Search

The objectives of this study were to select maize genitors and determine the selection strategy for obtaining high quality silage maize hybrids. An experiment was conducted involving 45 hybrids obtained using a diallel scheme among commercial hybrids and four controls, in a triple lattice 7 x 7 design. The general combining ability (GCA) and specific combining ability (SCA) were significant for dry matter yield (DMY) and crude protein (CP), indicating additive and non-additive gene effects in genetic control. Only GCA was significant for plant height (PH), green matter yield (GMY) and hemicelluloses (HEM), which indicates a greater importance of additive than non-additive genetic effects in genetic control. The GCA and SCA of neutral detergent fiber (NDF) and acid detergent fiber (ADF) did not differ significantly between the hybrids, but there was a variance of 33% to 49% for NDF and 15 to 24% for ADF. The cultivars P30F90 and SHS4070 were the most recommended for increasing PH, GMY and DMY, while 2B619 and DKB466 were recommended to increase CP, and BRS3003 and AG1051 to reduce HEM. The hybrid combinations XB8028 x DKB 466, Valent x CD307, Valent x DKB466, SHS4070 x AG1051, BRS3003 x 2B619 and 2B619 x AG1051 are promising for maize silage production, because of their associated productive and qualitative traits.

A study was carried out in order to estimate the adaptability and stability of thepopcorn cultivars submitted to different environmental conditions. The simulated environments were the different sowing times in September, October, November and December, under theedaphoclimatic conditions of the Zona da Mata region, Minas Gerais, Brazil. So, eight assayswere installed at the Coimbra Experimental Station pertaining to the Universidade Federal deViçosa, during the agricultural years 1998/1999 and 1999/2000. The treatments consisted ofthe cultivars IAC 112, RS 20, and Zélia, and the Beija-flor, Branco, CMS 42, CMS 43,Rosa-claro, and Viçosa populations. The randomized block experimental design was usedwith four replicates. The plots consisted of four 4m-length rows. The spacing among rowswere 0.9 m, whereas the final stand was 45,000 plants ha-1. The adaptability and stability of thekernel productivity (kg ha-1) and the popping expansion capacity of the popcorn cultivars wereobtained by methods based on linear regression and non parametric. The general average ofthe kernel productivity was 2740 kg ha-1, while the most productive cultivars were CMS 43(3430 kg ha-1), CMS 42 (3045 kg ha-1) and IAC 112 (3045 kg ha-1). The general average ofthe popping expansion capacity was 17.5, and the cultivars showing the highest averages wereIAC 112 with 24, RS 20 with 22 and Zélia with 24. For productivity, the cultivars with morestability were CMS 43, CMS 42, IAC 112 and, Rosa-claro. For popping expansion capacity,the cultivars with more stability were Zélia, IAC 112, RS 20 and, Beija-flor. The cv. IAC 112showed stability to productivity and popping expansion capacity. The following conclusionswere drawn: the cultivars differed for adaptability and stability of the kernel productivity andthe popping expansion capacity as well; the adaptability and stability of the kernel productivityand the popping expansion capacity showed no concordance to each cultivar; the poppingexpansion capacity was more sensitive to unfavorable alterations in the environment than kernelproductivity; and IAC 112 exhibited the best association between the kernel productivity andpopping expansion capacity.