بررسی عملکرد و برخی ویژگی‌‌های فیزیولوژیک ارقام کلزا در شرایط تنش خشکی آخر فصل و کاشت تاخیری

به منظور بررسی اثر کاشت تاخیری و تنش خشکی آخر فصل بر صفات عملکرد و اجزای عملکرد، اسیدهای چرب اشباع و غیر‌اشباع، به منظور بررسی اثر تاریخ کاشت و تنش خشکی بر صفات عملکرد و اجزای عملکرد، اسیدهای چرب اشباع و غیر‌اشباع، میزان روغن و گلوکوزینولات دانه و محتوای پرولین کلزا آزمایشی به صورت فاکتوریل اسپلیت‌پلات در قالب طرح بلوک‌های کامل تصادفی با سه تکرار در دو سال زراعی 95-1393 در مزرعه تحقیقاتی موسسه تحقیقات اصلاح و تهیه نهال و بذر کرج اجرا گردید. تیمارهای مورد بررسی شامل تاریخ کاشت در دو سطح شامل: 20 مهر (کشت معمول) و 5 آبان (کشت تاخیری)، آبیاری در دو سطح شامل: آبیاری کامل (شاهد) و تنش خشکی (قطع آبیاری از مرحله خورجین‌دهی) و نیز ارقام و هیبریدهای پاییزه کلزا شامل:neptune, elvise, okapi, tassilo, gkh0224, gkh2624, gkh3705 بودند. نتایج آزمایش نشان داد، که تاریخ کاشت، آبیاری و رقم بر تمام صفات به غیر از اسید اکوزنوئیک معنی‌دار بود. به تاخیر انداختن تاریخ کاشت، تعداد خورجین در بوته، وزن هزاردانه، عملکرد دانه، میزان روغن دانه، اکوزنوئیک اسید و پرولین را کاهش ولی میزان گلوکوزینولات دانه و اسید بهنیک را افزایش داد. بیش‌ترین میزان روغن دانه (6/45 درصد) در حالت آبیاری کامل و کشت معمول و کم‌ترین آن ( 42.2درصد) در شرایط قطع آبیاری در مرحله خورجین‌دهی و کشت تاخیری به‌دست آمد. بالاترین میزان پرولین (21.59 میلی‌گرم بر گرم وزن تر) در کشت معمول و از رقم gkh3705 به‌دست آمد. از نظر عملکرد و اجزای عملکرد، محتوای روغن دانه، اسیدهای چرب اشباع و غیر‌اشباع و میزان گلوکوزینولات، رقم gkh3705 مناسب‌ترین بود. با توجه به نتایج، به نظر می‌رسد تاریخ کاشت 20 مهر و رقم gkh3705 در هر دو شرایط بدون تنش و تنش خشکی می‌تواند به عنوان بهترین تیمار برای سودمندی تولید کلزا در منطقه کرج پیشنهاد گردد.

Study of yield and some physiological characteristics of canola cultivars under the drought stress and delayed planting

IntroductionCanola oil seed species currently hold the third position among oil seed crops and has lowest saturated fatty acids content (Ashraf and Mcneilly 2014). When commercial production was first considered in Iran, site location and planting date were thought to be the two most important cultural decisions. A long term drought stress effects on plant metabolic reactions associates with, plant growth stage, water storage capacity of the soil and physiological aspects of plant. Generally, the number of seed per plant, number of seeds per pod and also seeds weight are considered the yield components of canola (Angadi et al., 2003). A study by Kajdi and Pocsai (1993) on the effects of irrigation on 21 rapeseed cultivars showed that, as irrigation frequency increased, the seed yield increased as well. Indeed, they noticed the high seed yield only in the cultivars with high levels of erucic acid and glucosinolate. Moreover, it has been reported that drought or heat stress during flowering and seed filling stages could stop the flowering and caused decrease of seed formation, oil percentage and the seed yield to decrease (Johnston et al., 2002). If cultivars could be selected in a way that produce an acceptable economic yield in less watering condition and are more stress tolerant under the stress intensity conditions, they would be practically very useful for developing rapeseed cultivation in such regions.Materials and methods In order to study the effect of delayed planting and drought stress on grain yield grain component, saturated and unsaturated fatty acids, oil content and glucosinolate of seeds and proline content of rapeseed, a field experiment was conducted as splitplot arrenged in a Randomized Complete Block Design (CRBD) with three replication in Seed and Plant Improvement Research Institute of karaj in 20142016. Experimental treatments were included sowing dates in two levels included: 20th of October (normal cultivation) and 5th of November (delayed cultivation), Irrigation in 2 levels includes: normal Irrigation (control) and drought stress (irrigation withholding in pod formation) as well as hybrids and hybrids Rapeseed autumn included: Neptune, Elvise, Okapi, Tassilo, GKH0224, GKH2624 and GKH3705.Results and discussion The results of the experiment showed that planting date, irrigation and cultivar were significant on all traits Except for eicosenoic acid, Results showed that delaying the planting date decreased pod number per plant, 1000grain weight yield, oil content, eicosenoic acid proline, whereas behenic acid and seed glucosinolate were increased. The highest oil content (45.59%) was in normal irrigation and normal cultivation, And the lowest (42.16%) was observed in irrigation withholding in pod formation stage and delayed cultivation. The highest content of proline (21.59 mg.g. Fw) was observed in normal cultivation and GKH3705 cultivar. The cultivar of GKH3705 was the most appropriate in terms of yield and its components, oil content, saturated and unsaturated fatty acids and glucosinolate of seeds. According to the results, it seems that normal cultivation and GKH3705 cultivar under without stress and drought stress can be recommended as the best treatment for the benefit of rapeseed production in the Karaj region. Conclusions According to the results of this experiment, the most suitable planting date for the studied cultivars of canola is 20th of October in Karaj area. Among the cultivars under study, GKH3705 also produced the highest grain yield in normal and delayed planting, as well as in normal irrigation and stress conditions. In terms of grain and oil production potential and the composition of unsaturated fatty acids are in the optimum level.