تاثیر تاریخ‎های مختلف کاشت و تراکم بوته بر عملکرد، اجزای عملکرد و کارایی مصرف آب زیره سبز (cuminum cyminum l.) در شرایط کم‎آبیاری در مشهد

به‌منظور بررسی تاثیر سطوح آبیاری، تاریخ کاشت و تراکم بوته بر عملکرد، اجزای عملکرد و کارایی مصرف آب گیاه دارویی زیره سبز آزمایشی در سال زراعی 1397-1396 در مزرعه تحقیقاتی دانشکده کشاورزی دانشگاه فردوسی مشهد به‌صورت کرت‌های خرد شده در قالب طرح بلوک‌های کامل تصادفی با سه تکرار اجرا شد. عامل اصلی شامل سطوح آبیاری 100، 75 و 50 درصد ظرفیت زراعی، سه تاریخ کاشت در ماه­های آذر، اسفند و فروردین به‌عنوان عامل فرعی و دو تراکم کاشت 40 و 80 بوته در مترمربع عامل فرعی فرعی در نظر گرفته شدند. نتایج نشان داد آبیاری کامل زیره سبز در آذر ماه با تراکم 80 بوته در مترمربع دارای بیشترین تعداد چتر در بوته، تعداد دانه در چتر و عملکرد دانه بود. در حالی‌که در شرایط مشابه با کاهش تراکم، وزن 100 دانه و وزن تک بوته افزایش و کارایی مصرف آب کاهش یافت. تیمارهای آبیاری 75 و 50 درصد ظرفیت زراعی در فروردین ماه با تراکم 40 بوته در متر مربع به‌ترتیب با کاهش 53.77 و 52.20 درصدی عملکرد دانه نسبت به کاشت آن در آذر ماه با آبیاری کامل و تراکم 80 بوته در مترمربع، دارای کمترین مقدار بود. همچنین، سطوح آبیاری 100 و 75 درصد ظرفیت زراعی در ماه‌های اسفند و فروردین با تراکم 80 بوته در مترمربع به‌ترتیب علی‌رغم کاهش 12.83، 29.24، 21.43 و 35.11 درصدی عملکرد دانه نسبت به کاشت در آذر ماه با آبیاری 100 درصد ظرفیت زراعی و تراکم مشابه، دارای بیشترین کارایی مصرف آب بودند. بنابراین، با افزایش تراکم بوته در واحد سطح همراه با آبیاری متوسط (75 درصد ظرفیت زراعی) در کشت‌های دیر هنگام (اسفند و فروردین) می‌توان تا حدودی کاهش عملکرد دانه زیره سبز را با افزایش کارایی مصرف آب جبران نمود.

Effects of Planting Date and Deficit Irrigation on Water Use Efficiency of Cumin (Cuminum cyminum L.) at two different Densities in Mashhad Conditions

IntroductionSupplies of irrigation water are severely limited and water use efficiency (WUE) has become more vital, especially for valuable drought tolerant plants. Green cumin (Cuminum cyminum L.) is a medicinal and spices plant adapted to arid and semiarid regions such as Iran. Planting date, irrigation and plant density can affect quality and quantity of cumin. Seed yield of cumin decreases by increasing water deficit, despite absorbing water even in very low water potentials. Changes in planting date can also affect water use efficiency due to rainfall and evapotranspiration (ET) differences between each season. Therefore, crop yield should increase in parallel with decreasing water consumption (or evapotranspiration) for optimal water use and increasing WUE. Additionally, different plant densities and late or early planting dates could affect morphological traits and grain yield.Materials and MethodsIn order to study the effects of planting date, deficit irrigation and plant density on yield, yield components and WUE of cumin, a field experiment was conducted as splitsplit plot based on randomized complete block design with three replications at the Agricultural Research Station, Ferdowsi University of Mashhad during growing season of 20172018. The main plots were irrigation levels including 100, 75 and 50% field capacity (FC). Three planting dates were studied in the split plots (December, March and April) and two plant densities (40 and 80 plant m2) arranged as splitsplit plots. Soil moisture content was determined a day before and two days after each irrigation with TDR. Then, irrigation was done based on treatments during the growth period. Number of umbel per plant, number of seed per umbel, 100seed weight, plant weight, seed yield and WUE were measured at the end of growing season. Analysis of variance were calculated using R software and Duncan apos;s multiple range test was used at 5% probability level to compare the averages.Results and DiscussionThe results showed that the full irrigation (100% FC) of cumin in December with 80 plants m2 had the highest number of umbel per plant, number of seed per umbel and seed yield, whereas, 100seed weight and plant weight increased and WUE decreased with decreasing density (40 plants m2) under 100%FC during December. The lowest seed yield were obtained from 75 and 50% FC in April with 40 plants m2 (53.77% and 52.20% respectively) compared with December with 100% FC and 80 plants m2. Seed yield were decreased by irrigation levels of 100 and 75% FC in March and April with 80 plants m2 12.83, 29.24, 21.43 and 35.11%, respectively compared with 100% FC in December (80 plants m2), despite the highest WUE. Therefore, increasing plant density with medium irrigation in late planting dates (March and April) can partially compensate decreasing cumin seed yield by increasing WUE. The correlation analysis showed that 100seed weight and plant weight had significant negative correlation with WUE in full irrigation and two levels of water deficit. However, there was no significant correlation between WUE and seed yield under both levels of water deficit and full irrigation conditions.ConclusionsThe results of this study indicate that seed yield can be improved by increasing plant density when rainfall is proportional to plant water requirement in autumn and winter. In addition, increasing plant density in medium irrigation (75% FC) conditions in late planting dates (March and April) can increase WUE and produce high economic value.