提高立体匀播冬小麦光合效能和产量的最佳追氮时期

【目的】立体匀播技术作为一种新型的播种方式,与之相配套的氮肥运筹技术尚不成熟,在某种程度上制约了其增产潜力的发挥。研究合理的播种方式与氮肥运筹组合,可为实现良种良法配套提供科学依据。【方法】于2017-2018年在中国农业科学院作物科学研究所赵县试验农场,以两个中筋小麦品种衡观35和邯6172为试验材料,进行了三因素裂区田间试验。主区为立体匀播(C1)和常规条播(C2)两种播种方式。副区为4个氮肥追施时期:拔节始期(T1)、拔节后10天(T2)、拔节后20天(T3)、开花期(T4),追氮量均为120kg/hm^2。副副区为两个小麦品种。开花期及花后每7天用SPAD-502Plus型叶绿素仪测定旗叶SPAD值,共测5次,测定部位为顶部、中部、基部各一次,取平均值。于小麦开花当天开始,用LI-6400XT便携式光合仪测定旗叶的相关光合参数,共测5次。于成熟期考察小麦株高、穗粒数、千粒重、穗长,实收测产。【结果】两个小麦品种的单位面积穗数和籽粒产量均在立体匀播条件下T2处理达到最高,且在相同追氮时期下高于常规条播;而千粒重均在立体匀播条件下T4处理最高。同一播种方式下,衡观35拔节始期追氮植株株高达到最高值,邯6172于T2处理追氮达到最高值;而两个小麦品种的穗长和小穗数达到最佳值的追氮时期因播种方式的不同存在一定的差异。在4个追氮时期下,立体匀播小麦的旗叶SPAD值、净光合速率均高于常规条播,其中在花后7天和21天时T2、T3处理追氮旗叶净光合速率均显著高于T1处理追氮。两个小麦品种间的旗叶SPAD值在整个灌浆期间均表现为显著差异,而旗叶净光合速率主要表现在开花当天至花后7天差异显著。与此同时,两个播种方式下小麦旗叶SPAD值和净光合速率均随着追氮时期的后移呈现逐渐增加的趋势。【结论】在立体匀播条件下拔节后10天追施氮肥有利于植株单株营养均衡,促进根系发达,易建成优势蘖群体,有利于单位面积穗数的提高和最终产量的增加。

Optimum nitrogen topdressing time for improving photosynthetic efficiency and yield of tridimensional uniform sowing winter wheat

【Objectives】Tridimensional uniform sowing (TUS) is currently extended sowing method of winter wheat, the matching nitrogen fertilization has not yet been studied. The research compared the effect of topdressing time on the photosynthesis efficiency and grain yield of winter wheat, to provide reference for academic and efficient nitrogen fertilization specified for the tridimensional uniform sowing.【Methods】Winter wheat field experiments with 3 factors split block design were conducted in the Experimental Farm of the Institute of Crop Sciences, Chinese Academy of Agricultural Sciences in Zhaoxian, Hebei Province, China in 2017–2018. The main block was tridimensional uniform sowing and sowing in drill; the subblock was four topdressing time of nitrogen at the initial jointing stage (T1), 10 days after jointing stage (T2), 20 days after the jointing stage (T3) and anthesis stage (T4); the sub-sub-block was two wheat cultivars of Hengguan-35 (HG35) and Han-6172 (H6172). During the anthesis stage, the SPAD values of flag leaves were measured using SPAD-502 Pluschlorophyll meter and the net photosynthetic rates were measured using LI-6400XT portable photosynthesizer. At maturity stage, the ear number per unit area, 1000-grain weight and the yield of wheat were investigated.【Results】The highest panicle number and grain yield were achieved in T2 treatment for tridimensional uniform sowing of two wheat varieties, and the highest 1000-grain weight were T4 treatment for tridimensional uniform sowing. With the same sowing method, the highest plant height was in T1 for Hengguan-35, and in T2 for Han-6172. The spike length and spikelet number of the two wheat varieties reached the optimal value the nitrogen topdressing stage due to the different sowing method was different. In all the four nitrogen topdressing treatments, the flag leaf SPAD values and net photosynthetic rates of the tridimensional uniform sowing were greater than those of the drill sowing, and the net photosynthetic rate of flag leaf of nitrogen topdressing in T2 and T3 stages was significantly higher than that of nitrogen topdressing in T1 stage at 7th day and 21th day after anthesis. The SPAD values of flag leaves between the two wheat varieties were significantly different during the whole grain filling period, while the net photosynthetic rate of flag leaves was significantly different from the bloom day to the 7th day after flowering.【Conclusions】Using tridimensional uniform sowing method, the properery nitrogen topdressing time is at the 10th day since jointing stage, which is beneficial to nutritional equilibrium in single plant, developing root system, forming superior tiller population, improving the number of panicles per unit area, and increasing yield finally.