كليدواژه :
ماده آلي , تنش خشكي , محلول پاشي , تعداد برگ , عملكرد دانه
چكيده فارسي :
به‌منظور بررسي تاثير اسيد هيوميك تحت شرايط تنش خشكي بر برخي خصوصيات موفولوژيكي، عملكرد دانه و عملكرد روغن گلرنگ رقم محلي اصفهان، آزمايشي به صورت كرت‌هاي خرد شده در قالب طرح پايه بلوك كامل تصادفي در سه تكرار انجام گرفت. فاكتور اصلي اين آزمايش شامل چهار سطح مختلف تنش خشكي (آبياري پس از 50، 80، 130 و 180 ميليمتر تبخير آب از تشتك تبخير كلاس A) و فاكتور فرعي شامل محلول پاشي اسيد هيوميك (به ميزان صفر، 1، 3 و 6 ليتر در هكتار) بود. صفات مورد ارزيابي در اين آزمايش شامل ارتفاع بوته، تعداد شاخه فرعي در بوته، قطر ساقه، تعداد برگ در بوته، عملكرد دانه و عملكرد روغن بود. تنش خشكي و محلول پاشي اسيد هيوميك به صورت معني داري بر صفات ذكر شده اثرگذار بودند. بر اساس نتايج حاصل از مقايسات ميانگين، تنش خشكي سبب كاهش معنيدار و محلول پاشي اسيد هيوميك نيز سبب افزايش معنيدار صفات ذكر شده گرديدند. بيشترين عملكرد دانه و روغن به ترتيب 1687 و 393/7 كيلوگرم در هكتار در تيمار آبياري پس از 50 ميليمتر تبخير به دست آمد. حداكثر ميزان محلول پاشي اسيد هيوميك 6 ليتر در هكتار بود كه سبب افزايش عملكرد دانه (9درصد) و عملكرد روغن (20 درصد) نسبت به تيمار شاهد گرديد. بر اساس نتايج حاصل از آزمايش و به دليل مشاهده اثرات مثبت محلول پاشي اسيد هيوميك روي گياه گلرنگ، توصيه ميگردد در صورت احتمال بروز تنش خشكي در طول دوره رشد گياه، به خصوصيات مثبت اين ماده آلي جهت افزايش رشد رويشي و زايشي در گياه گلرنگ توجه بيشتري معطوف گردد.
چكيده لاتين :
Introduction: Oil crops contain proteins in addition to fatty acids and comprise a major food requirement in the world after cereals (Roodposhti et al., 2012). Water deficiency is one of the most important challenges to agricultural production in Iran. This stress factor causes early flowering, accelerates maturity growth , shortens growth stages, reduces leaf area index, and thus reduces the absorption of light by plant. In recent years, the lack of use of organic fertilizers have led to a significant decline in the organic matter content of Iranian soils, causing environmental problems and soil nutrient imbalances. One of the important issues in ecological agriculture is the use of organic matter. An important advantage of humic acid can be its ability to chelate different elements such as sodium, potassium, magnesium, zinc etc in order to overcome the deficiency of nutrients (Ghorbani et al, 2010). Due to the importance of safflower in terms of its high tolerance against adverse environmental conditions e.g. drought srress and also the lack of research on the application of humic acid as an organic compound, the results of this work would have implications for the possibility of expanding cultivation area of safflower and oil production. Materials and Methods: To investigate the effect of different levels of humic acid on morphological characteristics as well as seed and oil yields of safflower (Isfahan local cultivar) under different drought stress treatments, an experiment was conducted at research farm of Shahrekord university during the growing season of 2012. The experiment was split plot based on in a completely randomized block design with three replications. The main factors included irrigation after 50 (control), 80, 130 and 180 mm evaporation from class A pan and the sub factors consisted of four levels of humic acid spraying (0 (control), 1, 3, and 6 litr/ha). Drought stress treatments were applied after flowering stage till the end of growth period and humic acid was sprayed after flowering stage. The measured traits included plant height, number of branch per plant, stem diameter, leaf number per plant, grain yield and oil yield. Results and Discussion: Plant height and number of branches per plant were significantly decreased under water stress treatment compared to control. The highest plant height and the greatest number of branches per plant were obtained at the highest application rate of humic acid solution. Humic acid increases the nutrient absorption ability of plants by influencing the metabolism of plant cells and chelating nutrient compounds, which can result in increased plant growth and height (Nardi et al., 2002). Stem diameter and leaf number per plant showed a significant decrease with increasing the intensity of drought stress. The reduced number of leaves per plant may be attributable to accelerated plant aging and eventually leaf loss. By increasing the amount of humic acid spraying, stem diameter and number of leaves per plant were enhanced. This could be due to the increased accumulation of dry matter and increased absorption of nutrients by the plant Grain yield under drought stress treatments significantly decreased compared to control treatment. This observation could be attributed to the water stress experienced by the plant at different stages of growth, which led to a decline in its physiological activities such as seed formation and filling and thereby a reduction 2018in grain yield. Humic acid spraying exhibited a significant increase in safflower grain yield. This is due to the increased availability of nutrients for the plant under humic acid treatment. Considering the fact that oil yield is a function of oil percentage and grain yield and also the increased stress intensity was associated with a significant reduction in safflower grain yield, it seems that in this experiment, the most important effective factor influencing oil yield was grain yield.Conclusion: Imposition of drought stress reduced all the plant yield and growth characteristic. However, spraying of humic acid significantly increased all the measured traits. The increased plant height and a parallel rise in number of branches, stem diameter and number of leaves per plant under humic acid treatments, especially in the treatment of 6 litr/ha, resulted in the enhanced plant vegetative growth.
