Evaluation of morphological traits, yield and yield components of selected varieties of canola in autumn and winter cultivation under different irrigation regimes

  Drought stress is the main factor which limits crops production across the world. Selection of crops that are adapted to the climate of each region, the selection of suitable and resistant to environmental stresses, and the use of high-yielding farming practices play an important role in increasing the efficiency of rare source of irrigation water. Morphological and physiological recognition of drought resistance is important for the improvement of problems caused by drought conditions. In order to evaluate the yield and the yield components of selected canola varieties under different temperature and humidity regimes, a factorial split plot experiment was conducted based on randomized complete block design with three replications for two years (2015-2016) in Karaj region. The study site was a field of the Seed and Plant Improvement Institute, Karaj, Iran (35° 59′ N, 50° 75′ E, at the altitude of 1313 m). The main plot factor was included the growing season in two levels (autumn and winter). Irrigation in three levels (normal irrigation or control, Interruption of irrigation from flowering stage and Interruption of irrigation from podding stage) and spring rapeseed cultivars included Jerry, Julius, Zafar, RGS 003, Hayola 4815 and Zabul 10 were assigned to sub plots. Some traits were studied including plant height, slique number and slique length, seed yield, biological yield, 1000seed weight, harvest index. Data were analyzed using the general linear model (GLM) procedure of the statistical analysis system, SAS. When analysis of variance showed significant treatment effects, Duncan’s multiple range tests was applied to compare the means at P < 0.05. According to analysis of variances, treatments and interaction between treatments had significant effect on studied traits at 5 or 1% statistically levels. According to means comparisons, The results showed that in autumn cultivation under control irrigation, the Julius and the Zabol 10 cultivars with dry matter yield of 5592 and 5536 kg/ha, and under interruption of irrigation from flowering stage condition, Julius cultivar with yield of 2511 kg/ha, and in the case of interruption of irrigation from the podding stage, Julius and Zabul 10 cultivars with yield of 4124 and 3959 kg/ha were superior cultivars. In winter cultivation under normal irrigation conditions, the Julius and the Hyola 4815 cultivars with dry matter yield of 3551 and 3307 kg/ha, and the Hyola 4815 and the Zabol 10 cultivars in interruption of irrigation from the flowering stage with dry matter yield of 1595 and 1542 kg ha-1 and in interruption of irrigation from podding stage with 2308 and 2173 kg ha-1 had the highest dry matter yield. Generally, Application of drought stress and winter planting date led to the reduction of yield in all varieties, the results of two years experiment showed that Jolius and Hyolla 4815 cultivars had the highest grain yield under different irrigation conditions. Hyola 4815 cultivar was also suitable for drought stress (interruption of irrigation in both stages). Therefore, these cultivars can be introduced as suitable cultivars in regions may be faced with drought and non-drought stress during the growth period.