پژوهشهای زراعی ایران (Dec 2022)
Effect of end of Season Drought Stress on Morphology, Yield Components and Grain Yield of Rapeseed (Brassica napus L.) Cultivars
Abstract
IntroductionWater is now the main limiting factor for crop production in arid and semi-arid regions. Water-cut or irrigation interruption has been suggested as one of the main strategies agro-technique to get the most benefit from limited water resource available. In this regard, plant growth stage, time of stress induction and the genotype are the main key factors to determine the degree of success. Canola is one of the most important oil crop. It can survive some degree of water stress while there is a need for research to find the most appropriate genotypes for plantations in water-limited areas.Materials and MethodsIn order to determine the effect of water stress at the various growing stages of canola genotypes a split-plot experiment was conducted based on the randomized complete block design with three replications at the research farm of the department of plant production and genetics, Agricultural Sciences and Natural Resources University of Khuzestan, Iran during 2020-2021. Main plots included three irrigation treatments: control (without interruption of irrigation), interruption of irrigation in the beginning of the flowering stage (phenology code 60) to the formation of 50% pods (phenology code 75), and interruption of irrigation in the stage of formation of pods until harvest (Phenology code 99) in the main plots and the cultivars (Long pod, Aram, RGS 003, Jankom, Solar, Hayola 4815, Mahtab, Julius, Agamax and Sala) were arranged in sub-plots with respect to irrigation treatments. At the end of the growing season, plant height, number of branches, silique length, number of pods per plant, number of seeds per pod, 1000 grain weight, and grain oil percentage were measured. Also, after removing the marginal effect, economic performance, biological performance and harvest index were measured.Results and DiscussionOur results revealed there was a significant interaction effect between irrigation interruption stress and genotype on all studied traits. The number of sub-branch among cultivars varies as a result of Irrigation interruption stress. The genotypes of the long pod and Hayola 4815 had the highest number of branches compared to other genotypes when irrigation was interrupted at the flowering stage up to 50%, while when applied stress at the stage of flowering up to harvest, genotype, solar exhibited the highest number of sub-branch. The lowest number of sub-branches in all interruption of irrigation and control treatments was obtained by Jankom genotype. The mean comparisons in the conditions without irrigation interruption (control) the highest percentage of seed oil was obtained from Solar (48.3%), Hayola 4815 and 4815 (46.3%), stress application in flowering stage up to 50% sowing of a long pod (45%) and Hayola 4815 (43%) genotypes in the sowing stress to harvest the highest percentage of seed oil from Sala and Long pod genotypes with average (44.3%) the lowest percentage of seed oil in all present treatments belonged to Jankom genotype. In the present study, the highest (2093.8 kg.ha-1) and the lowest (540 kg.ha-1) grain yield and the highest (986.51 kg.ha-1) and the lowest (191.21 kg.ha-1) grain oil yield in both conditions without irrigation interruption (control) and terminal drought stress were obtained from Hayola 4815 and Jankom genotypes, respectively.ConclusionThe highest and the lowest grain yield, seed oil and biological yield were obtained from Hayola 4815 and Jankom, respectively. According to the results, Hayola 4815, long pod and Solar are highly recommended to cultivate in the regions where there is terminal water stress at the end of the growing season.
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