Evaluation of Some Yield Responses of Canola Cultivars under Supplementary Irrigation and Dry Land Conditions

In most arid and semi-arid areas, water limitations are one of the main reasons for the reduced plant growth and yield under irrigation and dry land (rainfed) conditions. The aim of this study was to compare the morphophysiological responses of rapeseed cultivars to supplementary irrigation and dryland conditions. For this purpose, an experiment was carried out as a split plot in the form of a randomized complete block design with three replications during 2017-2018 in the Gachsaran Agricultural Research Station. Irrigation treatments were at four levels (no irrigation=I0, supplementary irrigation at flowering stage=I1, supplementary irrigation at grain filling stage=I2, and supplementary irrigation at flowering stage+ grain filling=I3) in the main plot, and cultivars Hayola 401, R. J. S, and Shirali as factorial in the sub-plots. The results showed that supplementary irrigation increased plant height, number of sub-branches per plant, 1000- grain weight, grain yield, and oil percentage compared to rainfed conditions. With supplementary irrigation, the weight of 1000 grains increased by 32% compared to rainfed. Grain yield increased from 755 in rainfed conditions to 2350 kg.ha-1 with two supplementary irrigations. With two supplementary irrigations, the oil content increased by 11.8% compared to the rainfed conditions. In all irrigation treatments, grain yield and oil content of Hayola 401 were higher than R. J. S and Shirali cultivars. In general, supplementary irrigation improved morphophysiological traits, yield, and percentage of grain oil. In rainfed rapeseed cultivation, with supplemental irrigations at flowering and grain filling, water productivity increased from 0.21 to 0.53 kg m-3 grain yield from 755 to 2350 kg ha-1 and oil percentage from 35.4 to 36.9.