Effects of growth regulators on flowering and productivity of soybean (Glycine max cv. Davis)

aesalq Anais da Escola Superior de Agricultura Luiz de Queiroz An. Esc. Super. Agric. Luiz de Queiroz 0071-1276 2316-8935 Universidade de São Paulo; Escola Superior de Agricultura Piracicaba, SP, Brazil This study was conducted with the objective of determing the effects of growth regulators on flowering and productivity of soybean plant under greenhouse conditions. Applications of (2-chloroethyl) trimethylammonium chloride (CCC) 2,000 ppm, succinic acid-2,2-dimethylhydrazide (SADH) 4,000 ppm, gibberellic acid (GA) 100 ppm, indolylacetic acid (IAA) 100 ppm, and water (check treatment) were made on plants showing 4 leaves. SADH delayed the beginning of flowering. GA reduced time for maximum flowering. SADH reduced the flowering time in relation to the check treatment. Soybean plants treated with SADH produced a lower number of pods. 'Davis' soybean sprayed with GA presented an increase in dry weight of stems. Efeitos de fitoreguladores na florescência e produtividade da soja(Glycine max cv. Davis) Effects of growth regulators on flowering and productivity of soybean (Glycine max cv. Davis) Paulo R.C. Castro Departamento de Botânica, E.S.A. "Luiz de Queiroz", USP RESUMO Verificou-se em condições de casa de vegetação o efeito de fitoreguladores na florescência e produtividade da soja 'Davis'. Quando as plantas apresentavam 4 folhas definitivas, aplicou-se através de pulverização, cloreto (2-cloroetil) trimetilamonio (CCC) 2.000 ppm, ácido succínico-2,2-dimetilhidrazida (SADH) 4.000 ppm, ácido giberélico (GA) 100 ppm e ácido indolilacético (IAA) 100 ppm, além do controle. Efetuaram-se contagens diárias do número de flores e o número de vagens foi determinado semanalmente. Na colheita estabeleceram-se os parâmetros de produtividade. O delineamento experimental foi inteiramente casualizado com 6 repetições, procedendo-se a comparação de médias pelo teste Tukey ao nível de 5% de probabilidade. Observou-se que o SADH retardou o início da florescência, reduziu o período de florescimento e diminuiu o número de vagens produzidas. Aplicação de GA retardou a ocorrência da maxima florescência e aumentou o peso da matéria seca do caule da soja 'Davis'. SUMMARY This study was conducted with the objective of determing the effects of growth regulators on flowering and productivity of soybean plant under greenhouse conditions. Applications of (2-chloroethyl) trimethylammonium chloride (CCC) 2,000 ppm, succinic acid-2,2-dimethylhydrazide (SADH) 4,000 ppm, gibberellic acid (GA) 100 ppm, indolylacetic acid (IAA) 100 ppm, and water (check treatment) were made on plants showing 4 leaves. SADH delayed the beginning of flowering. GA reduced time for maximum flowering. SADH reduced the flowering time in relation to the check treatment. Soybean plants treated with SADH produced a lower number of pods. 'Davis' soybean sprayed with GA presented an increase in dry weight of stems. 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