Regional and Seasonal Effects on Phenology of Mungbean ( Vigna radiate ( L.) Wilczek ) and Black Gram ( Vigna radiate ( L.) Hepper ) in Thailand

Abstract

Knowledge of how the environment affects the development and growth of a crop, and how different genotypes respond to particular environmental factors, is a prerequisite to directed plant improvement. This paper is a progress report on a collaborative study being conducted within Thailand to examine the regional and seasonal components of environmental effects on growth and development of fourteen mungbean ( Vigna radiate ( L .) Wilczek ) and six black gram ( Vigna radiate ( L .) Hepper ) genotypes. In the study, sowings of all genotypes were made at monthly intervals in five locations distributed throughut Thailand : Phitsanulok, Khon Kaen, Chainat, Kamphaengsean and Hat Yai. Plantings commenced in mid-1986 and ended in mid-1987. Phenological data from the first six months of the study are presented and discussed in terms of two key climatic factors affecting plant growth and development, daylength and temperature. Averaged over genotypes, effects of location and sowing date were large. In general, flowering occurred earlier at more southern locations and, as swoing was delayed from May to September. However there were also significant genotype interactions with planting locations and sowing dates. In general, the phonological responses observed within both mungbean and black gram were consistent with either daylength insensitivity or quantitative short-day photoperiodic response.