Abstract
The stay-green leaf phenotype is typically associated with increased yields and improved stress resistance in maize breeding, due to higher nitrogen (N) nutrient levels that prolong greenness. The application of N fertilizer can regulate the N status of plants, and furthermore, impact the photosynthetic rates of leaves at the productive stage; however, N deficiencies and N excesses will reduce maize yields. Consequently, it is necessary to develop N fertilizer management strategies for different types of stay-green maize. For this study, the senescent cultivar Lianchuang 808 (LC808), moderate-stay-green cultivar Zhengdan 958 (ZD958), and over stay-green cultivar Denghai 685 (DH685) were selected as experimental models. Our results revealed that yields of ZD958 were slightly higher than DH685 and notably improved over than LC808. Compared with a non-stay-green cultivar LC808, ZD958 and DH685 still maintained higher chlorophyll contents and cell activities following the silking stage, while efficiently slowing the senescence rate. The supply of N fertilizer significantly prolonged leaf greenness and delayed senescence for ZD958 and DH685; however, the effect was not obvious for LC808. The stem remobilization efficiency of N was higher in the moderate-stay-green cultivar ZD958, in contrast to LC808, while the transfer of leaf N was lower than LC808, which guaranteed high leaf N levels, and that sufficient N was transferred to grains in ZD958. To obtain the highest yields, the optimal N fertilizer rates were 228.1 kg hm−2 for LC0808, 180 kg hm−2 for ZD958, and 203.8 kg hm−2 for DH685. In future, the selection of stay-green type crops might serve as an important agricultural strategy to reduce the quantity of N fertilizer and increase N efficiency.
Highlights
Maize (Zea mays L.) is one of the world’s most widely cultivated crops, providing food and animal feed as well as being a source of biofuel. [1,2]
Maize grain yield has increased eight-fold with the majority of the yield being attributed to selection and hybrid breeding [5], which was due to increased maize greenness [6,7]
Stay-green crops were classified into four types based on the differences of genes in leaf senescence and expression time [28]: type A, initiation of the entire senescence syndrome may be delayed; type B, the syndrome may begin on time but proceed at a decelerated rate; type C and type D were non-functional and had no value in production
Summary
Maize (Zea mays L.) is one of the world’s most widely cultivated crops, providing food and animal feed as well as being a source of biofuel. [1,2]. In 1987, Willman (1987) initially classified maize as non-stay-green and stay-green, contingent on the degree of the greenness of its leaves. The former category is referred to as a premature senescence cultivar, which means that its leaves become less green 30 days after flowering, and basically disappear at the grain maturity stage. The latter category refers to a sustained level of green (the overall proportion of a leaf that stays green) and no obvious loss of color at the maturity stage [8]
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