G. Suja

Short-duration cassava genotypes for crop diversification in the humid tropics: growth dynamics, biomass, yield and quality.

BACKGROUND Short-duration (6-7 months) cassava provides opportunities to smallholder farmers for effective utilisation of resources such as land, moisture and nutrients as well as diversification of enterprise and income. The variation in biomass production and partitioning, seasonal course of growth indices, yield, quality and nutrient uptake of ten short-duration/early-bulking genotypes of cassava and their impact on nutrient contents in soil in a lowland situation akin to rice fallow were examined in this study. RESULTS Triploid 2-18 gave the highest yield (38.34 t ha(-1)), followed by triploid 4-2, Sree Vijaya, Sree Jaya and Vellayani Hraswa, which were on a par (30-32 t ha(-1)). Vellayani Hraswa, Sree Vijaya and triploid 4-2 had significantly higher tuberous root dry matter content (370-380 mg g(-1)) and fairly higher starch content (270-280 mg g(-1)). All genotypes except triploid 4-2, triploid 2-18 and H-165 had low cyanogen content (29.2-43.8 microg g(-1)), well within the tolerable limit. Tuberous root dry matter and total dry matter production, crop growth rate, tuberous root bulking rate and harvest index at the last phase, number of tuberous roots, mean weight of tuberous roots and nutrient uptake showed significant positive correlations with tuberous root yield. Principal component analysis also showed a similar trend. CONCLUSION The diploids Sree Vijaya, Sree Jaya, Vellayani Hraswa and Kalpaka are ideal for cultivation in rice fallow for food use owing to their high yield, good cooking quality and low cyanogen content. The triploids are better suited for industrial use owing to their high tuberous root dry biomass production.