Zinc fertilization in cowpea cultivars

ABSTRACT Zinc (Zn) is an essential micronutrient for plants, due to its role as a functional, structural, or regulatory cofactor in a large number of enzymes. The element is necessary for the synthesis of tryptophan, which is a precursor of indoleacetic acid. The aim of this study was to evaluate the behavior of two cowpea cultivars fertilized with four doses of Zn (0.0, 2.0, 4.0, and 6.0 kg of Zn ha-1) regarding dry grain yield (PGS), in addition to quantifying leaf and grain Zn content and grain crude protein. The experiment was conducted in the town of Brejo, in the state of Maranhão, Brazil. A 4 x 2 factorial scheme was used with four replications. Response functions were adjusted by calculating the Zn doses which provided a maximum technical efficiency for each genotype. The tested cultivars of cowpea showed no great difference regarding Zn demand applied to the soil, ranging from 3.2 to 3.4 kg of Zn ha-1 for BRS Tumucumaque and BRS Guariba, respectively. Concerning Zn use efficiency, BRS Guariba was more responsive than was BRS Tumucumaque, i.e. the same dose of Zn produced 70 kg grain and 2.1 kg crude protein per hectare.

摘要 锌（Zinc, Zn）是植物必需的微量营养元素，可作为多种酶的功能、结构或调节辅因子发挥作用。该元素是色氨酸合成的必需物质，而色氨酸是吲哚乙酸的前体。本研究旨在评估两个豇豆品种在施加四种锌施用量（0.0、2.0、4.0和6.0 kg Zn·ha⁻¹）下的籽粒干产量（PGS）表现，并同时量化叶片、籽粒的锌含量以及籽粒粗蛋白含量。试验于巴西马拉尼昂州Brejo镇开展，采用4×2因子设计，设置4次重复。通过计算各基因型达到最大技术效率所需的锌施用量，拟合得到响应函数。供试的两个豇豆品种对土壤施锌的需求量差异不大，BRS Tumucumaque和BRS Guariba的需锌量分别为3.2 kg·ha⁻¹和3.4 kg·ha⁻¹。在锌利用效率方面，BRS Guariba的响应效果优于BRS Tumucumaque，即相同施锌量下，每公顷可产出70 kg籽粒及2.1 kg粗蛋白。