不同播期冬小麦小花发育特性与同化物代谢的相关性

【目的】推迟播期能够维持单位面积粒数已在前期研究中得到证实，本研究进一步探讨不同播种期冬小麦小花发育特征及分化、退化的差异性，分析植株同化物积累、分配与小花发育和结实的关系，旨在为提高小麦穗粒数以及丰富小麦高产栽培理论提供参考。【方法】试验于2014—2015年和2015—2016年连续两个小麦生长季，在山东省泰安市岱岳区大汶口镇东武村山东农业大学试验田 (35°57′N，117°3′E) 进行，以泰农18和济麦22为试验材料，设置9月24日、10月1日、10月8日、10月15日和10月22日共5个播期处理，观察记载小花发育过程中分化和退化数量动态以及最终结实粒数，测定开花期穗部和茎秆的干物质和氮素积累量，计算小花退化阶段整株和穗部的干物质和氮素积累速率。【结果】播期推迟条件下，单位面积可孕花数和单位面积结实粒数获得了维持，单位面积最大分化小花数明显降低，小花存活率显著提高。推迟播期明显减少了小花退化数量，小花退化速率明显降低。在小花退化阶段，推迟播期加速了整株和穗部的干物质和氮素积累，从而为开花期穗干重的维持以及干重穗茎比和氮素穗茎比的提高提供了保证。相关分析表明，开花期单位面积可孕花数分别与穗干物重、干物重和氮积累量穗茎比、整株和穗的干物质和氮的积累速率以及小花存活率均呈极显著正相关。推迟播期明显减少了有效茎蘖和无效分蘖所产生的退化小花数，尤其无效分蘖产生的退化小花数下降幅度更加明显。提高主茎在群体中同化物所占比例能够有效维持单位面积可孕花数和减少退化小花数，降低了小花死亡消耗。此外，推迟播期提高了可孕花累积生长度日生产效率，降低了退化小花累积生长度日生产效率。【结论】推迟播期明显降低了小花的退化，从而提高了小花存活率，开花期单位面积可孕花数的维持与植株同化物代谢密切相关。适期晚播提高了主茎在群体中的比重，有利于减少无效消耗和提高资源利用效率。

Correlation between floret development characteristics and photosynthate metabolism of winter wheat in different sowing dates

【Objectives】Our previous work confirmed that grain number per unit area could been maintained through delaying sowing date. This study further investigated the development characteristics of florets and compared their differences in differentiation and degradation under different sowing dates, and analyzed the relationship between photosynthate accumulation and distribution and floret development and grain setting. The purpose was to provide references for wheat high-yield cultivation.【Methods】Field experiments were conducted during the 2014?2015 and 2015?2016 at the Experimental Station of Dongwu Village (35°57′N, 117°3′E), Shandong Province, China. Two wheat cultivars of Tainong18 and Jimai22 were planted as the experimental materials. Winter wheat was sowed on September 24, October 1, 8, 15 and 22, respectively. Binocular microscope was used to record the dynamics of differentiation and degeneration during the floret development. The final grains number, the dry matter and nitrogen accumulation of spikes and stems at anthesis were investigated, and the accumulation rate of dry matter and nitrogen in the whole plants and spikes during the floret degeneration stage were calculated.【Results】Among the five sowing date treatments, the number of fertile florets and final grains per unit areas were maintained same, but the maximum number of differentiated florets per unit area was significantly reduced, and the survival rate of florets was significantly increased. When the sowing date was delayed, the degenerated rate of florets was significantly reduced. The accumulation of dry matter and nitrogen in the whole plants and spikes were significantly accelerated during the floret degeneration stage, thus ensure the constant spike dry weight and the ratios of dry matter and nitrogen between spikes and stems at anthesis. The number of fertile florets at anthesis exhibited significant and positive correlations with spike dry matter weight, the ratios of dry matter weight and nitrogen accumulation of spike/stem, and the accumulation rate of dry matter and nitrogen in the whole plants and spikes and survival rate of fertile florets, respectively. The number of degenerated florets per square meter produced by effective stems and ineffective tillers significantly reduced as a response to delay sowing date, and the number of degenerated florets per square meter produced by ineffective tillers was even more significantly decreased. Enhanced the proportion of the main shoots in the population of photosynthate can be in favor to maintain the number of fertile florets and decrease the number of degenerated florets, and reduce the depletion of florets death. In addition, the growing degree day production efficiency of fertile florets increased and the growing degree day production efficiency of degenerated florets reduced as a result of delaying the sowing date.【Conclusions】Delayed the sowing date could increase the survival of florets through inhibiting the floret degeneration. The maintenance of the number of fertile florets is closely related to the photosynthate metabolism of plant. Delaying the sowing date could increase the proportion of the main stem in the plant population, which is beneficial to reduce the invalid consumption and improve the utilization efficiency of resource.