[Effects of straw returning and nitrogen application rate on photosynthesis and fluorescence characteristics in flag leaves and grain yield of wheat in dryland].

内容摘要

We examined the effects of straw returning and nitrogen application rates on the photosynthetic and fluorescence characteristics in flag leaves and grain yield of wheat (Luohan 22) in drylands, with an experiment following split-plot design. The main plot treatments were straw returning, namely S0(no straw returning) and S1(total straw returning with the amount of 9000 kg·hm-2). The subplot treatments were five nitrogen application rates of 0, 120, 180, 240, and 300 kg·hm-2, represented by N0, N1, N2, N3, and N4 respectively. We measured the photosynthetic and chlorophyll fluorescence parameters in flag leaves at 0, 7, 14, 21, and 28 days after flowering, as well as the final yield and yield components. The results showed that net photosynthetic rate, transpiration rate, stomatal conductance, and photochemical quenching of all treatments showed a decreasing trend with growth period progressing. The maximum photochemical quantum yield and electron transport rate first increased and then decreased with the growth process, peaking at 7 and 14 days after flowering, respectively. The non-photochemical quenching coefficient showed an increasing trend as the growth period progressing. At each nitrogen application level, net photosynthetic rate, transpiration rate, stomatal conductance, photochemical quenching, maximum photochemical quantum yield, and electron transport rate at each measurement period were all higher in S1 than in S0. Under the same straw returning treatment, these parameters first increased and then decreased with increasing nitrogen application rate, with the highest value in N3. Compared with S0N3, the indicators of S1N3 increased by 4.3%, 6.1%, 2.6%, 5.9%, 3.9% and 11.0%, respectively. The non-photochemical quenching coefficient was higher in S0 than in S1 at the same nitrogen application rate. Under the same straw returning conditions, it first decreased and then increased with increasing nitrogen application rates, with the highest value in N0. The non-photochemical quenching coefficient in S1N3 was 4.1% lower than that in S0N3. The effective panicle numbers, grains per panicle, 1000-grain weight, and yield of wheat were all higher in S1 than in S0 under the same nitrogen application rate. Under the same straw returning treatment, these parameters first increased and then decreased with increasing nitrogen application rates. Among all the treatments, S1N3 gained the highest spike numbers, grains per panicle, 1000-grain weight, and yield, which was 2.1%, 2.7%, 3.9%, and 5.2% higher than that under S0N3, respectively. Similarly, the economic benefit and cost-benefit ratio reached their highest in S1N3, at 12629 yuan·hm-2 and 198.1% respectively, both being 8.0% higher than S0N3. Therefore, straw returning combined with nitrogen application rate at 240 kg·hm-2 is a suitable cultivation practice for dryland wheat in the western Henan Province and regions with the same conditions. 为明确秸秆还田和施氮量对旱地小麦旗叶光合、荧光特性和产量的影响,以洛旱22为试验材料,采用裂区试验设计,主区为秸秆还田处理,分别为S0(不还田)和S1(全量还田,还田量9000 kg·hm-2);裂区为5个施氮量处理,分别为N0 (0 kg·hm-2)、N1 (120 kg·hm-2)、N2 (180 kg·hm-2)、N3 (240 kg·hm-2)和N4 (300 kg·hm-2),测定了花后0、7、14、21和28 d的光合特性、叶绿素荧光参数和产量及其构成因素。结果表明: 随着生育期的推进,各处理的净光合速率、蒸腾速率、气孔导度和光化学猝灭系数均呈下降趋势;最大光化学量子产量和电子传递速率随生育进程呈先上升后下降趋势,分别在花后7和14 d达到最大值;非光化学猝灭系数随生育期推进呈上升趋势。各测定时期的净光合速率、蒸腾速率、气孔导度、光化学猝灭系数、最大光化学量子产量和电子传递速率在同一施氮水平下均表现为S1高于S0,在同一秸秆还田处理下均随施氮水平的提高呈先升后降趋势,总体表现为N3处理最高,S1N3比S0N3分别提高4.3%、6.1%、2.6%、5.9%、3.9%和11.0%。非光化学猝灭系数在同一施氮水平下表现为S0高于S1,在同一秸秆还田处理下均随施氮水平的提高呈先降后升趋势,总体表现为N0处理最高,S1N3比S0N3降低了4.1%。小麦有效穗数、穗粒数、千粒重和产量在同一施氮水平下均表现为S1高于S0,同一秸秆还田处理下均随施氮量的提高呈先升后降趋势。穗数、穗粒数、千粒重和产量均以S1N3最大,与S0N3相比,分别提高2.1%、2.7%、3.9%和5.2%。经济效益和成本收益率在S1N3达到最高,分别为12629元·hm-2和198.1%,较S0N3均提高8.0%。综上,秸秆全量还田配施240 kg·hm-2氮肥是豫西旱地及类似生态区小麦适宜栽培措施。.