تاثیر کودهای مختلف زیستی و ترکیب آن‌ها بر خصوصیات کمی و کیفی گل زعفران در رژیم‌های مختلف آبیاری

به منظور مطالعه خصوصیات کمی و کیفی گل زعفران تحت تاثیر کودهای مختلف زیستی و رژیم‌های آبیاری، آزمایشی طی دو سال زراعی  01-1400 و 02-1401 در اراضی کشاورزی شهر زیار اجراء شد. این آزمایش به‌صورت کرت‌های خردشده در قالب طرح بلوک کامل تصادفی با سه تکرار انجام شد. در این آزمایش کم‌آبیاری در سه سطح (50، 75 و 100 درصد) به‌عنوان عامل اصلی و باکتری‌های آزادزی تثبیت‌کننده نیتروژن (b-n)، باکتری‌های حل‌کننده پتاسیم (b-k)، باکتری‌های حل‌کننده فسفات (b-p)، ترکیب آن‌ها و شاهد بدون کود در هشت سطح به‌عنوان عامل فرعی بودند. نتایج نشان داد بیشترین تعداد گل (79.9 عدد در متر مربع)، وزن تر گل (31.4 گرم در متر مربع)، وزن خشک کلاله (0.492 گرم در متر مربع)، وزن خشک خامه (0.122 گرم در متر مربع) و وزن خشک گل بدون کلاله و خامه (5.09 گرم در متر مربع) در تیمار 100 درصد نیاز آبی و کود زیستی npk بدست آمد. از سوی دیگر نتایج خصوصیات کیفی زعفران نشان داد بیشترین میزان کروسین (253 میلی‌گرم در گرم)، پیکروکروسین (35 میلی‌گرم در گرم) و سافرانال (121 میلی‌گرم در گرم) در تیمار 75 درصد نیاز آبی و کود زیستی npk بدست آمد. در نهایت، برای داشتن عملکرد مطلوب، بهترین تیمار، آبیاری 100 درصد نیاز آبی و کود زیستی ترکیبی npk بود در حالی که از نظر کیفی، آبیاری 75 درصد نیاز آبی به‌همراه کود زیستی ترکیبی npk دارای بهترین تیمار بود.

impact of various biofertilizers and their combinations on the quantitative and qualitative characteristics of saffron flowers under different irrigation regimes

introduction: proper nutrient management is becoming a key component in enhancing crop yield under variable environmental conditions, as it supports plant growth and tolerance to severe constraints such as drought stress and soil impoverishment. biofertilizers, in addition to regulating nutrient uptake, serve as an effective alternative to chemical fertilizers, ensuring sustainable, safe, and stable agricultural production and biomass. given the benefits of biofertilizers, formulating an appropriate fertilizer combination that prevents excessive yield reduction under limited water resources is crucial. materials and methods: to study the quantitative and qualitative characteristics of saffron flowers under the influence of various biofertilizers and irrigation regimes, an experiment was conducted over two agricultural years (2021-2022 and 2022-2023) in the agricultural lands of ziar city. this experiment was implemented as split plots in a randomized complete block design with three replications. in this experiment, deficit irrigation at three levels (50%, 75%, and 100%) was considered as the main factor, and free-living nitrogen-fixing bacteria (b-n), potassium-solubilizing bacteria (b-k), phosphate-solubilizing bacteria (b-p), their combinations, and a control without fertilizer at eight levels were the sub-factors. the water requirement for saffron was estimated at 3,280 cubic meters per hectare using the cropwat software, based on long-term meteorological data from 1994 to 2018. irrigation was conducted using a meter and in basin irrigation method. in the first year, the first irrigation was done immediately after planting. overall, four irrigation sessions were carried out each year (before flowering, after flowering, mid-march, and late april). the irrigation amounts for the 50%, 75%, and 100% treatments were 1,640, 2,460, and 3,280 cubic meters, respectively. due to the intense competition of weeds with the crop and the prevention of growth, and because the experiment was focused on the effect of biofertilizer on the plant, the use of herbicides was not feasible. therefore, weed control was manually done twice in february and april in both experimental years. results and discussion: the results indicated that the highest number of flowers (79.9 m-2), fresh flower weight (31.4 g. m-2), dry stigma weight (0.492 g. m-2), dry style weight (0.122 g. m-2), and dry flower weight without stigma and style (5.09 g. m-2) were obtained in the 100% water requirement treatment combined with npk biofertilizer. on the other hand, the qualitative characteristics of saffron showed that the highest amounts of crocin (253 mg. g-1), picrocrocin (35 mg. g-1), and safranal (121 mg. g-1) were achieved in the 75% water requirement treatment combined with npk biofertilizer. conclusion: overall, the results of this experiment demonstrated that with increasing stress intensity from 100% to 50% water requirement, the characteristics such as fresh flower weight, number of flowers, dry stigma weight, dry style weight, and dry flower weight without stigma and style decreased. on the other hand, at all three levels of water requirement, the application of various biofertilizers (nitrogen-fixing bacteria, phosphate-solubilizing bacteria, and potassium-solubilizing bacteria) either singly, in pairs, or in triplets mitigated the negative effects of stress, although the dual and triple combinations had more positive effects. additionally, the qualitative traits results showed that in all fertilizer treatments, applying the irrigation regime from 100% to 75% increased the amounts of crocin, picrocrocin, and safranal, but with the increase in stress intensity to 50%, the amounts of these traits decreased, although different biofertilizers reduced the negative effects of stress. ultimately, to achieve optimal performance, the best treatment was 100% water requirement irrigation combined with npk biofertilizer, while in terms of quality, 75% water requirement irrigation combined with npk biofertilizer was the best treatment.