Physiological characteristics at flowering of two soybean varieties UFV-1 and IAC-7, in different planting dates and its relation with seed production

Abstract

A study was made on early, normal and delayed planting dates on the physiological characteristics at flowering of two late soybean varieties, UFV-I and IAC-7 and its relation with seed production. The parameters avaluated were: planta height, number of nodes, leaf area index leaf dry weight. The field experiment was carried out at Campinas Experimental Station on an eutrophic Latosol Roxo, during the years 1979/80 and 1980/81. In the year plantings were made every twenty days starting from October 5 and in the second year every thirty days starting from September 17, the total being eight and seven in the consecutive years. Early plantings affected all physiological characteristics yielding lower values than in normal dates, for UFV-1. The values were identical for IAC-7 in early and normal planting dates. The delayed planting dates lowered drastically the values of all physiological characteristics in both varieties. All the avaluated parameters at flowering correlated with seed production in both varieties through the planting dates. It was verified that differences between the two varieties for each planting date did not como up to differences of seed production. The physiological characteristics at flowering were suitable to avaluate the seed production of each variety through the planting dates but were not suitable to compare the two varieties in the same planting date.