黄土高原冷凉区苦荞根系抗旱耐瘠生理生态机制研究

Tartary buckwheat (Fagopyrum tataricum) is an important medicine-food minor grain crop originating in China. It has prominent location advantage and production superiority in cold areas of the Loess Plateau. Elucidating the ecophysiological mechanism of stress resistance and associated regulatory mechanism in the root system of tartary buckwheat can help to improve the production and quality of this crop. Thus far, little research has investigated the ecophysiology of stress resistance in tartary buckwheat. In this study, we propose to perform iron-wire-net box culture, rhizobox culture, soil column culture, pot culture, field rainproof-shed experiment, and laboratory analysis, using a combination of traditional research techniques with image analysis, electron microscopy, gel electrophoresis, and laser scanning confocal microscopy. We will determine the quantitative characteristics of roots and their relationship with ecophysiological parameters of stress resistance in tartary buckwheat under drought and low-fertility stress. On this basis, we will analyze root growth pattern of tartary buckwheat and describe similarities or differences in root characteristics in terms of growth, architecture, molecular cytology; exudation, nutrient uptake kinetics, and water–fertilizer utilization; and relevant physiological indices and yield formation between different stress-resistant varieties under drought and low-fertility conditions. Further, we will elucidate the ecophysiological mechanism of drought resistance and low-fertility tolerance in the root system, find out root management strategies for improving stress resistance and enhancing grain yield, and screen out root indices for high-yield and stress-resistant variety selection in tartary buckwheat. The results will provide a reference for breeding and cultivation of tartary buckwheat on the Loess Plateau.

苦荞是黄土高原冷凉区重要的食药两用杂粮作物，在该区具有明显的区位和生产优势，但有关苦荞抗逆生理生态方面的研究尚不多见。研究其根系抗逆机理及其调控机制，进而提高其产量与品质，在理论和实践上均具有十分重要的意义。本研究拟采用网状铁丝箱栽培、根箱栽培、根管栽培、盆栽试验、大田旱棚试验与室内分析相结合的方法，试图通过传统研究技术及图像分析、电镜观察分析、电泳分析、激光共聚焦显微观察等手段，对干旱、瘠薄逆境胁迫条件下苦荞根系量性特征及其与抗逆生理生态的相关性进行定量研究，探讨苦荞根系的生长规律及旱、薄逆境胁迫下不同耐性品种的根系生长特性、构型特点、分子细胞学特征、根际分泌物数量与养分吸收动力学特点、水肥利用能力和相关生理指标与产量形成的异同点，阐明其抗旱耐瘠的生理生态机制，寻求增强苦荞抗逆能力、提高苦荞产量的根系调控措施及高产、抗逆苦荞品种选育的根系指标，为黄土高原地区苦荞育种和栽培提供理论依据。

起源于我国的药食两用杂粮类作物苦荞，在黄土高原冷凉区具有明显的区位和生产优势，但目前有关苦荞抗逆性生理生态方面的研究尚不多见。本研究采用网状铁丝箱栽培、根管栽培、盆栽试验、大田旱棚试验与室内分析相结合的方法，对干旱、瘠薄（低氮、低磷）逆境胁迫下苦荞根系量性特征及其与抗逆生理生态的内在联系进行了定量研究，结果表明：1）苦荞根表面积、最大根长等指标在测定时期内随时间的变化均符合指数函数，而根体积、MDA 含量等指标与一元二次方程函数的变化规律一致。2）干旱胁迫下，苦荞IAA含量显著降低，ABA含量显著升高，干旱后复水有效地缓解了干旱对内源激素的影响。株高、茎粗、根冠比、根系活力、最大根长、MDA、 Fo 及水势等指标，可作为苦荞抗旱特性的快速鉴定指标。此外，适量施磷有利于提高苦荞植株抗旱性，促进植株生长发育和产量形成。3) 不同品种苦荞对低氮胁迫的响应存在显著差异。耐低氮能力强的苦荞品种通过调节土壤酶活性来适应低氮的生长环境，并可能通过此种方式来改变其对碳源的偏好。苦荞也可能通过根系有机酸的分泌来调节根际土壤养分有效性以应对低氮胁迫。株高、茎粗、叶面积、根冠比、叶绿素含量、最大荧光产量（Fm）、根系超氧化物歧化酶(SOD)活性及氮利用效率等8项指标可用于耐低氮苦荞基因型的快速鉴定。4）耐低磷品种苦荞通过主根伸长下扎以及增加酸性磷酸酶分泌量，以促进对土壤磷素的吸收与利用。根表面积、根长、株高、地上部干质量、酸性磷酸酶、磷积累量、过氧化物酶活性等７项形态与生理指标，可用于苦荞苗期耐低磷能力的快速鉴定。5）适当的氮磷肥配施具有明显的正加和效应，但过量施肥也有导致增产幅度下降的风险，在本试验条件下，中氮高磷（施纯Ｎ量0.1g/kg，施P2O5量0.2g/kg）配施效果最优。本研究探明了苦荞抗旱、耐瘠（低氮、低磷）的快速鉴定指标，揭示了苦荞抗旱耐瘠的生理生态机制，筛选出适合黄土高原苦荞高产的氮磷配施量，可以为黄土高原地区苦荞育种和栽培提供理论依据。