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Maize (Zea mays L.) yields in Sri Lanka have been below its potential yield mainly due to biotic and abiotic stresses. This situation is likely to be aggravated in a changing climate in the future. This study was conducted under field conditions to determine the response of maize to temperature and different soil management practices during Maha season 2012/2013 at five locations (Rahangala, Peradeniya, Kundasale, Mahailluppallama and Kilinochchi) in Sri Lanka representing an environmental gradient together with three soil management systems (SMS) in a Randomized Complete Block Design (T1 – standard management; T2 - standard management plus mulching; T3 mulching + 75% of N supplied by inorganic fertilizer + 25% N from organic manure). The rate of progress to maturity showed a significant positive linear relationship with the mean location temperature (MLT), thus shortening the crop duration with increasing temperature. Leaf area index (LAI) and total dry weight (TDW) at 50% flowering in all SMSs showed significant second-order polynomial relationships with MLT. The optimum temperatures for the maximum LAI and TDW were 23.0 and 22.8 0C, respectively. Total dry weight of T3 and T2 were 22% and 9% greater than T1 thus, showing the beneficial effects of mulching and adding organic manure. The grain yield of maize also showed a significant second-order polynomial relationship with MLT with an optimum temperature of 22.5 oC. It is notable that all major maize growing regions of Sri Lanka (i.e. dry and intermediate zones) have temperatures, which are above the respective optima for growth and yield of maize. Furthermore, the fitted polynomial relationships showed that the rates of decline in maize yield (i.e. 489 kg ha-1 oC-1), LAI (0.98 oC-1)and (1390 kg ha-1oC-1 with each 1 oC increase in the supra-optimal range of temperatures were greater than the corresponding rates of increase in the suboptimal range (15 kg ha-1 oC-1, 0.33 oC-1 and 330 kg ha-1oC-1 for yield, TDW and LAI, respectively). Therefore, increased temperature due to future climate change will have significant negative impacts on maize yields in Sri Lanka, unless more heat-tolerant varieties are bred and introduced.Tropical Agricultural Research Vol. 25 (3): 327-344 (2014) |
