Sugarcane Breeding Institute, Coimbatore, India Effect of Different Levels of Drought during the Formative Phase on Growth Parameters and its Relationship with Dry Matter Accumulation in Sugarcane

A field experiment was conducted at Coimbatore (11 °N, 77° E), India during the 1996 and 1997 crop seasons, using four commercial sugarcane varieties (Co 8021, Co 419, Co 8208 and Co 6304), to study the effect of three levels of drought (severe, moderate and control) during the formative phase (60-150 days after planting) on growth determinants and their relationship with dry matter accumulation. The reduction in dry matter content was 60.8, 52.4 and 25.9 % in severe drought and 46.3, 36.3 and 15.1 % in moderate drought at the ends of the formative, grand growth and maturity phases, respectively. High net assimilation rate, optimum leaf area index, high crop growth rate and an early shift in dry matter allocation to the stem were found to be desirable for higher biomass production, especially under water-limited drought conditions. Measurement of growth parameters such as net assimilation rate, relative growth rate, leaf area index and leaf area duration under drought and crop growth rate and stalk elongation rate under normal irrigated conditions, particularly during the formative phase, might help to predict total dry matter at harvest. Leaf area ratio was not found to correlate with total dry matter at harvest in either drought or normal irrigated conditions.