Heat-Sum Calculation in Forecasting Maize Phenological Stages and Harvesting Date in Lagos South West, Nigeria

Maize production is of primary importance in the world, especially considering that its cultivation takes up one of the greatest ratios of land used for agricultural production.Based on analysis of rainfall pattern and thermal regime, maize phenological stages and harvesting dates has been investigated with the use of heat-sum calculation along with the seasonal rainfall forecast by NIMET in relation to maize crop production. Data were collected from Agro-meteorological Observatory of Nigerian Meteorological Agency (NIMET), Oshodi Lagos, Nigeria. Maize phenological records were collected during the period between 2005 and 2010. Also, information obtained includes phenological records for ten different period of maize crop forecast. The monthly mean values of all parameters were further averaged to obtain the annual mean. Microsoft Excel was used to show the correlation between these parameters rainfall, temperature and crop yield data between 1995 and 2010. Heat-sum calculation was employed as a forecasting guide of growing phase of maize crop and harvesting date in the study area. Graph of the yield were plotted against temperature and rainfall. Results show the length of growing-period with use of heat sum calculation and harvesting date of maize crop grown was forecasted. Results show that maize crop could be grown with the use of crop weather calendar considering life history and mean dates of important epoch of crop growth and development of maize phonological stages, sowing to germination, germination to emergence, emergence to 3rd leaf, 3rd leaf to 9th leaf, 9th leaf to tasselling, tasselling to flowering, flowering to soft dough, soft dough to hard dough, hard dough to harvesting dates with total number of 73 days. Heat units, expressed in growing days are frequently used to describe the timing of biological processes. The basic equation used was HS = [(TMAX + TMIN)/2]−TBASE, where TMAX and TMIN are daily maximum and minimum air temperature, respectively, and TBASE is the base temperature. The methods of interpreting this equation for calculating heat-sum is if the daily mean temperature is less than the base, it is set equal to the base temperature or if TMAX or TMIN < TBASE they are reset equal to TBASE. Average rainfall observed was 30mm in 10 days with duration of wet spell > 4 days. High wind exceeded 40knot. The minimum temperature recorded was 10ºC at night with maximum temperature of 400C during the day. Furthermore, result show that 10ºC is the base temperature of maize below this, the growth will be zero. 25º ─ 38ºC is the optimum temperature for best or highest yield.