Aggressiveness of Verticillium dahliae isolates from three vegetative compatibility groups (VCGs) was tested on potato and tomato. VCG4B was the most aggressive to potato and VCG2A was the most aggressive to tomato; VCG2B was the least aggressive to both potato and tomato. In potato, disease incidence, symptom severity and colonization index of stem segments were significantly higher in plants inoculated with VCG4B isolates than in those inoculated with VCG2B and VCG2A isolates. Inoculation with VCG4B and VCG2A decreased plant height and fresh weight more than inoculation with VCG2B. In tomato, VCG2A caused significantly more severe symptoms than either VCG4B or VCG2B. The colonization index in tomato plants inoculated with VCG2A was also significantly higher than in those inoculated with VCG4B and VCG2B. Similar patterns of relative aggressiveness were observed in potato and tomato when the pathogenicity of isolates of various VCGs, each originating from a specific host (cotton, potato or eggplant), was compared.

The present study was undertaken at ICAR-CTCRI, Sreekaryam to identify and group N and K efficient genotypes from a pool of released varieties, pre-breeding lines and elite landraces of cassava during 2021-2022. Thirty genotypes of cassava were evaluated for their diversity based on N and K efficiency along with some of its contributing plant characters using statistical tools like principal component analysis, and dendrogram clustering. The variation existing among the selected genotypes was observed through PCA, where the first six principal components accounted for nearly 81% of the total variability. Characters like tuber yield, plant height, stem girth, tuber length and tuber girth contributed to the greater variability among the genotypes. The dendrogram analysis classified the genotypes into six clusters based on the 18 parameters contributing to nutrient use efficiency. The proportion of the variance accounted by these clusters came up to the extent of 50% displaying the association of the genotypes with similar characters in these clusters. These analyses helped to realize the wide range of variability existing among the selected genotypes for the 18 characters studied.  A simple correlation was also worked out between N and K use efficiency with root traits, which revealed that characters such as weight of storage roots, number of storage roots, and number of basal roots showed a positive correlation with both N and K use efficiency in cassava.