جستجوی مقالات مرتبط با کلیدواژه « photo thermal unit » در نشریات گروه « زراعت »

This research was conducted to compare agro-meteorological indices and yield of short day onion cultivars. The experiment was done in randomized complete block design including 15 cultivars (Seba, Imperateriz, Siroos, 7030, S.V. 4043, X. P. Red, Sweet Ajent, Savana Sweet, Golden I, Primavera, Texas Early White, Texas Early Grano, White Grano, Spidan and Contessa) with four replications at Behbahan Agriculture Research Station, southwest of Iran, for two years (2016-18). Seeds were sown in nursery in early October and seedlings were transplanted in early November. Bulbs were harvested when 50-80% of foliage had senesced and fallen. The differences of growing degree days and helio thermal unit were considerable among cultivars from planting to bulbing stage, however the differences of photo thermal index were not significant among cultivars at this stage. During bulbing and bulb development stage differences of growing degree days, helio thermal unit and photo thermal index were considerable among cultivars. Evaluation the correlation coefficients among yield and agro-meteorological indices during bulbing and bulb development stage suggested significant negative correlation of bulb yield with growing degree days and photo thermal indices. The highest bulb yield, thermal use efficiency and helio thermal unit use efficiency were recorded in Siroos (hybrid cultivar). As the seed price of open–pollinated cultivar is less than the prices of hybrid cultivars and the seed of open-pollinated cultivars could be produced by the growers, therefore, planting of Texas Early Grano (open-pollinated cultivar) is recommended for onion production in Khuzestan province at southwest of Iran.

In order to evaluate the effect of autumn and winter planting on yield and phenology of potato cultivars using thermal indices an experiment was coducted in split plot in time based on a radomized compelet block design with three replications at Behbahan Agriculture Research Station in Khuzestan province, south of Iran in 2014 and 2015. Cultivar (Sante, Savalan and Javid) was considered as main plot and planting season (autumn and winter planting) as sub plot. In Autumn and winter planting seasons tubers were planted in early October and early December, respectively. Tubers were harvested in early March and mid May in autumn and winter planting seasons, respectively. The duration of sprout dvelopement in the autumn planting season was 14 days shorter than winter planting season, but tuber bulking duration was 25 days longer in the latter planting season. Futhermore, growing degree days, helio thermal unit and photo thermal index of sprout development stage in autumn planting season (117.41°C day, 1967°C day hour and 9.29°C day day-1, respectively) were greater than winter planting. However these agro-meteorologial indices at tuber bulking stage (537.58°C day, 4168.79°C day hour and 10.42°C day day-1, respectively) were smaller in winter planting. Yield, thermal use efficiency and helio thermal use efficiency were reduced (18.36, 34.95 and 31.58%, respectively) due to high temperatures encountered during tuber bulking stage in winter planting as compared with the autumn planting season. The highst yeild, thermal use efficiency and helio thermal use efficiency in both of planting seasons belonged to Javid cultivar.