花生钙效率差异机制及调控

Calcium (Ca) uptake is next to nitrogen, higher than phosphorus and equivalent to potassium in peanut plant. Under Ca stress, development of peanut seed is retarded and the numbers of hollow and immature pod increase, which result in yield reducing. In recent years, the rapidly increasing incidence of hollow pod has become one of the main factors which influences peanut yield in our country. Ca efficiency of peanut with different genotypes presents extensive genetic diversity. This study is based on the previous screening of peanut variety with Ca high efficiency. Applying Ca fertilizer to root zone and pod zone respectively by segregation apparatus of root and pod combined with 45Ca tracer technique are used to: (1) investigate the characteristic of Ca absorbing and utilizing for root and pod and redistribution of store Ca in stem and leaf, quantitative analysis using potential, compensatory effect and the contribution rate to seed formation for the three Ca sources of “root Ca”, “pod Ca” and “store Ca in stem and leaf”; (2) discuss morphological and structural difference of root and pod and their adaptive mechanism to Ca stress; (3) clarify the relationship between endogenous hormone and Ca efficiency, and explore the regulating effect of endogenous hormones on Ca efficiency. Based on this project, we will reveal the physiological mechanism and regulating effect on Ca efficiency of different peanut genotypes from three respects of Ca nutritive peculiarity, form and structure of root and pod and hormone metabolism of plant. We also explore the possibility and approach of relieving Ca stress by applying hormones or hormone inhibitors, which have important theoretical value and practical significance for selecting and breeding Ca high efficiency variety and high efficient Ca-applying.

花生对钙的吸收量仅次于氮，高于磷，与钾相当。钙胁迫导致花生籽仁发育受阻，荚果出现空、秕而减产。近年来，花生空壳发生率陡增，已成为影响我国花生产量的主要因素之一。不同基因型花生耐低钙能力（简称钙效率）呈广泛遗传多样性。本项目在前期花生钙高效品种筛选的基础上，通过根荚分离装置，向根系层和结实层分别供钙，结合45Ca示踪技术，研究产量形成期不同钙效率品种根系、荚果对钙吸收、利用及茎叶贮藏钙的再分配特点，量化不同钙效率花生根、荚、冠（茎叶）三种钙源利用潜力、相互间补偿效应及对籽仁形成的贡献率；探讨不同钙效率品种根、荚形态结构差异及其对钙胁迫的适应机制；阐明植株内源激素与钙效率的关系及调控效应。从钙营养特征、根荚形态结构及激素代谢三方面，揭示不同基因型钙效率差异生理机制及调控机理，探索外施激素或抑制剂缓解钙胁迫的可能性及途径，为花生钙高效品种选育及高效施钙提供依据。

花生是钙吸收量较高的作物，缺钙导致花生籽仁发育不良，空、秕和烂果增加。近年来，由土壤钙胁迫导致的花生荚果空秕现象陡增，钙胁迫已成为影响我国花生产量、品质和效益的主要因素之一，亟待解决。种植钙高效吸收利用（钙高效）遗传潜力的花生品种可作为缓解钙胁迫的有效途径。因此本项目以不同钙效率花生品种为研究对象，从钙营养特征、根荚形态结构及激素代谢三方面研究不同基因型花生钙效率差异的生理机制。（1）通过根荚分离装置，向根系层和结实层分别供钙，并结合45Ca示踪技术研究表明，结实层缺钙时，钙高效品种荚果直接吸钙能力强于钙低效品种。两品种荚果吸收的钙均能向营养体中转移，在一定程度上弥补根系吸钙不足，而根系吸收的钙向荚果中转移量较小。（2）采用盆栽及大田试验研究表明，缺钙时两品种珠柄细弱、木质部散生，维管数量少且分布散乱；缺钙导致果皮木栓形成层变大、内外薄壁细胞增多，子叶细胞体积变小，内含物和维管束减少，不利于营养物质向籽仁转运。缺钙并未抑制花生根系生长，却降低了钙低效品种植株氮、钙积累量和荚果钾累积量及干物质重，钙高效品种对缺钙的反应不敏感，植株养分含量及产量并未显著降低。（3）盆栽试验结果表明，外源施用生长素提高了钙低效品种荚果生长素含量，促进荚果发育，有效控制冗余生长，提高了荚果氮累积量及收获指数，增产效果显著；而施用生长素抑制剂不利于花生根系生长发育及钙钾元素吸收，最终降低花生产量；施用赤霉素促进了花生地上部生长，但抑制了荚果钙素吸收及干物质累积，导致营养生长和生殖生长比例失调，显著降低产量；施用赤霉素抑制剂不利于植株生长发育及养分吸收，其中对荚果的影响更大。因此外施生长素是促进钙低效品种生殖生长，缓解钙胁迫的重要手段。研究结果为花生钙高效品种选育及高效施钙提供依据。