Unravelling genetic diversity in root system architecture of tomato at vegetative, flowering and harvesting stages

Research on root system architecture (RSA) of tomato plant is meagre and yet not fully exploited for crop improvement programme. In the present investigation forty-four tomato genotypes were initially assessed under field condition to reveal variability in their root traits at harvesting stage. These genotypes showed variation in their root length, number of roots, root volume, fresh and dry root weight and were classified as high, moderate and low root performance group in field evaluation. Fifteen of the forty four genotypes were assessed in pot culture to study divergence in root system architectural (RSA) traits at vegetative, flowering and harvesting stages. The genotypes exhibited significant variation for all RSA traits at different growth stages. Average genotypic coefficient of variation (GCV) and genetic advance as percent of mean of RSA traits were the highest at vegetative stage (46.44 & 89.55) followed by harvesting (34.76 & 67.89) and flowering stage (25.72 & 51.06). D2 analysis of RSA traits at vegetative, flowering and harvesting stages grouped the genotypes into 4, 4 and 5 numbers of clusters. PC1 & PC2 together explained 91.65 %, 94.92 % & 79.57 % of total variability at vegetative, flowering and harvesting stages. Total root length had the maximum contribution to the diversity of genotypes both in D2 and PCA analysis for all growth stages. This study reveals that root system architecture of tomato varies at different developmental stages.