Breeding investigations for development of specialty green maize hybrids.

Abstract

Green maize (Zea mays L.) provides food security and cash income to rural households in Sub-Saharan Africa (SSA). However, research on green maize varieties is scarcely reported in the literature. Consequently there is no information on suitable genetic materials (germplasm) for green maize production. Additionally there is no data regarding quality attributes of suitable hybrids, which impacts on variety development and management. Breeding investigations were therefore conducted to investigate farmers’ preferences for hybrids and attributes of green maize hybrids in KwaZulu-Natal, in South Africa, and to determine combining ability for green maize traits of experimental inbred lines that were derived from an experimental population. The study also investigated the relationships between green maize traits and some desired agronomic traits; and also sought to identify specific inbred combinations (hybrids) with potential for green maize production. A case study was conducted at Mjindi (MJD) and Ndumo (NDO) Irrigation Schemes in KwaZulu - Natal South Africa, to determine the attributes of the “ideal” hybrid, production constraints, production trends and enterprise viability. Prior to a formal survey some focus group discussions were conducted, then 64 green maize growers were interviewed using a formal questionnaire. The study indicated that the most desired consumer traits were a combination of sweet taste, long shelf life and large ears. The required attributes of the model hybrids were high grain yield potential, high selling ability, flint grain texture, white grain color, medium ear placement, thick and long ears, short maturity period, medium plant height, long shelf life and nonpopping during roasting. This study also showed that the enterprise was viable with average gross margin of about R10,000 per ha which makes it attractive to both small and large-scale commercial farmers with implications for rural development in the second economy. Thus there is a great business potential, but lack of suitable and special hybrids appears to be the major production constraint which should be addressed by research and development. A total of 100 advanced maize inbred lines were crossed in a line x tester mating scheme to generate 200 experimental hybrids. The hybrids with sufficient seed were evaluated for green maize and agronomic traits at three sites in KwaZulu-Natal. Large genotype x environment interaction effects were observed which was reflected by the different ranking of hybrids at each site resulting in selection of different sets of top 15 hybrids with potential for production in each environment. Only a few hybrids exhibited high performance consistently in at least two mega environments. The results showed that hybrids were highly significantly different for the green maize traits such as ear yield, ear length, single ear weight and marketability indices, and also for the agronomic traits. The difference among hybrids for marketing ability indices was attributed to the testers main effects and specific combining ability (SCA) effects. Differences between the general combining ability (GCA) of the lines and testers, and SCA effects were significant for the green maize traits. These findings suggested that the traits are governed by both additive and non-additive gene effects, respectively. Additionally observation of continuous and normal distribution of hybrids for the traits indicated that quantitative minor genes were involved and therefore the base population can be improved by selection for large ears, superior marketability index, and high single ear yield. The observed top performing hybrids were recommended for further testing at many sites. Results confirmed that the current dominant variety is not adapted to summer production conditions in the Mjindi and Ndumo areas which present opportunities for breeding programmes. Future studies should therefore aim to improve both the genetics and production economics of specialty green maize hybrids to further enhance profitability of the enterprise with positive implication for the rural economy in KwaZulu-Natal.