Physiological response of flag leaf and yield formation of winter wheat under different spring restrictive irrigation regimes in the Haihe Plain,China

In order to identify the optimum period of spring water-restrictive irrigation for winter wheat(Triticum aestivum L.) in the Haihe Plain, China and elucidate its effects on flag leaf senescence and yield formation, field experiments were conducted at the Xinji Experimental Station of Hebei Agricultural University from 2016 to 2019 by using different irrigation regimes in spring, including the conventional regime involving two irrigation periods(control(CK), the 3-leaf unfolding stage and the anthesis stage) and a series of single, restrictive irrigation regimes(SRI) comprising irrigation at the 3-leaf unfolding stage(3 LI), 4 LI, 5 LI, and 6 LI. There are five major findings:(1) The senescence(determined by the green leaf area, GLA) in the 4 LI treatment occurred moderately earlier than that in CK, showed no significant difference with that in 5 LI and 6 LI, and occurred significantly later than that in 3 LI.(2) Compared with other SRI treatments, the GLA value and photosynthetic rate in 4 LI were 14.82 and 20.1% higher, respectively. Microstructural analysis of flag leaf also revealed that the mesophyll cells and chloroplasts were irregularly arranged under drought stress in 3 LI and 6 LI; however, drought stress had minimal negative effects on the microstructure in 4 LI and 5 LI.(3) Postponed irrigation in spring could significantly increase superoxide dismutase(SOD) and catalase(CAT) activities in the early stage of grain filling; however, these activities would subsequently decrease. Among the four SRI treatments, the overall enzyme activities were the highest in 4 LI, and the combined malondialdehyde(MDA) content in flag leaves in 4 LI and 5 LI was 14.5% lower on average than that in 3 LI and 6 LI.(4) The soluble sugar(SS) and proline(Pro) contents in 4 LI were the highest among the four SRI treatments; however, they were lower than those in CK. The abscisic acid(ABA) hormone content in 4 LI and 5 LI was lower than that in 3 LI and 6 LI, respectively, suggesting a smaller drought stress effect in 4 LI and 5 LI.(5) In two growing seasons, there was a larger number of spikes per unit area in 4 LI(i.e., 13.4% higher than that in 5 LI and 6 LI) and the 1 000-grain weight in 4 LI was the highest among the four SRI treatments(i.e., 6.0% higher than that in the other three SRI treatments). Therefore, a single restrictive irrigation regime at the 4-leaf unfolding stage is recommended to be effective in slowing down the senescence process of flag leaves and achieving high yield.     

高温胁迫对水稻剑叶净光合速率和叶绿素荧光参数的影响

对两个耐热性不同的水稻材料进行高温处理(8:00-17:00,37℃;17:00-8:00,30℃),研究了高温胁迫对水稻剑叶净光合速率和叶绿索荧光参数的影响.结果表明,高温胁迫下两个材料的剑叶光合速率迅速降低,热敏感的4628比耐热的996下降幅度更大.高温下 996 PSⅡ反应中心和天线系统受到的伤害轻,反应中心过...     

基于高光谱的小麦旗叶净光合速率的遥感反演模型的比较研究

植物净光合速率是植物生产的基础,是体现植物生长状况的重要生理指标。本文将小麦旗叶高光谱波段反射率进行一阶导数变换后与净光合速率（Pn）进行相关性分析确定敏感波段,分别采用二次多项式逐步回归（QPSR）、偏最小二乘法（PLSR）、BP神经网络法（BPNN）3种方法构建小麦旗叶的净光合速率反演模型,并对3种模型的预测精度进行比较分析。结果表明：（1）将小麦旗叶的原始光谱进行一阶导数变换后与Pn进行相关性分析确定的敏感谱区集中在750~925 nm之间,确定的6个敏感波段分别是：760、761、767、814、815、889 nm;（2）基于QPSR、PLSR、BPNN3种方法以及敏感波段的反射率一阶导数构建的Pn估测模型预测精度都较高,说明用这3种方法以及敏感波段对Pn的估测是可行的,其中模型估算能力顺序为QPSR > BPNN > PLSR,说明小麦旗叶Pn的最佳高光谱分析模型为小麦叶片750~925 nm反射率一阶导数变化后的QPSR模型。     

前氮后移施肥对冬小麦旗叶活性氧代谢和子粒产量的影响

１９９４－１９９６年高产冬小麦前氮后移施肥方式的产量效应和生理变化进行了研究。结果表明，采用此施肥方式可以减缓旗叶中超氧化物歧化酶活性下降和脂质过氧化产物丙二醛含量的积累，减少超氧阴离子的产生，提高旗叶片的叶绿素和蛋白质含量，延缓叶片衰老，显著增加穗粒重和产量。     

氮肥运筹及密度对中优752源库关系和剑叶温度的影响

以三系籼型杂交中稻中优752为材料,研究了氮肥运筹及密度对其源库关系和剑叶温度的影响。研究表明：在适宜施氮量的情况下,适当增加中后期施氮比例和适度稀植都能提高粒叶比和库源增量比、降低生育后期根系活力的衰退值,有利于源库协调。粒叶比和库源增量比与产量均显著正相关,生育后期根系活力的衰退值与产量极显著负相关。增施氮肥、增加中后期的施氮比例及适度稀植能降低剑叶温度。抽穗期及抽穗后25 d剑叶温度与产量呈极显著负相关,而抽穗期剑叶温度与抽穗期的伤流强度极显著负相关。     

穗肥施氮量对水稻剑叶生长及披垂的影响

以两优培九和国稻6号为材料,研究了水稻穗肥不同施氮量(0、45、90、135和180 kg/hm2)对剑叶生长和披垂程度的影响。结果表明,随着穗分化期施氮量的增加,水稻剑叶的长、宽和长宽比均相应增加,施氮对剑叶长度的影响大于叶宽。田间调查分析表明,剑叶长度与叶片披垂程度呈正相关。穗分化期增加施氮量,挺直叶片的比例下降,而披垂叶和极披叶的比例明显上升,剑叶的披垂系数也增加。国稻6号叶片披垂程度比两优培九大。     

高温胁迫对不同小麦品种光合性能的影响

选用不同品种小麦(弱春性品种淮麦30、半春性品种郑麦9023和半冬性品种烟农19),研究花后7d和花后15d高温对旗叶光合和叶绿素荧光特性的影响.结果表明,花后7～9d (T1)高温24 ℃/34℃(夜/昼)处理后,烟农19的净光合速率(Pn)、气孔导度(G0、PSⅡ最大光化学效率(Fv/Fm)、光化学猝灭系数(qP)、非光化学猝灭系数(qn)和光系统Ⅱ(PSⅡ)非循环光合电子传递速率(ETR)显著高于淮麦30和郑麦9023;郑麦9023的Pn、Ci和Fo显著高于淮麦30,胞间CO2浓度(Ci)显著高于烟农19;淮麦30的Ci、qp和qn显著高于郑麦9023.花后15d高温26 ℃/36℃(夜/昼)处理后,烟农19的Pn、Gs、Ci、Fv/Fm、qP、qn和ETR显著高于淮麦30和郑麦9023;郑麦9023的Pn、Gs、G、Fv/Fm、qP和ETR显著高于淮麦30;淮麦30的R显著高于郑麦9023和烟农19.花后7d和花后15d高温胁迫下,半冬性品种烟农19具有较高的光合活性和较强的自我保护机制,春性品种郑麦9023最低.     

Effect of nitrogen application during ripening period on photosynthesis and dry matter production and its impact on yield and yield components of semidwarf iniica rice varieties under water culture conditions

Abstract

A water culture pot experiment was conducted to analyze the effects of N application during the ripening period (RP) on photosynthesis, dry matter production, and its impact on grain ripening and yield in two semidwarf indica type varieties viz. Gui Zhao 2 (GZ) and BR3 (BR) compared with a japonica type variety Koganemasari (KO) under four N rates viz. 0 (N₀), 10 (N₁₀), 20 (N₂₀), and 40 (N₄₀) mg L^?1. Results showed that N application enabled to maintain a higher leaf area and delay leaf senescence in both indica and japonica type varieties but the decrease in the rate, of leaf area was higher in the former than in the latter and the rate was reduced with increasing N rates. Flag leaf photosynthesis and SPAD values of N treated plants were higher throughout the RP, showing the presence of a significant correlation either for each variety or all the varieties together. Higher photosynthetic rate was supported by higher leaf chlorophyll (SPAD value basis) content, stomatai conductance, and N concentration in leaf blades. Top dry matter content increased with increasing N rates mainly due to mean leaf area rather than NAR except for BR during RP but it was higher in KO than in GZ and BR. Reduction of shoot weight due to translocation of dry matter to panicles during RP was suppressed by N rates both in GZ and BR while shoot weight increased in the N-treated plants in KO. The dependency of KO on current photosynthates for panicle weight was found to be almost hundred percent while the contribution of stored carbohydrates in shoot before heading to panicle weight in GZ and BR was in the range of 4-27 and 33-54%, respectively and the rest was contributed by current photosynthates. The percentage increased with increasing N rates. Percentage of ripened grains (PRG) increased with increasing N rates in GZ and BR due to the increase in dry matter production and in the photosynthetic rates of apex leaves, despite the larger spikelet number and larger hull size. However, KO showed almost no variation although it had the highest PRG among the varieties. Brown rice yield followed the same pattern as that of PRG in GZ and BR and the highest yield was produced by BR followed by GZ and KO. These results suggest that N application during RP was more effective in increasing yield in the semidwarf indica type varieties than in the japonica type variety.