نوع مقاله : مقاله پژوهشی
نویسندگان
1 گروه علوم کشاورزی، واحد مشهد، دانشگاه آزاد اسلامی، مشهد، ایران
2 گروه علوم کشاورزی، دانشکده مهندسی، دانشگاه آزاد اسلامی واحد مشهد، مشهد ایران
3 بخش تحقیقات علوم زراعی باغی، مرکز تحقیات و آموزش کشاورزی و منابع طبیعی خراسان رضوی، سازمان تحقیقات، ‏آموزش و ترویج کشاورزی، م،
چکیده
کلیدواژهها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
In order to study the effect of deficit irrigation on RWC, proline concentration, antioxidant enzymes content, chlorophyll concentration and forage yield of five clover species, a field experiment was conducted during the cropping season 2019-2020. The experimental design was split plots arranged based on randomized complete blocks design (RCBD) with three replications. Deficit irrigation at three levels (0 (Full irrigation), 20 and 40% less than the irrigation requirement) were considered as main plots and five clover species (Trifolium resupinatum ، T. alexandrium ، T. lapaceaum ، T. echinatum و T. diffusum) were allocated as sub plots.The results showed by increasing deficit irrigation up to 40%, proline concentration increased by 93% and the content of antioxidant enzymes catalase, peroxidase and superoxide dismutase increased by 12, 98 and 83% respectively. However, RWC, yield of fresh and dry fodder decreased by 22, 24 and 29% respectively. The highest RWC, chlorophyll concentration and content of antioxidant enzymes were observed without significant difference in T. resupinatum and T. alexandrium species. The interaction effect of two factors (deficit irrigation × species) showed by increasing deficit irrigation, fresh and dry forage yield of all five species decreased significantly. In all three levels of deficit irrigation, the highest yield of fresh (20.39, 18.81 and 13.94 t/h) and dry forage (4.59, 4.25 and 3.06 t/h) were obtained in T. resupinatum species. In general, the results showed that all 5 species do not have the required stability under stress conditions. Therefore, deficit irrigation for the proposed species will be justified only if a 20 and 40 percent irrigation water reduction is more beneficial than the yield reduction.
کلیدواژهها [English]
Effect of deficit irrigation on Relative Water Content (RWC), Proline concentration, antioxidant enzymes content, chlorophyll concentration and forage yield of five clover species
EXTENDED ABSTRACT
Iran, with an average annual rainfall of 240 mm, which is equivalent to one third of the world average annual rainfall, is considered to be a dry and semi-arid region. For this reason, Iran is facing a serious limitation of water resources. One of the most important strategies for optimal use of available water in the conditions of limited water resources is the deficit irrigation method. The aim of deficit irrigation is to increase the water use efficiency and to maximize the yield per each unit of water consumption. But deficit irrigation can affect the growth and development of the plant by causing drought stress. Drought stress and the dehydration of plant tissues causes a decrease in photosynthesis, hormonal changes such as an increase in abscisic acid, and oxidative stress and it's negative effects. To reduce the effects of drought stress, plants use various mechanisms such as closing the stomata and controlling water loss, strengthening the antioxidant system to deal with the destructive effects of reactive oxygen species, and increasing compatible osmolytes to osmotic adjustment.
Considering the importance of clovers in crop rotation and their place in fodder production, it is necessary to determine the ecological needs and investigate various aspects of it’s crop management. For this reason, in this study, the effects of drought stress caused by deficit irrigation on the quantitative and qualitative characteristics of 5 species of clover were studied.
This research in order to study the effect of deficit irrigation on relative water content, proline concentration, antioxidant enzymes content, chlorophyll concentration and forage yield of five clover was carried out under the climatic conditions of Mashhad, during the cropping season 2019-2020.The experiment was conducted in split plots arranged based on randomized complete blocks design with three replications. Deficit irrigation at three levels (0 (Full irrigation), 20 and 40% less than the irrigation requirement) were considered as main plots and five clover species (Trifolium resupinatum ، T. alexandrium ، T. lapaceaum ، T. echinatum و T. diffusum) were allocated as sub plots. In each treatment, variables such as relative water content, proline content, antioxidant enzymes (Catalase, peroxidase and Superoxide dismutase) chlorophyll a and b and fresh and dry forage yield were measured.
The results showed that the effect of deficit irrigation on all traits (except chlorophyll a and b), the effect of species on all traits and the interaction effect of two factors on the content of proline, peroxidase and fresh and dry forage yield were significant. With the increase of deficit irrigation, the relative water content and fresh and dry forage yield decreased. But the content of proline and catalase, peroxidase and superoxide dismutase enzymes increased. Evaluation of interaction between two factors showed that the with the increase of low irrigation, the yield of fresh and dry forage yield decreased in all 5 species. But the highest amount of fresh and dry forage yield were obtained in all three levels of deficit irrigation in the species of Trifolium resupinatum.
In general, the results showed that all 5 species do not have the required stability under stress conditions. Therefore, deficit irrigation for the proposed species will be justified only if a 20 and 40 percent irrigation water reduction is more beneficial than the yield reduction.