Growth regulator and maize response to the increase in plant density

Abstract: The objective of this work was to evaluate the effect of application of the growth regulator Trinexapac-ethyl on maize response to the increase in plant density at two sowing dates. A field experiment was carried out in the municipality of Lages, state of Santa Catarina, Brazil, during the 2014/2015 and 2015/2016 growing seasons. Two sowing dates (10/15 - preferential, and 12/5 - late), four plant densities (5, 7, 9, and 11 plants m-2), with and without Trinexapac-ethyl application, were tested. The growth regulator was sprayed at a rate of 150 g a.i. ha-1, when hybrid P30F53YH was at the V5 and V10 growth stages. The spraying of Trinexapac-ethyl decreased the stem length above the ear insertion node at both growing seasons. Grain yield ranged from 11,422 to 14,805 kg ha-1, and increased in a quadratic way with the increment in plant density. The highest yields were reached when maize was sown in October. The spraying of Trinexapac-ethyl did not affect grain yield, but decreased the 1,000 kernels mass at both sowing dates. The use of Trinexapac-ethyl does not enhance grain yield of maize hybrid P30F53YH at crowded stands in response to the densification, regardless of sowing time.

摘要：本研究旨在评估生长调节剂抗倒酯（Trinexapac-ethyl）对玉米在两个播期下随种植密度增加的响应效果。试验于2014/2015和2015/2016生育季在巴西圣卡塔琳娜州拉赫斯市开展田间试验。供试处理包括2个播期（10月15日——适宜播期，以及12月5日——晚播）、4个种植密度（5、7、9、11株·m⁻²），以及施加与不施加抗倒酯两个水平。当杂交玉米品种P30F53YH处于V5和V10生育期时，以150克有效成分·公顷⁻¹的用量喷施抗倒酯。喷施抗倒酯可降低两个生育季玉米穗位节以上的茎秆长度。籽粒产量范围为11422~14805千克·公顷⁻¹，且随种植密度增加呈二次曲线变化趋势。10月播种的玉米可获得最高籽粒产量。喷施抗倒酯对籽粒产量无显著影响，但可降低两个播期下的千粒重。无论播期如何，在密植条件下施用抗倒酯均无法提升杂交玉米品种P30F53YH的籽粒产量。