Temperature and seasonal effects on canopy development and light interception of sugarcane

Abstract

Abstract Canopy development in sugarcane is slow compared to annual crops and sucrose production per annum can be substantially reduced if harvest age is limited by pests or other factors. A better understanding of factors affecting canopy development may allow farmers to develop more efficient planting and harvest schedules as well providing a basis for cultivar improvement. Two Natal cultivars (NCo376 and N12) were grown without irrigation on a sandy clay soil and were ratooned at least once on eight occasions at 2-month intervals. The base temperature for leaf appearance was determined as 10°C by regressing leaf numbers against thermal time and by comparing leaf extension rate and air temperature. A base temperature of 16°C was established for tiller appearance. Peak stalk density occurred approximately 500°C day after ratooning. Leaf senescence was correlated with leaf appearance and with soil water content. Tiller senescence occurred after the canopy closed beyond 70% interception of photosynthetically active radiation (PAR). Final leaf area increased linearly up to about 400 and 420 cm2 for leaf 16 of NCo376 and N12, respectively. Area did not increase much after leaf 16 and was reduced when soil water content was low. The phyllochron interval was 109 and 118°C day up to leaf 14 and was 169 and 200°C day thereafter for NCo376 and N12, respectively. Measurements indicated that annual radiation was intercepted most efficiently by crops ratooned in February and least efficiently by crops ratooned in April.