Clarifying the effects of different phosphorus (P) application rates on grain weight and yield of wheat under water-saving supplementary irrigation can provide a basis for determining a reasonable amount of phosphate fertilization. Taking 'Jimai 22' as the test material in the wheat growing season of 2022-2023 and 2023-2024, we set up five P application rates of 0 (P0), 45 (P1), 90 (P2), 135 (P3) and 180 kg·hm-2(P4), with the soil relative moisture being supplemented to 70% in the 0-40 cm soil layer at the jointing and anthesis stages. We measured the chlorophyll fluorescence and senescence characteristics of flag leaves and grain filling traits in wheat. The results showed that compared with P0 and P1 treatments, maximum photochemical efficiency (Fv/Fm), actual photochemical efficiency (ΦPSⅡ), photochemical quenching coefficient (qp), superoxide dismutase (SOD) activity and soluble protein content of flag leaves were significantly increased in P2 treatment after anthesis, while the non-photochemical quenching coefficient (NPQ) and malondialdehyde (MDA) content of flag leaves were significantly decreased, and the high duration value of the relative chlorophyll content (SPAD) of flag leaves was prolonged. In the two growing seasons, P2 treatment significantly increased the active growth period (D) and actual final filling period (T) of grains, soluble sugar content, and starch accumulation compared to P0 and P1 treatments. 1000-grain weight in P2 treatment in the 2022-2023 and 2023-2024 growing seasons was increased by 11.5% and 11.9% compared to P0 treatment, and increased by 9.0% and 9.2% compared to P1 treatment, respectively. The grain yield was 30.9% and 37.9% higher respectively than that under P0 treatment, and 17.3% and 21.1% higher respectively than that under P1 treatment. When P application rate was increased to those in P3 and P4 treatments, NPQ and MDA, as well as other indices did not increase. The 1000-grain weight was significantly and positively correlated with Fv/Fm, ΦPSⅡ, qp, SOD, soluble protein content, D, T, grain soluble sugar content and starch accumulation, and negatively correlated with NPQ and MDA. In conclusion, under water-saving irrigation supplementary irrigation conditions, 90 kg·hm-2 was the optimal P application rate, which could ensure the strong photosynthetic capacity of flag leaves, prolong grain filling time, promote grain starch accumulation, increase the grain weight, yield and phosphate fertilizer agronomic efficiency.
明确节水补灌下施磷量对小麦粒重和产量的影响及其生理机制,可为确定合理的磷肥用量提供依据。本试验于2022—2023和2023—2024年小麦生长季以‘济麦22’为试验材料,设置0(P0)、45(P1)、90(P2)、135(P3)和180 kg·hm-2(P4)5个施磷量处理,各处理均于拔节期和开花期将0~40 cm土层土壤相对含水量补灌至70%,研究小麦旗叶叶绿素荧光和衰老特性及籽粒灌浆特征。结果表明: 与P0和P1处理相比,P2处理开花后旗叶最大光化学效率(Fv/Fm)、实际光化学效率(ΦPSⅡ)、光化学淬灭系数(qp)、超氧化物歧化酶(SOD)活性和可溶性蛋白含量均显著提高,非光化学淬灭系数(NPQ)和丙二醛(MDA)含量显著降低,叶绿素相对含量(SPAD)高值持续期延长;两生长季P2处理籽粒活跃生长期(D)、实际灌浆终期(T)、可溶性糖含量和淀粉积累量均比P0和P1处理显著提高。2022—2023和2023—2024年生长季P2处理的千粒重比P0处理分别提高11.5%和11.9%,比P1处理分别提高9.0%和9.2%;籽粒产量比P0处理分别提高30.9%和37.9%,比P1处理分别提高17.3%和21.1%。增加施磷量至P3、P4处理,NPQ和MDA不再增加,其他指标均未显著升高,磷肥农学效率降低。千粒重与Fv/Fm、ΦPSⅡ、qp、SOD、可溶性蛋白含量、D、T、籽粒可溶性糖含量和淀粉积累量均呈极显著正相关,与NPQ、MDA呈极显著负相关。综上,施磷量为90 kg·hm-2在本试验节水补灌条件下能保证旗叶较强光合能力和较长籽粒灌浆时间,促进籽粒淀粉积累,进而提高粒重,获得较高产量和最优磷肥农学效率。.
Keywords: chlorophyll fluorescence; grain filling; grain weight; phosphorus fertilizer application rate; senescence characteristics; wheat.