بررسي ارتباط برخي ويژگي‌هاي فيزيولوژيك و بيوشيميايي در ژنوتيپ‌هاي سورگوم دانه‌اي با عملكرد و اجزاي آن در شرايط تنش آبي

Investigation of relationship between some physiological and biochemical characteristics with yield and its components in grain sorghum genotypes under water stress conditions

مقاومت گياهان به تنش خشكي به علت پيچيده بودن اثرات متقابل بين عوامل تنش و نيز تنوع پديده‌هاي فيزيولوژيكي، بيوشيميايي و مولكولي مؤثر بر رشد و نمو گياه بسيار پيچيده است. به‌منظور بررسي اثر تنش آبي بر عملكرد، اجزاي عملكرد، ويژگي‌هاي فيزيولوژيك، مورفولوژيك و بيوشيميايي در ژنوتيپ‌هاي سورگوم دانه‌اي، آزمايشي به‌صورت كرت‌هاي خردشده در قالب طرح بلوك‌هاي كامل تصادفي در سه تكرار، در دو سال زراعي 1393 و 1394 در مزرعه مركز تحقيقات و آموزش كشاورزي و منابع طبيعي خراسان جنوبي اجرا شد. تيمارهاي تنش شامل آبياري معمول، قطع آبياري در مرحله رشد رويشي (رؤيت آخرين برگ به‌صورت لوله‌اي) به‌عنوان تنش شديد و قطع آبياري در مرحله رشد زايشي (50 درصد بوته‌ها در مرحله گلدهي) يا تنش ملايم به‌عنوان عامل اصلي و 10 ژنوتيپ سورگوم دانه‌اي شامل KGS29، MGS2، KGS33، سپيده، KGFS27، MGS5، KGFS5، KGFS17، KGFS13 وKGFS30 به‌عنوان عامل فرعي در نظر گرفته شدند. نتايج نشان داد كه تنش آبي شديد و پس‌ازآن تنش ملايم به‌طور معني‌داري عملكرد دانه، وزن هزار دانه و تعداد دانه در پانيكول را كاهش داد. برهمكنش تنش آبي و ژنوتيپ نشان مي‌دهد كه ازنظر عملكرد دانه ژنوتيپ KGFS13 در شرايط تنش ملايم و آبياري نرمال به همراه KGFS17 در شرايط آبياري نرمال بيشترين و ژنوتيپ KGFS5 در شرايط تنش آبي شديد كمترين عملكرد دانه را دارا بود. نتايج حاصل از همبستگي‌هاي بين صفات موردبررسي نشان داد كه در شرايط نرمال (بدون تنش) صفات ارتفاع بوته، تعداد دانه در پانيكول، درصد قند ساقه، محتواي پرولين آزاد، عملكرد بيولوژيك و شاخص برداشت مي‌توانند در جهت بهبود عملكرد دانه به كار روند. در شرايط تنش آبي، درصد قند ساقه، ارتفاع بوته، دماي كانوپي، محتواي پرولين آزاد برگ بيشترين همبستگي را با عملكرد و اجزاي آن داشتند. به‌طوركلي توجه به جنبه‌هاي ديگر از مقاومت به خشكي مانند شاخص‌هاي فيزيولوژيكي (هدايت روزنه، محتواي نسبي آب، دماي كانوپي) بسيار مهم است.

The yield of each crop is determined by several factors, which affect the growth and development of the plant. These factors include environmental, managerial, and plant factors. Environmental stresses are one of the most important environmental factors, including the most important stresses of drought stress. The aim of this study was to investigate the effects of drought in the vegetative and reproductive growth stages on Yield, its Components and Biochemical traits in grain Sorghum genotypes. Materials and Methods In order to evaluate the effect of water stress on grain yield and its components and Biochemical traits in grain Sorghum genotypes (Sorghum bicolor L.), a field experiment as a split plot design was carried out with 3 replications in 2014 at the research farm of the southern khorassan Agriculture and natural resources research and education center. Water stress treatments including normal irrigation (control), irrigation cut off in vegetative growth stage(emergence of terminal leaf as rolled) and irrigation cut off in generative growth stage(50% of plants in start of flowering) as the main plot and 10 genotypes of sorghum including KGS29, MGS2, Sepideh, KGF27, MGS5, KGF5, KGF17, KGF13 and KGF30 were considered as sub plots. Each plot consists of 4 lines with a length of 6 m and line spacing of 60 cm, between plants on row 10 cm was considered. In addition, between each plot and the adjacent plot a line was considered. To determine the yield components of each plot, half a meter in length was harvested and number of plants, number of panicle, grain yield, 1000 seeds weight and number of seeds per panicle were determined. To determine the yield , after the removal of 2 margin lines and a half meter of beginning and end of each plot, plants were harvested from the surface of 3 square meters. Biochemical parameters including chlorophyll a, chlorophyll b, carotenoids, proline and carbohydrates were measured on the flag leaf after flowering stage in each plot. chlorophyll a content, chlorophyll b, and carotenoid content was done according to Arnon method. Simple correlation coefficients between the characteristics studied under normal conditions and drought stress conditions were calculated using SPSS software version 13. Results and Discussion showed that water stress had significantly effect on grain yield, 1000 seed weight, seed number per panicle and caused to decrement of them. Genotypes were significantly different for all traits, indicating high variability among them. The interaction between water stress and genotype did not show a significant difference about 1000 seed weight, other traits which mentioned above showed a significant difference in this aspect. The results of correlations between the studied traits showed that in normal conditions (without stress), plant height, number of seeds per panicle, Brix of stem sugar, free leaf proline content, biological yield and harvest index could be used to improve seed yield. In terms of drought stress, stem sugar, plant height, canopy temperature, free leaf proline content had the highest correlation with yield and its components. Conclusions In general, physiological traits due to their low cost could be used as good indicators in water stress investigations and provide more comprehensive information as compared with morphological traits.