Abstract:

Spring maize field trials were conducted in 2022 and 2023 in the Yinhuang Irrigation District of Ningxia, respectively, using a one-way randomized block design with a total of six potassium application levels of 0, 60, 120, 180, 240 and 300kg·ha⁻¹, which were recorded as K0, K1, K2, K3, K4 and K5, respectively. To analyze the change rule of photosynthetic parameters of spring maize leaves, the interrelationship between filling characteristics and yield under different potassium fertilizer treatments, to study the effects of different potassium application rates on the photosynthetic physiological characteristics, filling characteristics and yield of spring maize under drip irrigation and water−fertilizer integration, and to clarify the optimal potassium application rate for spring maize under drip irrigation and water−fertilizer integration technology. The results showed that the photosynthetic potential (LAD) of spring maize before flowering (V6-R1) accounted for about 20% of the whole reproductive LAD, and the post-flowering (R1−R6) LAD accounted for 80% of the whole reproductive LAD, and the accumulation of spring maize substances mainly occurred after flowering. The net photosynthetic rate (Pn) of spring maize leaves all reached the maximum peak in the R1 stage, and the K3 treatment significantly increased by 18.00% compared with the K0 treatment. Maximum grain growth (W_max) reached maximum in 2022 and 2023 in K3 treatment, which was 4.83% to 11.41% and 4.82% to 6.89% higher compared to other treatments, respectively. In addition, the number of days of grain filling duration (T) and the period of active filling were both maximized (P) in the K3 treatment. With the increase of potassium application, the maize yields all showed an increasing and then decreasing trend, and the K3 treatment had the largest yield, which was 14767kg·ha⁻¹ and 14964kg·ha⁻¹ in 2022 and 2023, respectively. Pearson's correlation analysis showed that there were highly significant positive correlations between photosynthetic potential, stomatal conductance and yield, and significant correlations between net photosynthetic Pn, intercellular carbon dioxide concentration(Ci), transpiration rate(Tr), W_max and P; Principal component analysis showed that the K3 treatment had the highest overall score for maize yield optimization. It indicates that reasonable application of potash fertilizer can effectively ensure photosynthesis of spring maize, prolong the duration of grouting and maximum grouting rate, increase the amount of maize growth at the maximum filling rate, increase the maximum filling rate, promote the transformation of substances, and thus improve the yield of spring maize.

Key words: Spring maize, Potassium application, Photosynthetic potential, Photosynthetic parameters, Filling characteristics, Yield