Abstract
Stalk lodging in Huang-Huai-Hai summer maize is a serious problem that reduces maize yields and precludes the use of mechanical grain harvesting equipment. In order to determine the effect of nitrogen management on the lodging resistance of maize stalk, three nitrogen application rates of 150, 250, and 350 kg ha−1 (denoted as N150, N250, and N350), and different nitrogen application periods (sowing, 6-leaf, 12-leaf, silking) were set. Plant morphology, stalk mechanical strength, total carbohydrate, nitrogen content, and yield were measured in the different treatments. The results showed that as the nitrogen application rate increased and nitrogen application was postponed, the stalk breaking force, plant height, ear height, center of gravity height, stalk basal internode diameter, rind penetration strength, content of carbohydrate, and total N of maize stalk also increased. The stalk lodging resistance was improved by the increased nitrogen application rate and postponed nitrogen application by increasing the stalk material accumulation and mechanical strength. The nitrogen application rates had no significant effect on grain yield. Under N250 and N350, the treatments with no base fertilizer significantly decreased the kernel number per ear, reflected in some in grain yield. In summary, under the conditions of integrated water and fertilizer drip irrigation and fractional nitrogen fertilizer applications, increased nitrogen fertilizer input can stimulate the growth of high-quality maize populations, significantly improve stalk lodging resistance in the early growth stage, delay stalk senescence, improve stalk strength and influence stalk composition in later growth stages. Based on the summer maize grain yield and stalk lodging resistance, under N250 treatment, a base fertilizer combined with topdressing at the 12-leaf and silking stages was beneficial to the growth of summer maize.
Highlights
As maize is the largest food crop in China and the world, the stable yield of maize is highly relevant to national food security [1]
Nitrogen fertilizer can increase the photosynthetic capacity of maize plants in the middle and late growth stages and prolong the functional period of the middle and lower leaves, which significantly contributes to increased yields of maize [8]
This study explores the effects of nitrogen fertilizer management on lodging resistance and maize yields regarding plant mechanical characteristics, agronomic characteristics, stalk carbohydrate accumulation characteristics, yield composition, dry matter, and leaf area index across set levels postponing nitrogen application
Summary
As maize is the largest food crop in China and the world, the stable yield of maize is highly relevant to national food security [1]. Nitrogen fertilizer can increase the photosynthetic capacity of maize plants in the middle and late growth stages and prolong the functional period of the middle and lower leaves, which significantly contributes to increased yields of maize [8]. The time between the six-leaf and silking stages of summer maize is crucial for absorbing nitrogen, phosphorus, and potassium; during this period the nutrient absorption rate is rapid and nutrient accumulation is high [9]. The period between the six-leaf and silking stages is a prime time for the fertilization of super-high-yield summer maize. Research shows that with nitrogen application rates of 210 and 350 kg ha−1, postponed nitrogen fertilizer application can promote nitrogen absorption and accumulation in the later growth stages of maize, and significantly improve maize yields and nitrogen use efficiency [10,11]. The rational application of nitrogen fertilizer based on its effect on crop productivity has become a primary focus of agricultural production research [14]
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