Morpho-physiological responses of maize hybrids as a function prohexadione calcium doses applied in the vegetative phase

João F. C. C. Junior, Clovis A. Souza, Magaiver G. Pinheiro, Elijanara R. Silva and Ana L. Pinto da Silva

Abstract: Plant growth regulator prohexadione use in maize cultivation is recent, but conflicting results have been obtained on development of its vegetative structures. The aim of this study was to assess the effects of prohexadione applied in the vegetative phase, on the response of the morphophysiological parameters of maize. The pot experiments were conducted in greenhouse, in the 2017/2018 and 2018/2019 seasons. The randomized block design was arranged in a 2x7 factorial scheme with six repetitions. The main factor was growing seasons 2017/2018 and 2018/2019, and the sub factor were the growth regulator prohexadione doses: 0; 50; 100; 150; 200; 250 and 300 g ai (active ingredient) ha-1, applied on plants in V7 stage. The hybrids AS1757VTPRO3 and AG9025VTPRO3 were tested, and each hybrid consisted of an independent experiment. The application of prohexadione was an effective strategy to restricte the longitudinal growth of the plants of both hybrids. In hybrid AS1757VTPRO3, plant height was restricted up to 46% and 47%, in the 2017/2018 and 2018/2019 growing season, respectively. The reduced biological yield and kernel row number per ear in the hybrid AS1757VTPRO3 and increased the NDVI and SPAD chlorophyll index. In hybrid AG9025VTPRO3 there was a restriction on plant height growth of 53% and 57% in the 2017/2018 and 2018/2019 growing season, respectively. But the prohexadione allowed the linear increase of the leaf area in the hybrid AG9025VTPRO3. The prohexadione application leads to a decreased plants and ear insertion heights, tassel and peduncle length in a manner dependent of growing season, dose and hybrid.

Keywords: gibberellins inhibitors; plant growth regulator; Zea mays L.

Date published: 2021-02-25