施肥对旱地全膜覆土穴播荞麦倒伏的影响及其生理机制

Buchwheat (Fagopyrum esculentum Moench. L.) is a special dominant crop in arid areas of Northwest China,Hole-sown planting integrated with complete plastic mulching has been proposed as a supporting technique for boosting buckwheat yield in the regions. However, lodging is a major limiting factor closing the buckwheat yield gaps and improving buckwheat grain quality. Currently, it is still unclear about the regulation mechanism of plastic mulching and fertilization levels on buckwheat lodging. A long-term located experiment will be carried out to investigate the effects of different fertilization application rates on snapping resistance parameters, vascular bundle structures, lignin content and key synthases (PAL, TAL, 4CL, and CAD) activities of buckwheat root and stem systems, the lodging index, and the dynamics of soil moisture and nutrients. The effects of fertilization management on lodging resistance of buckwheat stems will be further discussed to analyze the relationships among enzyme activities and snapping resistance parameters and lodging indexes. At the same time, the effects of fertilization management on lodging resistance of buckwheat stems will be further discussed. The study is of important significance to elucidating the physiological mechanism of lodging buckwheat with complete plastic mulching, and identifying an optimal nutrient management regulation technique for lodging resistance of buckwheat on the dry land of Northwest China.

荞麦是西北旱作区主要的特色作物，全膜覆土穴播是西北半干旱区荞麦增产的保障性技术，但倒伏是限制全膜覆土穴播荞麦品质和产量潜力挖掘的关键因素，目前对其水肥调控机制尚不明确。本研究依托大田定位试验，测定不同养分水平下全膜覆土穴播荞麦在分枝期、开花期、乳熟期的根茎形态、抗折指数、维管束结构、茎秆木质素含量及其苯丙氨酸解氨酶、酪氨酸解氨酶、肉桂酰CoA还原酶、肉桂酸醇脱氧醇4种关键酶的活性、倒伏指数以及土壤水分和养分等指标。研究地膜覆盖和养分管理措施对荞麦倒伏性状的影响，分析茎秆木质素含量及其关键酶活性—抗折系数—倒伏指数之间的关系，探讨养分管理对荞麦茎秆抗倒伏能力的生理成因，揭示全膜覆土穴播对荞麦根茎形态学、力学、解剖学特征及生理生化成分的影响及其倒伏的作用机制，这一研究对阐明全膜覆土穴播荞麦倒伏发生的生理机制、以及探求养分管理调控荞麦抗倒伏能力的技术途径有重要意义。

荞麦是西北半干旱区主要的杂粮作物，全膜覆土穴播技术在旱地荞麦生产具有增产增效作用，倒伏严重影响了全膜覆土穴播荞麦品质和产量的提高，目前对其水肥调控机制尚不明确。本研究依托大田定位试验，主要研究地膜覆盖和养分管理措施对荞麦倒伏性状的影响，分析茎秆木质素含量及其关键酶活性—抗折系数—倒伏指数之间的关系，揭示全膜覆土穴播对荞麦根茎形态学、力学、解剖学特征及生理生化成分的影响及其倒伏的作用机制。.研究结果表明，在半干旱区，荞麦全膜覆土穴播结合减量施肥处理(MLF，纯N 40 kg hm–2 + P2O5 30 kg hm–2 + K2O 20 kg hm–2)能够促进荞麦植株对土壤水分和养分的吸收，显著增加单株粒重及籽粒饱满率，进而显著增加生物量和产量，降低倒伏率。施肥和覆膜显著增加荞麦地上鲜重、地上干重、根干重、根体积、主根粗、主根长、根体积，提高根冠比等与倒伏率显著相关的农艺指标。地膜覆盖不同程度增加了荞麦皮层纤维组织和维管束厚度及细胞层数，茎秆维管束数量越多、越厚，厚壁组织细胞层数越多，皮层纤维组织越厚，就越能增强荞麦茎秆的抗折力和抗倒伏能力。地膜覆盖还增加了荞麦茎秆中的苯丙氨酸解氨酶（TAL）、酪氨酸解氨酶（PAL）、肉桂酰CoA还原酶（CAD）、肉桂酸醇脱氧醇（4CL）活性，提高了茎秆的木质素积累量，提高茎秆抗折力参数、降低倒伏指数，增强荞麦抗倒伏能力。结果表明，MLF处理能够降低荞麦植株重心高度和第2茎节长，根系大，侧根数目多，茎秆质量大，茎秆第2节间长度较短，根冠比大，其倒伏指数小，茎秆抗折力参数大，抗倒伏能力强，显著降低倒伏率。综上，全膜覆土穴播减量施肥处理较其它处理具有抗倒伏、增产的明显效果。本研究分析了半干旱区全膜覆土穴播荞麦根茎形态、力学和解剖学及生理生化特性变化，阐明施肥水平对荞麦倒伏的生理调控效应。在解决科学问题的基础上探索技术应用途径，对探明半干旱区荞麦的抗倒伏性能及其调控途径，揭示半干旱区荞麦高产抗倒的生理机制及其关键栽培技术措施有重要的意义。