Abstract
Aiming to identify quantitative descriptors directly or indirectly related to grain yield and to verify whether this relationship depends of the growth habit of soybean ( Glycine max (L.) Merrill), an experiment was conducted at Universidade Estadual de Mato Grosso do Sul –Aquidauana Unit, in a soil classified as Ultisol sandy loam texture. The experimental design was randomized block with four replications. The treatments consisted of six soybean genotypes, being three determinate growth habit and three indeterminate. The following descriptors were evaluated: plant height (PH), first pod insertion height (PIH), number of ramifications per plant (NR), number of pods (NP), mass of hundred grains (MHG) and grains yield (YIE). The data of each parameter of genotypes with determinate and indeterminate growth habit for each genetic class were compared by t-test at 5% probability. The results obtained showed that genotypes with indeterminate growth habit are more productive compared to those who have determinate growth habit. It is recommended simultaneous selection of the descriptors NP and NR for genotypes with determinate growth habit and PH, NP and NR for genotypes with indeterminate growth.
Highlights
Among the major oilseeds cultivated in the world, the soybean (Glycine max (L.) Merrill) stands out with production of 253 million tons of grains (2012), with Brazil accountable for 25% of the total, characterizing it as the second largest producer of this crop (FAO, 2013)
The experiment was installed in the experimental area of the Universidade Estadual de Mato Grosso do Sul – Aquidauana Unit (UEMS/UUA), in Aquidauana (MS), located in the Brazilian Savanna, comprising the coordinates 20o27'S and 55o40'W and with an average elevation of 170 m
The treatments consisted of six soybean genotypes of determinate (BRS 245, BRS 255 and MSOY 7908) and indeterminate (BMX Potência, SYN 3358 and ND 5909) growth habit
Summary
Among the major oilseeds cultivated in the world, the soybean (Glycine max (L.) Merrill) stands out with production of 253 million tons of grains (2012), with Brazil accountable for 25% of the total, characterizing it as the second largest producer of this crop (FAO, 2013). The average increase of 36 kg ha-1 year-1 on productivity between 1976/77 to 2012/13 was provided mainly by genetic breeding and expansion in the area under cultivation, that this crop totaled about 28 million hectares, with an average yield of 2.9 t ha-1 (CONAB, 2013). Increases have occurred each year, genotypes with higher grain yield will be increasingly difficult to obtain, requiring more efforts of the soybean breeding programs. According to Pandini et al (2002) knowledge of direct and indirect correlations on a particular production component, especially grain yield, allow the breeder to use this additional information to rule out or to promote more accurately interest genotypes. Pípolo et al (2005) reported that the correlation between characters allows indirect selection of a quantitative character, with hard to gain selection, by selecting from another character to it directly correlated of greater genetic gain or easy visual selection
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