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| Author(s): |
José Baldin Pinheiro
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | Piracicaba. |
| Institution: | Universidade de São Paulo (USP). Escola Superior de Agricultura Luiz de Queiroz (ESALA/BC) |
| Defense date: | 1998-08-21 |
| Advisor: | Natal Antonio Vello |
| Abstract | |
This research work is a part of to the soybean breeding program of the Department of Genetics at ESALQ/USP, and its objective was to verify the potential of soybean lines under out of season cultivation, besides joining high yield and insect resistance-favoring alleles. Experimental material envolved different populations obtained from partial diallel crosses between insect resistant and susceptible cultivars. As resistant parents, the cultivars Crockett, Lamar, IAC-100 and the experimental line D72-9601-1 were employed. As susceptible, but highly yielding and adapted parents the cultivars BR-6 (Nova Bragg), IAS-5, Davis and OCEPAR-4 (Iguaçu) were employed. The progenies F4, F5, F6 e F7 from different types of population were evaluated to the following characters: days to maturity, plant height at maturity, agronomic value and grain yield. The experiments were carried out at Anhembi Experimental Station and the experimental field at the Department of Genetics, both belonging to ESALQ/USP. The experimental designs were augmented blocks (progenies F3 and F6) and randomized complete blocks with replicates stratified in experimental sets with common controls (progeny F7); statistical-genetic analysis were carried out for each experiment and comprised progeny analysis (with media and standard deviation), genetic gain, average combining ability, phenotypic correlation among characters and generation association. Data interpretation led to the following conclusions: (a) higher number of progenies were selected from crossing envolving the parent IAC-100, these progenies showed superior performance to all evaluated characters for the different types of populations and inbreeding generations; (b) concerning to average combining ability were obtained with IAC-100, Davis and OCEPAR-4 as parent; (c) among the evaluated crosses, those with higher yields were: IAS-5 x IAC-100; Davis x IAC-100 and OCEPAR-4 x IAC-100; (d) some of the evaluated crosses showed elevated variability, that makes feasible to obtain further gains from line selection within these crosses; (e) agronomic value, although being a subjective character, is useful in yield evaluation for soybean genotypes; (f) the high correlation between the number of days to maturity and grain yield is a difficulty to obtain early and high-yielding genotypes; (g) sucker insects populations resistant showed progenies with higher agronomic value and insect resistance; (h) higher genetic gain was observed when the selection was practised ind the same environment of the cultivation. (AU) | |