تاثیر منبع تامین نیتروژن بر عملکرد کمی و کیفی ژنوتیپ‌های گشنیز (coriandrum sativum l.) در شرایط رقابت با علف‌های‌هرز

به‌منظور بررسی تاثیر منبع تامین نیتروژن بر صفات کمی و کیفی ژنوتیپ‌های گشنیز در شرایط رقابت و عدم رقابت با علف‌های هرز آزمایشی به‌صورت فاکتوریل در قالب طرح بلوک‌های کامل تصادفی با سه تکرار در مزرعه تحقیقاتی دانشکده کشاورزی دانشگاه شاهد در سال 1399 انجام شد. عوامل آزمایش شامل ژنوتیپ‌های گشنیز (نهاوندی، پیشگام، اتیوپی) و منابع کود نیتروژن (اوره، اوره با پوشش گوگردی، شاهد) در شرایط وجین دستی و بدون وجین علف‌های هرز بودند. نتایج نشان داد ژنوتیپ پیشگام دارای بالاترین توانایی تحمل رقابت (45.5) و کمترین تغییر در پتانسیل عملکرد (54.48) و ژنوتیپ نهاوندی دارای پایین‌ترین شاخص تحمل (9.6) و بالاترین تغییر در پتانسیل عملکرد (99.33) بود. تغذیه گیاه با کود نیتروژن توانست به‌طور معنی‌داری عملکرد گیاه را در شرایط عدم حضور علف‌های هرز افزایش دهد. در بین ژنوتیپ‌ها، اتیوپی (563.01 کیلوگرم در هکتار) دارای بالاترین عملکرد دانه بود اما بین تیمارهای کودی و ژنوتیپ‌ها، در شرایط رقابت با علف‌های هرز تفاوت معنی‌داری مشاهده نشد. براساس نتایج اثر متقابل کود نیتروژن در ژنوتیپ بر درصد اسانس معنی‌دار شد. ژنوتیپ اتیوپی تیمارشده با کود اوره بیشترین و ژنوتیپ نهاوندی تیمارشده با کود اوره کمترین درصد اسانس را داشتند. بالاترین درصد لینالول به‌عنوان اصلی‌ترین ترکیب شناسایی‌شده در اسانس گشنیز، متعلق به ژنوتیپ نهاوندی تیمارشده با کود اوره با پوشش گوگردی بود. به‌طور کلی درصد ترکیبات اسانس، بین ژنوتیپ‌های مختلف نتایج متفاوتی را نشان داد که نشان‌دهنده‌ی تاثیر‌گذاری ژنتیک بر این ترکیبات می‌باشد.

effect of nitrogen sources on quantitative and qualitative yield of coriander (coriandrum sativum l.) in competition with weeds

introductionone of the important challenges in the agricultural sector is the low use efficiency of chemical fertilizers, especially nitrogen fertilizers, as well as the competition of weeds with crops. in this regard, it is important to use management solutions to reduce the use of chemical inputs. to increase the quality level of food used by humans while reducing environmental pollution. one of the management solutions is the use of controlled-release fertilizers. considering the desire to increase the quantity and quality of the coriander plant and also to identify the best-studied genotype, research was conducted in this field to investigate the effect of different sources of nitrogen fertilizer and the competition of weeds in the region on the agricultural and medicinal properties of different genotypes of coriander. materials and methodsthe experiment was carried out in factorial form based on a randomized complete block design with three replications in the teaching and research farm of the faculty of agriculture shahed university of tehran in the 2019 season. an experimental treatment consisted of three factors including: 1) nitrogen fertilizer sources (control treatment: without nitrogen fertilizer; scu: with rate of n, 70 kg ha-1, and urea: with rate of n, 70 kg ha-1), 2) genotypes (nahavandi, pishgam and, ethiopia), and 3) weeding (weedy and weeding by hand). the experimental plot size was 2×2 m2 dimensions with a plant spacing of 25 cm ×10 cm. a space of 1.5 m between plots and 2 m between blocks were maintained. at the end of the growth period, coriander plants of 1 m2 per plot were harvested, and fruit yield per plot was measured. also, in the plots under weed competition, the competition index was evaluated. sampling of weeds was done in two stages (in the growing stage of the main plant and another in the ripening stage of the seeds) using quadrats of 30 x 30 cm and the abundance and biomass of each plot was calculated. to evaluate the percentage of the essential oil of coriander seeds, the clevenger device was used with the steam distillation method to identify and determine the essential oil compounds extracted from the gas chromatography device.results and discussionrelated to the competitive indices, results showed that, the pishgam genotype had the highest ability to withstand competition (%), and the lowest yield loss (%), and, the nahandi genotype had the lowest ability to withstand competition (%) and the highest yield loss (%). it seems that the pishgam genotype was more successful in competing with weeds due to its early maturity and higher germination rate. so, it has a higher ability to tolerate weed competition than other genotypes. regarding fruit yield, the findings of this experiment revealed a significant increase in yield with the application of nitrogen fertilizer in the weeded plots. additionally, the ethiopian genotype exhibited the highest fruit yield among the weeded plots. however, the fruit yield of genotypes did not show significant differences in the un-weeded plots. this suggests that weed competition significantly limited fruit yield compared to the inherent characteristics of the genotypes assessed in this trial. ethiopian genotype showed the highest percentage of essential oil in all nitrogen fertilizer sources. in the pishgam genotype, the most essential oil was obtained in the sulfur-coated urea treatment but, in the nahavandi genotype, the most essential oil belonged to the control fertilizer treatment. due to the difference in the genetic structure of genotypes, various results have been observed, which can be due to the difference in the fertility of different genotypes. also, the results of this experiment showed that the main composition of coriander essential oil is linalool.conclusionthe results showed that n fertilizer and weeding significantly increased seed yield. and the ethiopian genotype had the highest seed yield and essential oil in weeded plots. also, the pishgam genotype had the highest ability to withstand competition (%) and the lowest yield loss (%).