The water use efficiency by plants in different breeding periods buckwheat varieties

In the increasing climate aridization context, water effective use by plants is important, which is strongly influenced by photosynthesis and plant transpiration. In these processes’ study, buckwheat plants have pronounced variances, manifested in ontogenesis and during the day at the leaves different tiers level, which accordingly affects the water use effectiveness by plants. The water effective use greatest’ values by plants are observed in the pre-dinner hours (from 9:00 a.m. to 11:00 a.m.) during active vegetative growth and mass seed pouring (20 days flowering phase), when photosynthesis processes are active and transpiration is at an average level. As a breeding result, this buckwheat plants property is enhanced, which has a positive effect on seed productivity growth. Modern crop varieties outperform local populations by an average of 19.5% in water use terms during the flowering + 20 days phase, 19.8% in photosynthesis intensity terms, 3.4% in transpiration intensity terms, and 37% in seed productivity terms. At the same time, their resistance to air and soil drought tends to decrease, which negatively affects the stability and photosynthesis, and transpiration, and yield. On this basis, it is not considered appropriate to use the water effective use indicator by plants to assess the breeding material for drought resistance but to recommend it for the only highly productive genotypes’ identification. The promising forms’ selection can be carried out in the field already in the selection’ early stages - the 1st and 2nd years nurseries selection.