Sushruti Sharma

Production and characterization of somatic hybrids between Solanum tuberosum L. and S. pinnatisectum Dun.

Interspecific somatic hybrids between the dihaploid Solanum tuberosum and the wild species S. pinnatisectum Dun. were produced via protoplast fusion. Protoplast isolation, electrofusion, culture of post-fusion products and regeneration of calli/shoots were undertaken following optimized protocols. Regenerants were characterized for hybridity, ploidy and resistance to Phytophthora infestans (Mont.) de Bery, causal fungal pathogen of late blight disease. From a total of 126 regenerated macrocalli, 12 somatic hybrids were confirmed by possessing species-specific diagnostic bands of their corresponding parents as revealed by RAPD, SSRs and cytoplasmic-DNA analyses. Tetraploid status of the 12 hybrids was determined using flow cytometry analysis. Intermediate phenotypes for leaf, flower, and tuber characteristics and high male fertility were observed in field-grown hybrid plants. Hybrids were highly resistant to foliage late blight based on field assessment for two seasons. In contrast, moderate level of resistance to foliage blight was observed in hybrids based on the detached leaf assay under laboratory conditions. Overall, somatic hybrids with moderate levels of resistance to foliage blight were identified, and these will be useful for in situ hybridization in potato breeding efforts.

Studies on varietal and crop geometry response on production and quality in Capsicum (Capsicum annuum) under naturally ventilated polyhouse

Experiments were conducted under polyhouse conditions for two years to standardize suitable hybrids/cultivars and planting density under high hill conditions of Uttarakhand. Seven hybrids/cultivars (Mahabharath, Manhattan, Natasha, Swarna, Tanvi, Orobelle and California Wonder) and four spacing were taken under study at VCSG College of Horticulture, Bharsar, Pauri Garhwal. To standardize the crop geometry, seven genotypes were planted at a distance of 30 x 30 cm and 45 x 45 cm. The experiment was laid out in randomized block design with 4 replications. Highest yield was observed in Mahabharath hybrid in 30 x 30 cm spacing with marketable yield of 7.87 kg/m2. Hybrid cultivars were superior to open pollinated cultivars in most or yield and yield contributing characters. Highest ascorbic acid (103.2 mg/100g) and acidity (0.384%) was recorded in California wonder and Manhattan, respectively. The incidence of powdery mildew was less at wider spacing than the close one with minimum incidence was recorded in Mahabharath (0.205%). Shelf life of varieties was evaluated in the month of September in individual shrink wrapping (ISW) and open conditions. All varieties could be stored for 20–30 days without loosing much water and other quality. ISW was proved better than open stored capsicum in terms of less water loss (<10%) and less rotting percentage.