Eggplant (Solanum melongena L.) is a widely cultivated vegetable in India with enormous variability. Recent molecular techniques revealed three closely related but distinct Solanum species (S. melongena, S. incanum and S. insanum), with the Indian subcontinent being a domesticated centre. Spontaneous hybridization between S. insanum and S. melongena has led to the formation of naturally introgressed lines and limited studies are available to differentiate these genotypes using morphological key traits. Current study aimed to delineate naturally introgressed genotypes of Indian eggplant collections using morphological key traits for plant genetic resources (PGR) management and assess available genetic diversity. The study characterized a collection of 157 eggplant germplasm at ICAR-NBPGR, Regional Station, Kerala, and identified 30 naturally introgressed, 10 wild progenitors and 117 cultivated eggplants. The key morphological traits are prickliness (stem, petiole, calyx and pedicle), leaf base shape, fruit shape and size. Other fruit traits such as length, breadth and mesocarp texture could also provide some clues for delineating introgressed genotypes from S. insanum and S. melongena. Basic statistical analysis of six quantitative traits of 157 eggplant genotypes revealed the presence of considerable amount of variation (CV%) in which fruit length/breadth ratio showed higher variation (73.87) followed by fruit length (54.73) and average fruit weight (53.5). The frequency distribution of 14 qualitative traits revealed the presence of all character states among them. Key traits identified under study could provide clues to identify individual plants at field level to plant taxonomist/explorers and also to aid gene bank curators for PGR management.

A total of 1968 accessions of cultivated eggplants, belonging to Solanum melongena and Solanum aethiopicum and procured from the IVC/JAAS (Nanjing) and IVC/ZAAS (Hangzhou), China, were examined for 23 morphological traits, such as characteristics of plant, stems, leaves, flowers, fruits and original geographic information. A comprehensive numerical classification methodology, including two types of genetic distance, viz. Mahalanobis (Ma) distance and Euclidean (Eu) distance; four clustering methods, viz. unweighted pair group average (UPGA), Ward's (W), complete linkage (CL) and single linkage (SL) methods; three sampling strategies, viz. random (R), preferred (P) and deviation (D); and four sampling sizes (10, 15, 20 and 30% of initial collection), was used to divide all accessions into main groups and subgroups for the establishment of candidate collections. The evaluation of these candidate collections showed that a combination of Eu distance, UPGA clustering method, and R or P sampling strategy with sampling size at 15–20% was suitable for establishing the core collection, providing an adequate and representative genetic diversity of the initial collection of the cultivated eggplants.

Studies conducted on the spatial pattern of Leucinodes orbonalis Guen. larvae at the Experimental Farm, Barapani of ICAR Research Complex for NEH Region, Shillong revealed that they follow positive binomial distribution within plant, shoot and fruit. The larvae were distributed as negative binomial (contagious) within plot (2 × 2 m) at all stages of sampling except during initial and last stages of crop where they follow positive binomial distribution. The possible reason for this change in distribution may be due to comparatively lower larval densities at initial and last stages of crop.

During three seasons of observations similar populations of the jassid Empoasca lybica were recorded on two different eggplant cultivars (cvs). However cv Black Beauty exhibited more tolerance to jassid attack than cv Long Purple. Comparing jassid-infested and jassid-free treatments, the growth and yield of Long Purple plants were reduced more drastically by the insect than were those of Black Beauty.