Study on the Mechanism of Slow-Release Fertilizer and Nitrogen Fertilizer on the Senescence Characteristics of Quinoa Leaves

Abstract

The objective of this study was to investigate how nitrogen and slow-release fertilizers affect the traits of leaf senescence and quinoa production in order to explore the optimal slow-release fertilizer and nitrogen fertilizer ratios suitable for quinoa production, as well as to provide theoretical references for the planting of quinoa fertilization methods and fertilizer amount. In this experiment, the main local strain Quinoa 77 was selected as the experimental material, and six treatments were set up: CK: no nitrogen fertilizer; T1: 100% urea (N); T2: 100% slow-release fertilizer (C); T3: 5:5 (C5N5); T4: 3:7 (C3N7); and T5: 7:3 (C7N3). This was done in order to investigate how various treatments affect the activities of catalase (CAT), peroxidase (POD), and superoxide dismutase (SOD); malondialdehyde (MDA) content; and yield of quinoa leaves. The findings revealed the following: (1) As the reproductive period progressed, the activities of CAT, POD, and SOD in quinoa leaves treated differently showed a tendency to increase and subsequently decrease, and they reached the peak value at the early stage of filling. The activity of CAT, POD, and SOD in the T3 treatment was the highest, and the average activities were 3148.74 U·g−1, 2197.84 U·g−1, and 118.51 U·g−1, respectively, which increased by 78.90%, 101.99%, and 108.14%, respectively, compared with CK. The content of MDA continued to increase with the progress of fertility. The average T3 treatment was 36.41 nmol·g−1, which was 46.87% lower than that of CK. (2) Out of all the treatments, T3 had the highest yield with an average of 3829.43 kg·hm−2, T5 the second with an average of 3313.52 kg·hm−2, and T4 the third with 2847.47 kg·hm−2, which increased yields by 96.18%, 69.75%, and 45.87%, respectively, compared with CK. (3) Yield was highly significantly and positively correlated with thousand kernel weight; number of grains per spike per plant; and the early filling stages of CAT, POD, and SOD sports, and it had a negative, extremely significant correlation with MDA content. Comprehensive analysis showed that slow-release fertilizer and nitrogen fertilizer can improve the antioxidant enzyme activity of quinoa leaves, inhibit MDA content, improve the physiological characteristics of quinoa, and delay the purpose of leaf senescence, with a better effect of yield and income, of which the T3 treatment had the high-quality impact of increasing yields and was a more scientific and reasonable fertilization method.