Capsicum (hot pepper and bell pepper)

Abstract

Capsicum is one of the most widely consumed vegetables and is also used as a spice for its pungency. Many species of Capsicum are being cultivated worldwide. Capsicums are considered as a commercial crop for their economical value. However, the yield of the crop suffers severely due to abiotic and biotic factors. Among the various abiotic stresses, low moisture and high temperature are the major constraints for productivity. Flowering and fruit-set stages were most sensitive for the abiotic stresses. Wide genotypic variability for abiotic stress tolerance is present in Capsicum species. Significant differences in fruit-set, yield, photosynthetic rates, stomatal conductance, total chlorophyll content, proline, and root characteristics have been reported. Pollen germination and fertilization were better in the tolerant capsicum varieties. Higher activities of hexokinase, phosphofructokinase and invertase in the pollen were responsible for the better pollen germination in the tolerant genotypes. Lesser oxidative stress and better antioxidative enzymes were observed as one of the tolerance mechanisms in the capsicum genotypes. Breeding for abiotic stress tolerance has also been attempted and a few cultivars have also been developed in hot pepper using root characteristics and yield as selection parameters under stress. Transgenic plants have also been developed using osmotin gene overexpression and also by overexpressing certain transcription factors. Enriching the soil microbia with mycorrhiza, Arthrobacter and Bacillus species has given encouraging results in giving abiotic stress tolerance. The use of chemicals like brassinolides, sitosterols, and nitric oxide has been found to improve the tolerance in capsicums. In spite of these management practices, crop improvement, transgenic approaches to overcome the abiotic stresses and emphasis for rootstock breeding is lacking. Therefore, future studies should focus on root and flower traits and also on rootstocks to overcome the abiotic stress in addition to the stress management practices.