燕麦耐低磷胁迫的形态和生理响应机制

The lack of soil Phosphorus (P) is an improtant limiting factor that limit crop yields and quality. Oat is the special crop for food and feed in Inner Mongolia, is moderately sensitive to P deficiency. In the main oat producing areas of Inner Mongolia, most of the soil is calcareous soil, which have relative lower P utilization efficiency. In this subject, the abundant oat germplasm will be studied by solution culture and soil culture test, to investigate the extent of genetic variability in P efficiency and select for high and low P efficiency genotypes at early growth stages. Used the two genotypes, rhizo-box experiment, soil experiment and solution experiment will be conducted to study the root morphology, root P uptake kinetics, root exudates, photosynthetic characteristics and P re-utilization , moreover, the genotypic differences in root morphology and physiological mechanisms in response to low-P stress will be discussed. The results will be providing theoretical basis for the genetic law, molecular biology mechanism and breeding of P efficiency oat genotype and regulating in high P use efficiency. In addition, the studies are very important to guide rational fertilization, improve gene, alleviate environment pollution, promote sustainable agriculture and maintain stability of ecology system.

土壤有效磷的缺乏是作物产量和品质提高的重要限制因子，燕麦是内蒙古优势特色粮饲兼用作物，对缺磷敏感，且燕麦主产区多数土壤为石灰性土壤，土壤磷的利用效率相对更低，因此本研究对大量的燕麦种质资源采用苗期水培试验初筛、土培试验全生育期鉴定，明确不同燕麦品种的磷效率，获得极端磷高效和磷低效品种；并以此为试材，设计不同磷素水平的根箱、土培和水培实验，从根系形态、根系磷素吸收动力学特性、根系分泌物改变、植物內源激素及植物体内磷运转和再利用方面，较系统地探讨不同磷效率燕麦品种对低磷胁迫的根形态变化和生理响应差异，以揭示燕麦对低磷的适应机制，为燕麦磷高效调控、磷高效遗传规律及磷高效品种的选育提供理论依据。对燕麦生产的合理施肥、磷营养性状的遗传改良、农业生产的可持续发展，减轻环境污染及维持生态系统的稳定具有十分重要的现实意义。

土壤有效磷的缺乏是作物产量和品质提高的重要限制因子，燕麦是内蒙古优势特色粮饲兼用作物，对缺磷敏感，且燕麦主产区多数土壤为石灰性土壤，土壤磷的利用效率相对更低。本研究探讨了不同磷效率燕麦品种适应低磷胁迫的根形态变化和生理响应差异，主要研究结果有：（1）筛选到燕科1号、925、V7和白燕5号4个典型磷高效品种，2个典型磷低效品种莜麦4400 和MARION。（2）低磷胁迫显著降低燕麦的生物量、磷累积量、籽粒产量和磷效率系数，磷高效品种的籽粒产量、籽粒中磷累积量、磷转运系数显著高于磷低效品种。磷高效品种根际土壤pH低于磷低效品种，具有较强的根际酸化能力。不同磷效率品种低磷胁迫下各土层酸性磷酸酶活性均较低，磷高效品种根际土壤酸性磷酸酶活性显著高于磷低效品种。低磷胁迫下，根际土壤的各种磷组分含量显著减少，磷高效燕麦品种的各种磷组分的耗竭多于磷低效品种。（3）燕麦磷高效品种通过增加根系总长、根系表面积、根系体积和最大根长，来适应低磷胁迫。磷高效品种具有高的Imax，低的Cmin和Km。（4）三种无机磷源对两种燕麦品种的有效性为K-P>Al-P>Fe-P；燕麦磷高效品种活化吸收土壤中NaOH-Pi、dil.HCl-Pi的能力强于磷低效品种；燕麦磷高效品种对三种单一磷源的吸收效率均高于磷低效品种，对磷的活化利用差异表现在2种难溶磷源上。低磷胁迫下,磷高效品种根系分泌的质子和有机酸的量均比磷低效品种多，能够活化并利用土壤中难溶性无机磷。（5）磷高效品种的根冠比、根际土壤有效磷含量显著低于磷低效品种，磷高效品种利用植酸态有机磷能力高于磷低效品种。低磷胁迫下，磷高效品种根系、下部叶分泌的酸性磷酸酶活性显著高于磷低效品种。（6）低磷胁迫显著降低了燕麦叶片ZR、ABA和GA3含量，增加了IAA的含量；HP和LP处理下，随生育时期的推进燕麦叶片ZR、ABA和IAA含量均呈“先升后降”的变化趋势，GA3含量呈“先降后升”的变化趋势。以上结果将为燕麦磷高效调控、磷高效遗传规律及磷高效品种的选育提供理论依据。