Climatic conditions requirements of maize germplasm for flowering in the rainforest Agro-ecology of Nigeria

The number of days from planting to flowering in maize (Zea mays L.) is of interest to maize breeders because of its importance in the selection of appropriate hybrid parents. Highly significant interaction of planting dates with varieties for flowering traits have been observed during the early and late cropping seasons in the rainforest agro-ecology of South West Nigeria. This makes the use of flowering dates as indicators of maturity unreliable. Therefore the objectives of this study were to evaluate 100 maize varieties for flowering traits and determine the climatic factors influencing the interaction of the environments with days to flowering (GxE) in the rainforest ecology of South West Nigeria. One hundred maize varieties were evaluated during the late and early cropping seasons of 2007/2008 and 2008/2009. Significant differences were observed among the varieties for flowering traits (days to 50% tasseling, anthesis and silking). There was also significant variety x season interaction mean squares. In the early season, TZEE-WSRBC5, TZEEPOPSTRCo and 97TZEE-Y-2C1 with 47-53 days to full flowering were the earliest to flower while Oba-Super II and ACR96DMR-LSR W with 64-71 days to flowering were the latest to flower. In the late seasons, 2004TZEE-WPOPSTRC4, TZEEPOPSTRCo, SINETEE-WSR and TZE-WPOPDTSTRC4F2 were the earliest to flower (42-47 days) while BUSOLA STR, TZLCOMPCO, 9021-18STR and Oba super II were the latest (61-68 days). Flowering interval was shorter in the late than the early season regardless of the maturity group with temperature as main climatic factor influencing flowering in this ecology.   Key words: Maize, germplasm, climatic condition, rainforest, agro-ecology.