播种时间对豫北地区小麦农学指标、生理指标及产量的影响

作物产量存在着明显的年际变化,为解析播种时间对小麦产量可能带来的影响,在中国科学院封丘农业生态试验站利用原位盆栽试验,研究了播种时间对小麦产量的影响以及小麦产量与关键农学指标和生理指标的关系。试验包括4个播种时间处理:10月5日(T1)、10月10日(T2)、10月15日(T3)和10月20日(T4)。结果表明:在豫北地区,T2处理的小麦产量最高。T2处理的小麦有效穗数和穗粒数分别为38.00穗.盆-1和37.67粒.穗-1,显著高于其他处理。相关分析表明,小麦产量与有效穗数和穗粒数呈极显著正相关,说明播种时间主要通过改变有效穗数和穗粒数等农学指标影响小麦产量。早播提高了小麦根系活力,但其他生理指标呈现出不同的响应特征。分蘖期各处理中小麦叶绿素含量无显著差异,但拔节期后,T2处理的小麦叶绿素含量显著高于T3和T4处理。T1和T2处理硝酸还原酶活性随着小麦生长不断增加,T3和T4处理则在整个生长期处于相对稳定水平,开花期,T2处理小麦硝酸还原酶活性高达57.12 g·g-1(FW)·h-1,极显著高于其他处理。植株硝态氮含量随小麦生长呈下降态势,拔节期T2处理小麦硝态氮含量最高,开花期各处理硝态氮含量差异不明显。分蘖和拔节期各处理小麦植株磷酸酶活性差异不显著;到开花期T2处理达到最大值,为0.34mg·g-1(FW)·h-1,显著高于T3和T4处理,但与T1处理之间差异不显著。小麦产量与拔节期植株硝酸还原酶和酸性磷酸酶活性、开花期硝酸还原酶活性显著正相关,播种时间可能通过改变不同生育期小麦植株硝酸还原酶和酸性磷酸酶活性最终影响产量。

Effect of sowing date on agronomic, physiologic and yieldindicators of wheat in North Henan Province

To understand inter-annual variability in grain yield, a pot experiment was conducted to evaluate the effect of sowing date on agronomic, physiologic and yield indicators of wheat. The four sowing dates were October 5 (T1), 10 (T2), 15 (T3) and 20 (T4). Agronomic indicators of the numbers of productive spike and grains per spike, and the 1000-grain weight were measured after wheat harvest. Also physiologic indicators of root activity (RA), acid phosphatase (APA) and nitrate reductase (NRA) activities were measured during wheat growth season. Results indicated that sowing date had significant influence on grain yield and wheat yield was highest for the October 10 (T2) sowing date. Wheat absorptive capacities in nitrogen and phosphorus in T2 treatment were much higher than in other treatments. Productive spikes and grains per spike in T2 were 38.00 tiller·pot 1 and 37.67 grain·spike 1, respectively, also significantly higher than those in other treatments. Productive spikes and grains per spike were positively correlated with wheat yield. While no differences in chlorophyll contents were noted among treatments at tillering stage, it was significantly higher in T2 than in T3 and T4 treatments at jointing and flowering stages. Nitrate reductase activity (NRA) increased with wheat growth in T1 and T2, but remained relatively stable in T3 and T4 treatments during the entire growth period. The activity of nitrate reductase was up to 57.12 g·g^-1(FW)·h^-1 at flowering stage in T2 treatment, significantly higher than those in other treatments. Nitrate content decreased with increasing wheat growth in the treatments. It was highest in T2 at jointing stages, and no significant differences noted among treatments at flowering stage. Acid phosphatase activity (ARP) was about 0.28 mg·g^-1(FW)·h^-1 in all treatments at tillering and jointing stages. It was up to 0.34 mg·g^-1(FW)·h^-1 in T2 at flowering stage, which was significantly higher than in other treatments. In the study, wheat root activity (RA) decreased with delay in sowing date. Analysis showed significant correlation between grain yield and numbers of productive spikes or gains per spike. Also wheat yield was significantly correlated with APA and NRA at jointing stage, and with aboveground biomass and NRA at the flowering stage. The findings of the study suggested that sowing date influenced wheat yield mainly through changing APA and NRA. Also soil N and P absorption varied with sowing date, which in turn caused variations in wheat yield.