摘要
摘要:向日葵列当（Orobanche cumana Wallr.）是一种根寄生草本植物，对向日葵等经济作物造成严重危害。为了减少向日葵列当对向日葵的寄生，降低土壤中向日葵列当种子库，本试验以新疆地区广泛种植的玉米品种‘京糯一号’和‘新玉57号’为研究材料，通过穴盘试验研究在不同时期（出苗后10 d和15 d）施加两种不同浓度赤霉素（10^-4mol·L^-1和10^-5mol·L^-1）对上述两个品种玉米生长发育和分泌列当萌发刺激物质的影响；24 d后收集并提取玉米根系分泌物，用其进行刺激向日葵列当种子的萌发试验，从而筛选出刺激向日葵列当种子萌发能力较强的玉米品种进行盆栽试验。通过盆栽试验，在玉米种植后的不同时期（20 d和40 d）喷施10^-4mol·L^-1赤霉素以探究玉米与赤霉素共同防除向日葵列当种子的效果，收获时（105 d后）采集玉米地上部、根和根际土样品，用其甲醇浸提液刺激向日葵列当种子萌发；次年在种植过玉米的盆中种植后茬作物向日葵，收获时测定向日葵的农艺指标并统计向日葵列当的出土数。结果表明：穴盘试验中施加赤霉素对玉米的株高有显著增高作用，对玉米根系分泌萌发刺激物质没有抑制作用，即在玉米生长时期可以施加10^-4mol·L^-1和10^-5mol·L^-1赤霉素。此外，‘新玉57号’根系分泌物的100倍稀释液刺激向日葵列当种子的萌发率显著高于‘京糯一号’，因此选取‘新玉57号’作为盆栽试验的玉米品种。盆栽试验中不同时期施加10^-4mol·L^-1赤霉素，玉米株高同样显著高于对照，增长率分别为22.5%、19.1%。次年种植后茬作物向日葵，在第20 d向玉米施加赤霉素处理的盆中种植的向日葵的花盘直径比对照（种植玉米时不施加赤霉素）显著增加57.1%。与对照相比，在种植玉米后的20 d和40 d施加赤霉素的处理种植向日葵，向日葵列当的出土数分别是1.3个·盆^-1、1.8个·盆^-1，分别降低76.4%和67.3%。因此，可以在玉米种植的后20 d和40 d施加10^-4mol·L^-1赤霉素，与玉米共同诱导向日葵列当种子“自杀发芽”，以减少向日葵列当对向日葵植株的危害。
关键词:向日葵列当/
种子萌发/
玉米/
赤霉素/
根系分泌物
Abstract:Sunflower broomrape (Orobanche cumana Wallr.) is a parasitic, herbaceous root plant that has severe effect on industrial crops like sunflower. In order to reduce the parasitic effect of sunflower broomrape on sunflower and sunflower broomrape seed bank, two generalized maize varieties ('Jingnuo No. 1', 'Xinyu No. 57') in Xinjiang Uygur Autonomous Region of China were used in a plug tray experiment to study the effects of application of two exogenous concentrations of gibberellin acid (10^-4 mol·L^-1 and 10^-5 mol·L^-1) at different periods (10 d and 15 d after germination) on maize growth and development, and secretion of stimulant of sunflower broomrape seed germination. The study screened out more capable maize variety for pot experiment by collecting and extracting root exudates of maize to stimulate sunflower broomrape seed germination after 24 days. Through applying GA₃(10^-4 mol·L^-1) at different times after planting, the study also explored the combined effects of maize and GA₃ on controlling sunflower broomrape seeds. Thus in the pot experiment, GA₃ was exogenously applied 20 and 40 days after planting maize, and plant samples (leaves, stems and roots) and rhizosphere soils collected at harvest (105 d) were used to further analyze sunflower broomrape seed germination. Sunflowers were planted in pots that were planted with maize in the past years. The epigaeous number of sunflower broomrape was counted and sunflower plants of agronomic index measured at harvest. The results showed the application of GA₃ in the plug tray experiment had a significant effect on maize height. In addition, there was no inhibiting effect on maize in terms of secreting germination stimulant of sunflower broomrape. Thus, it was productive to apply GA₃(10^-4 mol·L^-1 and 10^-5 mol·L^-1) during maize growth period. Moreover, 100-dilution of root exudate of 'Xinyu No. 57' maize variety showed more significantly stimulating effect on sunflower broomrape germination rate than 'Jingnuo No. 1', 'Xinyu No. 57' was finally used in the pot experiment. In the pot experiment, maize heights under 10^-4 mol·L^-1 GA₃ application after 20 and 40 days of maize planting were higher than that under the control (no application of GA₃), with respective increases of 22.5% and 19.1%. Sunflower was planted in the second year after maize, which was treated by GA₃at 20 days after planting. The diameter of sunflower disk increased by 57.1% compared with the control. Compared with control, the number of epigaeous sunflower broomrape was 1.3·plot^-1 and 1.8·plot^-1, which suggested decreases of 76.4% and 67.3%, respectively. In conclusion, the application of 10^-4 mol·L^-1 GA₃ to maize after 20 and 40 days of planting stopped sunflower broomrape seed germination and thereby reduced sunflower broomrape damage to sunflower.
Key words:Sunflower broomrape/
Seed germination/
Maize/
Gibberellin acid/
Root exudate



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