Avaliação e seleção de progênies S2 de milho pipoca com base em características morfoagronômicas

Abstract

Investment in breeding programs is of importance to encouraging the Brazilian agriculture, reducing the number of imports and favoring farmers in the country. Accordingly, the production of hybrids partially inbred lines endogamy is an attractive alternative due to lower cost and acquisition time, requiring a smaller number of selfing, however decreading the value of the seeds. This work had the objective to avaluate and select S2 progenies of popcorn from morphological characteristics of the culture. The experiment was conducted in the 2014/2015 harvest, in Dourados-MS. We evaluated 23 progenies S2 of popcorn in a randomized block design with three replications, and analyzed the features female flowering (FF), male flowering (FM), plant height (AP), and insertion the first ear (AE), stem diameter (DC), lodging and culm breakage (AQ), number of ears (NE), grain yield (REND), 1000 grain weight (P1000) and seed popping ability (CE). For all source of progenies variation, it is found statistic difference significant for all characteristics, except FF and FM, indicating existence of variability among progenies. All characteristics, the progenies average were grouped, by ScottKnott test, in two grups, beyond P1000, that was grouped into three. The overall average of FF and FM was respectively 73 and 71 days. The heritability estimate was higher than 70% for REND, P1000, AP and CE, indicating that most of the phenotypic variation was due to genetic differences existing among progenies. It has been observed higher prediction in gain direct with selecting the characters height insertion the ear (AE) (10,41%), grain yield (REND) (50,02%) and number of ears (NE) (25,89%). Selection based on the EC provided low gain estimates in most characteristics, highlighting the number of ears (NE), 1000 grain weight (P1000) e REND, all related to productivity. When the response the selection indirect is negative the simultaneous improvement of two characteristics is inviable. It is noteworthy the lack of genetic correlation observed between CE and NE, and CE and REND, and the negative correlation in between CE and P1000 (-0,33). However, both the selection based on the NE as in P1000 can provide indirect gain in REND, 36,89% and 41,44%, respectively. This is reflects of high genetic correlation between the NE and the REND and P1000 and the REND, beyond the heritability coefficient above 62% for the three characteristics. Selection based on plant height (AP) provided larger prediction of indirect gain in AE (7,79%) than own direct gain (6,42%). For characteristics FF and FM was not verified positive response with the direct or indirect selection, fact confirmed due to low variability between strains for these characteristics.