility and productivity of a highly-weathered upland soil in subtropical China by incorporating rice straw. Plant Soil, 2010, 331: 427-437[本文引用:1]
[29]	Sui N, Zhou Z G, Yu C R, Liu R X, Yang C Q, Zhang F, Song G L, Meng Y. Yield and potassium use efficiency of cotton with wheat straw incorporation and potassium fertilization on soils with various conditions in the wheat-cotton rotation system. Field Crops Res, 2015, 172: 132-144[本文引用:1]
[30]	董合忠, 李维江, 唐薇, 张冬梅. 棉花生理性早衰研究进展. 棉花学报, 2005, 17: 56-60 Dong H Z, Li W J, Tang W, Zhang D M. Research progress in physiological premature senescence in cotton. Cotton Sci, 2005, 17: 56-60[本文引用:1]
[31]	杨铁钢, 黄树梅, 靳永胜, 孟菊茹, 刘凤玲. 棉株载铃量对其主要生育性状的影响. 华北农学报, 1999, 14(3): 65-70 Yang T G, Huang S M, Jin Y S, Meng J R, Liu F L. Effects of boll load in a cotton plant on major developmental traits. Acta Agric Boreali-Sin, 1999, 14(03): 65-70[本文引用:1]
[32]	Wakao S, Benning C. Genome-wide analysis of glucose-6- phosphate dehydrogenases in Arabidopsis. Plant J, 2005, 41: 243-256[本文引用:1]
[33]	Schwender J, Ohlrogge J B, Shachar-Hill Y. A flux model of glycolysis and the oxidative pentosephosphate pathway in developing Brassica napus embryos. J Biol Chem, 2003, 278: 29442-29453[本文引用:1]
[34]	陈锦清, 郎春秀, 胡张华, 刘智宏, 黄锐之. 反义PEP基因调控油菜籽粒蛋白质/油脂含量比率的研究. 农业生物技术学报, 1999, 7: 316-320 Chen J Q, Lang C X, Hu Z H, Liu Z H, Huang R Z. Antisense PEP gene regulates to ratio of protein and lipid content in Brassica napus seeds. J Agric Biotechnol, 1999, 7: 316-320[本文引用:1]
[35]	印南日, 李培武, 周海燕, 白艺珍, 丁小霞. 我国食用棉籽油质量安全. 中国农业科技导报, 2013, (4): 20-24 Yin N R, Li P W, Zhou H Y, Bai Y Z, Ding X X. Quality and safety of edible cotton seed oil in China. J Agric Sci Technol, 2013, (4): 20-24[本文引用:1]
[36]	董合忠, 李维江, 张晓洁. 棉花种子学. 北京: 科学出版社, 2004. pp 53-54 Dong H Z, Li W J, Zhang X J. Science and Technology of cotton seed. Beijing: Science Press, 2004. pp 53-54[本文引用:1]