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The significant reduction of bollworm infestation by the implementation of Integrated Pest Management (IPM) in Bt Cotton as a component of IPM led to reduction in bollworm infestation and increase in yield. However, these alterations have brought in many new biotic problems hitherto unknown or of little economic importance. Field survey of rainfed Bt cotton fields in Perambalur district of Tamil Nadu, India during 2008-2014 revealed that the incidence of various insect pests and plant diseases is on the rise in different Bt cotton hybrids. In 2008-2009, it was observed that the Bt cotton was damaged by cotton mealybug (Phenacoccus solenopsis Tinsley), green mirid bug (Creontiades biseratance Distant) and root rot (Rhizoctonia solani Kuhn) which caused severe yield losses. In addition to that, other pests like papaya mealybug (Paracoccus marginatus Williams & Granara de Willink) and Alternaria leaf spot caused more damage in Bt cotton during 2009-10. Besides these pests, the mirid bug (Campyloma livida Reuter), stripped mealybug (Ferrissia virgata Ckll), tobacco streak virus, grey mildew Ramularia areola and boll rot incidence in Bt cotton were noticed in 2010-12. Apart from this pest and disease problems, the Alterrnaria leaf blight, root rot (Macrophomina phaseolina Maubl) and Myrothecium leaf spot caused severe yield losses in Bt cotton during 2012-2014. The survey revealed that, the pests and disease problems are increasing year by year in Bt cotton which caused yield reduction and also increased the cost of cultivation. If left unchecked these pests and disease problems are capable of undoing all benefits gained due to Bt cotton in terms of increased yield and reduction in use of chemical pesticides.

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Yellow Vein Mosaic Virus (YVMV) disease of okra is the single major production constraint and causes yield loss to the tune of 50-90% in India. Hence continuous search for new sources of resistance and development of better varieties/hybrids with durable level of resistance should receive attention of breeder. An attempt was made to screen twenty-six advanced lines/varieties of okra in one of the hot spots of YVMV disease in eastern India to identify suitable parents for resistant breeding program. The study revealed high magnitude of genetic variability and high degree of transmission of majority of the growth, earliness, and yield component traits under consideration. Based on the degree of divergence, the genotypes were grouped into four clusters. Hybridization between genotypes belonging to Cluster II and Cluster III could combine early maturity, higher yield, and having high tolerance against YVMV disease. Dendrogram among the genotypes also revealed high diversity along with strong inter cluster relationships. Based on averages and principal component analysis, six genotypes viz., BCO-1, A. caillei, A. manihot, 11/RES-6, VNR Green and 12/RES-2 appeared very promising candidates for future use in resistant breeding programs.

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Exploitation of heterosis is one of the potential means for improvement of sweet pepper (Capsicum annuum var. grossum L.) that can further be utilized for identification of desirable recombinants. Promising hybrids could be acceptable to growers of tropical and subtropical climates if it is a high yielder with attractive fruit colour and blocky shape. Seven diverse parents were selected through multivariate analysis and were crossed in half diallel mating design to determine the extent of heterosis, mode of gene action, combining ability effects, and dominance estimates for 18 quantitative characters. Expression of fruit colour and shape at physiological maturity stage in the F₁ generation indicated the dominance of red coloured group over other fruit colour groups and dominance of blocky fruit shape over elongate and round fruit shape. Preponderance of non-additive gene action for most of the characters under study suggested the usefulness of exploitation of hybrid vigour. Three genotypes, 8/4, C/4, and Baby Bell were found most promising donors. The hybrids, Arya×Baby Bell, 8/4×Baby Bell and C/4×8/4 were identified as promising based on per se performance, heterosis manifested, and relevance of specific combining ability effects, for possible commercialization under low cost protected structure of tropical and subtropical climates after critical testing. Partial to over dominance response in inheritance of most traits contributed to the genetic basis of heterosis. Isolation of pure lines from the segregating generation of heterotic hybrids emerged as a promising approach to develop line-bred variety having improved fruit yield and quality.