Influence of P-Ca on cytokinins in xylem sap and on stomatal resistance in apple

With the purpose to search upon the cytokinins origin, a study was conducted on the effects of prohexadione-ca (P-Ca) on cytokinins in xylem sap and on stomatal resistance in apple. Golden Delicious seedlings were sprayed with 100 ppm P-Ca. Stomatal leaf resistance was measured at intervals between 1 and 4 hours of spraying and 15 days after the treatment. Golden Delicious trees were sprayed with 200 ppm P-Ca two weeks after full bloom. At intervals between 1 and two weeks after P-Ca treatment, the main de-shooted stem was removed from root system and xylem sap was collected for cytokinins analysis using the suction technique. Prohexadioneca significantly increased stomatal resistance (range 2.74-4.35 s/cm−1) when compared to control (range 2.12-3.44 s/cm−1); however, P-Ca did not modify the level of cytokinins in xylem sap since range values were between 0.10 to 0.20 μg kinetin equivalents/20 ml xylem sap for both, cytokinin and control.

Development of F1 hybrids of cabbage with complex resistance in the south of Russia

Relevance Breeding for resistance is one of the priorities when working with late-ripening cabbage.The most significant damage to this crop in the south of Russia is caused by diseases such as fusarium, black rot, and from pests – tobacco trips. Methods The purpose of the research is development of heat-resistant hybrids of medium-late and late maturity of various areas of use with complex resistance. For 2 decades much attention was paid to breeding and immunological work on development of inbred lines with group resistance: to fusarium and polygenic resistance to black rot. The study of race-specific resistance for better protection against black rot began in 2013. At that, the progeny of the lines were eveluated, which were selected by hydathogenic polygenic resistance on the infectious background of cabbage during inoculation of plants with the Krasnodar population of the pathogen.Since specific resistance to a particular race inherited in white cabbage is recessive and it is very difficult to develop lines and hybrids resistant to several races, a strategy was chosen to increase resistance to this dangerous disease based on a combination of field resistance, stem resistance to the main race 1 and leaf resistance to one or two races. Results As a result of the work carried out in 2018, 44 lines of medium-late maturity with stem resistance to race 1 were selected, of which a significant part of the lines had leaf resistance to a particular race, including 4 lines resistant to races 1 and 4, 1 line – to races 0, 1,4, and 1 line – to races 0, 3, 4. The heat-resistant hybrid for processing Sudarynya was passed to State Variety Testing, it has one parent with stem resistance to race 1, leaf resistance to races 0, 1.4 and hydatode resistance, and the second parent has stem resistance to race 1 and hydatode resistance. Every year, hybrids are evaluated for thrips damage. According to the results of the evaluation of hybrids, lines with a high tolerance to tobacco thrips were identified. In 2017-2018 9 lines with complex resistance to fusarium, black rot and thrips (Ten211, Yas111, Eubi122, Hn861, Hn270-21, Hn270-24, Br272-22, Hn270-14p-1, 272-510) were selected, on the basis of which promising combinations of economically valuable traits were obtained.

Variability and heredity of some qualitative and quantitative grapevine characteristics

Variability and mode of heredity of some important qualitative and quantitative grapevine characteristics in 45 seedlings of F1 generation obtained from crossing combination Seedling 113 x Muscat Hamburg were investigated in this study. The seedlings of F1 generation for the investigated characteristics were arranged in certain number of categories by the OIV method. As variability indexes, standard deviation (S) and coefficient of variation (V) were used. Evaluation of the mode of heredity was done by ?2 test and t-test. Considering examined characteristics, the highest variability showed grape yield (V=58.9%), and the lowest sugar content in must (V=16.3%). Color of berry skin, cluster resistance to Botrytis cinerea and leaf resistance to Plasmopara viticola showed monogenic mode of heredity. Exception from the monogenic mode of heredity was determined for the flavor of berry. Grape yield, bunch weight and berry weight showed negative heterosis. For the sugar content in must, domination of the parent with low sugar content in must was determined.

Partitioning hydraulic resistance in Sorghum bicolor leaves reveals unique correlations with stomatal conductance during drought

The hydraulic architecture of leaves represents the final path along which liquid water travels through the plant and comprises a significant resistance for water movement, especially for grasses. We partitioned leaf hydraulic resistance of six genotypes of Sorghum bicolor L. (Moench) into leaf specific hydraulic resistance within the large longitudinal veins (r*LV) and outside the large veins (r*OLV), and correlated these resistances with the response of stomatal conductance (gs) and photosynthesis (A) to drought. Under well-watered conditions, gs was tightly correlated with r*OLV (r2 = 0.95), but as soil moisture decreased, gs was more closely correlated with r*LV (r2 = 0.97). These results suggest that r*OLV limits maximum rates of gas exchange, but the ability to efficiently move water long distances (low r*LV) becomes more important for the maintenance of cell turgor and gas exchange as soil moisture declines. Hydraulic resistance through the leaf was negatively correlated with evapotranspiration (P < 0.001) resulting in more conservative water use in genotypes with large leaf resistance. These results illustrate the functional significance of leaf resistance partitioning to declining soil moisture in a broadly-adapted cereal species.