Plant development, flower bud differentiation and yield of short-day varieties depending on temperature

Researches were done in 1999-2002 in the Orel Region. Plantings were done in 1999 (test 1) and 2000 (test 2) and calculations were done in 2000-2001 and 2001-2002 respectively. Soil of the test field was forest medium loamy greyzem. Nine varieties and 6 selected forms were tested. The follow correlations were showed up: a genotype, temperature conditions of growth period and plant productivity. The last was calculated as a sum of its main components: average meanings of shorted tillers (ST) and flower stalk (FS) number per a plant, a flower number per a FS and weight of a berry. A sum of effective temperatures (SET) per a season was 1918.7, 1803.1, 1769.0, 2171.0 deg C in 1999, 2000, 2001 and 2002 respectively. A SET per April and May was 387.8, 344.4 and 205.1 deg C in 2000, 2001 and 2002 respectively. A SET during the period of flower bud differentiation (August-October) was 627.7, 667.5 and 642.3 deg C in 1999, 2000 and 2001 respectively. In test 1 a genotype contribution into crop performance varying was 78.3 and 82.3% in the 1 and 2 years of fruiting respectively and in test 2 was 90.0 and 87.6% respectively. If a SET was high during the period of flower bud differentiation, a number of differentiating buds grew up, but a number of FS developing completely decreased. If a SET did not allow FS to develop completely in autumn, a less part of flowers formed, but in spring additional FS (which were rather weak and with a small flower number) formed under favorable conditions. Flower and fruiting date, forming and intensity of berry growth, a number of shorten shoots of early and medium maturing varieties which would form from axillary buds on ST after maturing period had finished were influenced with SET of spring. The same processes of later maturing varieties were stronger influenced with SET of June and July. Generative organs initiation was affected with SET of August and September and also with number of ST formed once more.