Cassava Growth Analysis of Production during the Off‐Season of Paddy Rice

Abstract

Cassava (Manihot esculenta Crantz) grown in upper paddy fields after rice (Oryza sativa L.) could increase cassava yield and improve land use efficiency. The objective of this study was to evaluate growth, yield, and starch content of four cassava genotypes grown after the harvest of rice in upper paddy fields in Thailand. Four cassava genotypes—cultivars Kasetsart 50, Rayong 9, and Rayong 11—and line CMR38‐125‐77 were evaluated during the 2015–2016 and 2016–2017 growing seasons for five environments. Each experiment had a randomized complete block design with four replications. Soil characteristics were assessed prior to planting, and crop growth and development and local weather conditions were recorded during the experiments. Environment affected all traits, but genotype and genotype × environment effects were nonsignificant for starch content at 180 d after planting (DAP) and for leaf growth rate (LGR) at 120 to 180 DAP. Average storage root dry weights across five environments were 4301, 3933, 3128, and 5824 kg ha−1 for Kasetsart 50, Rayong 9, Rayong 11, and CMR38‐125‐77, respectively. CMR38‐125‐77 was the most stable genotype for storage root fresh and dry weights, and total dry weight. Physiological determinants of both storage root yield and total biomass of cassava were crop growth rate (CGR) and net assimilation rate (NAR) for 30 to 90 DAP and LGR, stem growth rate (SGR), CGR, and NAR for 120 to 180 DAP, as well as storage root growth rate (SRGR) for 90 to 180 DAP. Leaf growth rate during 120 to 180 DAP is likely to be a new criterion for supporting cassava varietal selection. This investigation showed the feasibility of growing cassava between paddy rice seasons.