ارزیابی تغییرات راندمان مصرف نور و شاخص‌های رشد ارقام کلزا در شرایط قطع آبیاری و سطوح افزایش یافته‌ تراکم بوته

با توجه به اهمیت شاخص های رشد گیاه زراعی و تاثیر  آن بر میزان جذب نور در شرایط قطع آبیاری، این پژوهش در سال زراعی 1401-1400 در دانشگاه علوم کشاورزی و منابع طبیعی خوزستان به صورت اسپلیت فاکتوریل در قالب طرح بلوک های کامل تصادفی با سه تکرار اجرا شد. در این پژوهش قطع آبیاری (شاهد (بدون اعمال قطع آبیاری)، قطع آبیاری از مرحلۀ گلدهی تا 50 درصد خورجین دهی و قطع آبیاری از مرحلۀ خورجین دهی تا برداشت) به عنوان عامل اصلی و ارقام (هایولا 4815 و آرام) و تراکم بوته (80، 110 و 140 بوته در متر مربع) به عنوان عامل فرعی در نظر گرفته شدند. طی آزمایش تغییرات شاخص های رشد شامل شاخص سطح برگ ( lai)، شاخص دوام سطح برگ (lad) ، سرعت رشد نسبی (rgr)، سرعت رشد گیاه (cgr) و ماده خشک تجمعی (tdw) و کارایی مصرف نور (rue) و تشعشع فعال فتوسنتزی (par) ارزیابی شد. تغییرات شاخص برداشت، دوام سطح برگ و تجمع ماده خشک در ابتدای توسعۀ برگ ها تا کمی قبل از ظهور گل آذین روندی کند داشت، اما پس از آن شیب افزایش شاخص های  ذکر شده بیشتر گردید. براساس نتایج بدست آمده در سطوح مختلف شاهد و قطع آبیاری rue86 بین مقادیر 1.544-0.588 گرم ماده خشک بر مگاژول و rue100 بین مقادیر0.858-0.255 گرم ماده خشک بر مگاژول متغیر بود. به نظر می‌رسد تیمار قطع آبیاری مرحلۀ دوم در تراکم 80 بوته در متر مربع و رقم هایولا 4815 با حفظ سطح سبز بیشتر از طریق دوام سطح برگ بیشتر و استهلاک نوری پایین تر در شرایط قطع آبیاری انتهایی فصل رشد، توانست rue100 بالاتری در مقایسه با سایر تیمارها به خود اختصاص دهد. بیشترین میزان عملکرد دانه(1572.61 کیلوگرم در هکتار) نیز به تراکم 110 بوته در متر مربع و رقم هایولا 4815، اختصاص یافت.

evaluation of phenological characteristics, light consumption efficiency and growth indicators of rapeseed cultivars under the condition of no irrigation and increased levels of plant density

introductiongrowth analysis has a significant perspective on the function of agricultural plants. in the early stages of plant growth, the growth indicators, including the leaf area index, the growth rate of the product decreases, and then due to suitable vegetation, the absorption of light radiation is better, and the accumulation of plant dry matter also increases, and after that due to aging and yellowing, the leaves are reduced. the amount of light radiation absorbed by the plant varies during the growth period, which depends on the leaf surface index and the arrangement of the leaves of the plant. material and methodsthe experiment was conducted in the research farm of khuzestan university of agricultural sciences and natural resources in 2021-2022. in this research, the effect of three factors of irrigation interruption, cultivars and density was investigated in the form of factorial split with the base design of randomized complete blocks in three replications. the factor (no interruption of irrigation (control), interruption of irrigation at the beginning of flowering until the formation of 50% of the pod and interruption irrigation at the stage of pod formation until harvest the main factor, rapeseed cultivars hayola 4815 and aram and plant density per meter square (80, 110 and 140 plants per square meter) were considered as secondary factors. results and discussionirrigation interruption caused a decrease in growth indicators, including the amount of plant dry matter accumulation, leaf surface index, and leaf surface durability. the changes in harvest index and durability of leaf surface and accumulation of dry matter at the beginning of the development of leaves had a slow trend until a little before the appearance of inflorescences, but after that the slope of the mentioned parameters increased. during the experiment, changes in growth parameters including lai, lad, rgr, cgr and tdw were evaluated. at the beginning of the plant growth season, the growth rate of the product was low due to the lack of complete vegetation cover and proper light consumption efficiency. in all treatments, with the passage of time, the growth rate of the crop was gradually increasing and it reached the maximum value in the reproductive stages and then went through a decreasing process. the effects of stopping irrigation on dry weight were evident and the accumulation of dry matter was observed during the increasing time. which can be due to the increase in dry weight of stems, leaves and reproductive organs over time. also the relative growth rate also showed an increasing trend with the increase of the leaf area index at first and then a decreasing trend. conclusionit seems that the second-stage irrigation interruption treatment at a density of 80 plants per square meter and haiola 4815 variety, by maintaining more green area through more leaf surface durability and lower light consumption in the condition of irrigation interruption at the end of the growing season, was able to achieve a higher rue100 compared to other treatments. to dedicate the highest seed yield (1572.61 kg per hectare) was obtained from the density of 110 plants per square meter and hayola variety 4815..