Abstract:

In this paper, the effects of different foliar fertilizer on photosynthesis, yield composition and quality of dryland wheat were studied to provide reference for high quality and efficient wheat cultivation. A field experiment was carried out in Songming, Yunnan Province in 2022, using the newly approved wheat varieties ‘Yunmai 80’ and ‘Yunmai 83’ as the research materials. Five foliar fertilizer treatments (potassium dihydrogen phosphate, brassinolide, sodium nitrate, yield-increasing agent and their mixture) and water control (three replicates) were set up, spraying at the early heading stage according to the instructions. The results showed that the net photosynthetic rate of ‘Yunmai 80’ was higher than that of ‘Yunmai 83’ under different foliar fertilizer treatments, and the difference of net photosynthetic rate between the two varieties was significant to extremely significant. The highest net photosynthetic rate was observed in KH₂PO₄ treatment, while the lowest was in auxin treatment. The chlorophyll content of ‘Yunmai 83’ was slightly higher than that of ‘Yunmai 80’, and the overall chlorophyll content decreased under the treatment of foliar fertilizer. Without considering the variety factor, foliar fertilizer spraying significantly affected the number of fertile spikelets, degenerate spikelets and effective spikelet, and had little effect on the number of grains per spike and yield. However, all foliar fertilizers increased wheat yield. KH₂PO₄, brassinolactone, sodium complex nitrate and augmentol increased the yield by 10.02%, 9.56%, 9.35% and 15.11% when applied individually. In contrast, foliar fertilizer KH₂PO₄ + brassinolactone + sodium nitrate + augmentol mixed spraying led to a yield reduction of 6.74%. For ‘Yunmai 80’, the yield increases were 19.01%, 10.77%, 9.66% and 23.59% for the individual foliar fertilizers, with a 1.98% increase for the mixture. For ‘Yunmai 83’, the yield increases were 1.40%, 8.40%, 9.06% and 6.93% for the individual foliar fertilizers, with a 15.10% yield reduction for the mixture. Foliar spraying generally reduced the protein content and increased the hardness index. However, mixed spraying increased the protein content and decreased the hardness index. The effects on water absorption, stable time, wet gluten content and sedimentation value varied due to differences between varieties, with both positive and negative effects observed for foliar fertilizers. In summary, spraying single foliar fertilizer at heading stage can promote wheat growth and development, increase yield and improve quality indicators by enhancing photosynthesis. In this study, the comprehensive effects of several common foliar fertilizers on Yunnan dryland wheat were systematically compared for the first time. The results emphasized that the appropriate foliar fertilizer should be selected according to the variety characteristics and avoid blind mixing. This study provides an important theoretical and practical basis for the precise foliar fertilization management of dryland wheat in Yunnan under winter and spring drought conditions, which is helpful to improve the drought resistance, yield and quality of regional wheat production.

Key words: wheat, foliar fertilizer, photosynthesis, yield, quality