Adaptiveness of productivity and photosynthesis in buckwheat (Fagopyrum esculentum Moench) landraces and varieties produced at different periods

Crop breeding if aimed mainly at the highest productivity results in a significant loss of defense system activity thus causing a decreased plant resistance to adverse environment factors. Reasonably, more attention is now being paid to evolution base in breeding. With this, we studied the norm of reaction to environment changes in buckwheat ( Fagopyrum esculentum Moench) cultivars and landraces as reflecting plant adaptation potential for photosynthesis and yield production to be further involved in breeding. A total of 11 buckwheat cultivars of which Kalininskaya, Bogatyr’ and Shatilovskaya 5 have been derived in 1930-1970, and Chatyr-Tay, Batyr, Devyatka, Dizain, Demetra, Dikul’ and Bashkirskaya krasnostebel’naya are the modern cultivars, together with landraces k-406 and k-1709 (VIR collection, St. Petersburg) were investigated. For the first time it was shown that in the course of buckwheat breeding no improvements in photosynthesis and production sustainability, as well as in homeostasis of grain formation have been achieved. Modern buckwheat cultivars possess high photosynthesis and productivity under favorable weather conditions, whereas at stresses do not have any significant advantage over their predecessors. In dry 2010 the seed production in modern cultivars was not reliably different from that in landraces and old cultivars, while in 2011-2013 at more favorable water supply and temperature it was on average 67.5 % higher, mostly due to the response of photosynthetic system to growing conditions. When drought occurred during the seed filling phase the photosynthetic activity in leaves decreased on average by 32.1 %, dry mass of the aboveground parts and seeds was lower by 46.7 % and 67.5 %, respectively, compared to those under favorable conditions in 2011-2013. With increasing water deficit the situation becomes worse. At soil moisture of 30 % of full capacity the activity of photosynthesis in buckwheat plant leaves was on average 4.4 times less, and seed production was 41.8 % less compared to the optimal moistening. At that, the losses were significantly higher in modern cultivars, e.g. in the k-1709 plants a 66.1 % decrease was found compared to 78.8 % in Dikul’ and Dozhdik plants. Thus the obtained data suggests a low adaptive potential of modern buckwheat varieties. So we propose to improve the seed formation homeostasis in buckwheat plants. In this regard, the selection of autogamous form and the creation of self-pollinating varieties can be used as more effective approaches. The hybridization with F. homotropicum can significantly improve the viability of self-pollinated inbred lines of buckwheat, which can be successfully used in breeding programs to create autogamous varieties. Moreover, the adaptiveness of the of yield formation processes which are not sustainable enough to guarantee the high and sustainable crop production must be improved. An increased activity and effectiveness of photosynthesis and initial growth seem to be of interest. It is shown that the leaf photosynthetic rate in buckwheat varies plants varies widely from 4.65 to 17.8 μmol CO2×m-2×s-1, which allows to select forms both by hybridizing and using selection within a population