Varietal screening for identification of postharvest physiological deterioration tolerance in storage roots of cassava

Abstract

ABSTRACT Postharvest physiological deterioration (PPD) is a constraint in cassava (Manihot esculenta Crantz) and a threat to effective utilization of cassava roots. This study determined the magnitude of variability for PPD tolerance among cassava genotypes and identified new sources of tolerance to PPD. Seventy-six cassava genotypes were evaluated for PPD tolerance at postharvest evaluation intervals of 3, 5, 7, 10, 15, or 20 days after harvest. Repeated measure analysis indicated that differences for PPD reliably depend on time in conjunction with genotype and years. The genotypes were categorized into nine classes using rank-sum statistics involving standardized mean range, PPD, and PPD per day. Nineteen genotypes were tolerant and three were free of symptoms up to 20 days postharvest. Released varieties had tolerance to PPD compared to local varieties and pre-breeding lines. The PPD symptoms were mostly found in peripheral regions and in proximal and distal ends rather than in the mid-region of the root. The presence of the root neck reduced deterioration. Root length, weight, and dry matter content were positively correlated with PPD. The new sources of tolerance may improve the adoption and utilization of cassava.