Influence of red-blue light ratio on the phenology and morphology of different lentil (Lens culinaris Medik) and chickpea (Cicer arietinum) genotypes under a simple and resource-efficient in-house speed breeding method based on the application of extended photoperiod

In the complex context of rising food demand, natural resources degradation and worsening climate changes impact, food legumes could play an important role in sustainable agriculture and food security. To overcome these challenges, enhanced genetic gain has become a necessity. Speed breeding-based extended photoperiod is being used to reinforce conventional breeding methods and to speed up the development of adapted varieties. Speed breeding growth chambers and greenhouses' light quality in terms of red-blue ratio is among important factors that need to be optimized to enhance the efficiency of this technique to accelerate plant growth and development while limiting plant stress. We have compared the effect of different light ratios of 5:3 red-blue, 3:5 red-blue and 4:4 white-white on phenological and morphological characteristics of three lentil and chickpea genotypes grown in a speed breeding-based extended photoperiod growth chamber with 22 h light/2 h dark. The 5:3 red-blue light ratio increased plant height and reduced flowering time for the three tested lentil varieties with 36, 41 and 40 days after sowing, respectively, as well as for the three tested chickpea varieties with 42, 38 and 24 days after sowing, respectively. While the 3:5 red-blue ratio increased leaves and secondary stem growth for lentil; leaves and secondary stem growth, green canopy cover and seedling vigour for chickpea. Less vegetative growth and later flowering were observed under white light. Higher red-blue light ratio of 5:3 accelerated lentil and chickpea vegetative growth and flowering, making it more optimal for speed breeding-based extended photoperiod. It should be pointed out that the suggested home-designed and built protocol is cost-effective and easy to implement especially in small-scale breeding programmes in developing countries.