Controle genético do indice de colheita no feijoeiro

Abstract

The harvest index (IC), the proportion of grain dry matter and total plant dry matter weight, is a measure of biological efficiency. This index is influenced by numerous factors, but it is expected to be higher in the cultivars more recent obtained. This study aimed to verify if IC is higher in modern cultivars, if its estimate varies with the plant cycle, the origin gene pool of the cultivar and environmental conditions. Additionally, get information about the IC genetic control, through diallel crossing, from lines with wide variations in origin and other characteristics. For this, was performed a complete diallel without considering the reciprocal, using six lines. The 21 treatments were evaluated in three harvests/generations - F2, F3 and F4 - during 2015. The experimental design was a randomized block with four replications. The plot consisted of 3 lines with 4 m. In the central line was placed a screen receptacle 1 m long aimed to collect leaves, pods and other plant parts falling before harvest. The collection of the falling plant material was made every three days, after flowering, on the receptacle bottom. The characters evaluated were: plant total dry matter, number of days to flowering, grain yield per plant (PG) and IC. The IC data and PG were subjected to analysis of variance. Using the means, proceeded the diallel analysis per generation and combined using the methodology Griffing, (1956). The IC was greater in modern cultivars and also in crop whose seeds were sown in February. For PG general combining capacity (GCG) explained most of the variation, indicating the predominance of additive effects. As for IC the heterosis was negative leading to infer that occur dominance to reduce the character expression. The parents differed in CGC for IC and PG. The most modern cultivars were among the highest CGC for both characters.