Bioenergetic Limitations to Breeding Better Brassicas

Abstract

Crop production is an energy conversion process in which the incident light energy is trapped and converted to chemical bond energy during photosynthesis. This energy is used for growth and maintenance of different plant tissues, part of which is allocated to protect the plant from insects and pathogens, and a part towards the reproductive effort (Bazzaz et al. 1987). Plants produce seeds for their self-perpetuation and hence store carbon, nitrogen and other nutrients for the initial growth of the future seedling. In Brassica oilseeds, the main reserves are in the form of lipids, proteins and carbohydrates. The high lipid content in the seeds is exploited for extracting oil. Thus, essentially, the breeding and agronomy research in the Brassica oilseeds aims at maximizing the trapping and conversion of solar energy—a free resource into nutritionally desirable lipids within the constraints of temperature, water, nutrients, biotic and abiotic stresses. The energy content of the oil (39.80 MJ/ Kg) is much higher compared to that of the proteins (23.88 MJ/Kg) and carbohydrates (16.76 MJ/Kg). Because of the higher amount of oil, energy content of Brassica seeds (25.7 MJ/Kg) is higher than that of cereals (17 MJ/Kg) and pulses (18.3 MJ/ Kg).