بررسی اثر سال و تراکم بوته بر برخی صفات رشدی، بیوشیمیایی و محتوای اسانس گیاه دارویی زیره سبز (cuminum cyminum l.) تحت شرایط آبیاری در مراحل مختلف رشد

investigation of the effect of year and plant density on some growth traits, biochemical characteristics, and essential oil content of medicinal plant cumin (cuminum cyminum l.) under irrigation at different growth stages

this study aimed to evaluate the quantitative and qualitative responses of cumin (cuminum cyminum l.) to irrigation at different growth stages and varying plant densities, using a split plot design based on a randomized complete block design with three replications. irrigation treatments at five different phenological stages were evaluated in the main plots: irrigation during vegetative, flowering, and seed filling stages as control(i1); irrigation during vegetative and flowering stages(i2); irrigation during flowering and seed filling stages(i3); irrigation only during the flowering stage(i4); and no irrigation(i5). the secondary factor was plant density at three levels: 30, 50, and 100 plants per m sup2;. one week after applying the irrigation treatment during the seed filling stage, leaf samples were randomly collected to measure physiological traits, including photosynthetic pigments and proline, from the youngest leaf in each plot. sampling to measure growth traits and yield components was conducted randomly, avoiding marginal effects, after physiological maturity in early july. the essential oil content of the seeds was extracted and measured using the water distillation method with a clevenger apparatus. seed yield across the treatments ranged from an average of 107.4 to 692kg/ha. the highest cumin seed yield was recorded at a density of 50 plants/m sup2; under the i3 irrigation treatment in the first year. essential oil content varied from 0.96 to 5.44%. the highest essential oil percentage was achieved with plant densities of 30 and 50 plants/m sup2; under the i4 irrigation treatment in the first year. the highest total chlorophyll content was observed at a density of 50 plants/m sup2; under i2 treatment (24.74 micro;g/gfw) and 100 plants/m sup2; under i1 treatment (22.6 micro;g/g fw). in conclusion, to achieve optimal quantitative and qualitative yields in cumin, it is recommended to cultivate cumin at a density of 50 plants/m sup2; with two stages of irrigation during the vegetative (stem elongation) and flowering stages.