بررسي شاخص‌هاي رشد و مراحل فنولوژيك كنجد (Sesamum indicum L.) در شرايط استفاده از منابع تغذيه‌اي زيستي و شيميايي

Growth and Phenology Analysis of Sesame (Sesamum indicum L.) under Biological and Chemical Nutritional Sources

به‌منظور ارزیابی اثر كودهای مختلف زیستی و شیمیایی بر شاخص‌های رشد و مراحل فنولوژیكی كنجد آزمایشی در قالب طرح پایه بلوك‌های كامل تصادفی با 10 تیمار و سه تكرار انجام شد. تیمارهای آزمایش شامل كودهای زیستی نیتروكسین (Ni)، بیوفسفر (BP)، بیوسولفور (PS)، تركیب زیستی دوگانه Ni+BP و سه‌گانه Ni+BP+BS، كودهای شیمیایی اوره (U)، سوپرفسفات تریپل (P)، تركیب شیمیایی دوگانه U+P و سه‌گانه U+P به‌علاوه گوگرد (S) عنصری (U+P+S) و شاهد (بدون مصرف كود) بود. نتایج این آزمایش نشان‌دهنده برتری تیمارهای تركیبی كودهای زیستی و شیمیایی نسبت كاربرد تكی آن كودها بود. بر این اساس تیمارهای تركیبی دوگانه و سه‌گانه زیستی و شیمیایی بهترین روند شاخص‌های رشدی تأثیرگذار بر تولید ماده خشك (شاخص سطح برگ و سرعت رشد محصول) را نسبت به شاهد داشتند كه منجر به تجمع بیشتر ماده خشك در این تیمارها گردید. بالاترین نقطه اوج سرعت آسیمیلاسیون خالص نیز در تیمار دوگانه زیستی مشاهده شد. هرچند در این آزمایش در تیمارهای مختلف از نظر شاخص‌های رشدی تفاوت‌هایی مشاهده شد و با وجودی كه سبز شدن گیاهچه‌ها در تیمارهای زیستی زودتر اتفاق افتاد، اما تحلیل‌های آماری نشان داد كه مراحل مختلف فنولوژیكی كنجد از هیچ‌كدام از تیمارهای این آزمایش تأثیر معنی‌داری نپذیرفت. بنابراین از یافته‌های این پژوهش چنین نتیجه‌گیری می‌شود كه كاربرد تركیبی كودهای زیستی و كودهای شیمیایی در بهبود شرایط رشدی گیاه اثر قابل توجهی داشته و تغییری در فنولوژی گیاه به‌وجود نمی‌آورند. نهایتاً با توجه به مزایای استفاده از كودهای زیستی، استفاده از تركیب كودهای زیستی به‌عنوان بهترین گزینه برای تولید كنجد پیشنهاد می‌گردد.

Introduction Nowadays technological innovations, the use of chemical inputs, development of methods and etc., help agriculture to produce food for human. However, some problems such as growth in fertilizer prices and environmental pollution has drawn attentions to sustainable agriculture. Sesame as the oldest known oil-seeded plant by mankind has ranked #9 among 30 important oil seeds. Therefore cultivation of this valuable plant should be done based on ecological principles and inputs. Growth and phenological aspects of sesame affecting by bio-fertilizers is less known. Therefore, the aim of this experiment was to evaluate the growth and phenology of sesame by application of various biological and chemical nutritional sources. Materials and Methods This experiment was conducted in randomized complete block design (RCBD) with 3 replications and 10 treatments including Nitroxin® (Ni), Biophosphor® (BP), Biosulfur® (BS; with recommended amount of elemental sulfur), double mixture of Ni+BP, triple mixture of Ni+BP+BS, Urea (U), triple super phosphate (P), double mixture of U+P, triple mixture of U+P plus the used amount sulfur in BS, and control. Sampling was conducted every 7 days and growth indexes including, leaf area index (LAI), total dry matter (TDM), crop growth rate (CGR), relative growth rate (RGR), net assimilation rate (NAR) were studied during growth life of the crop. Phenological stages were recorded then GDD was calculated for different phenological stages. Statistical analysis and drawing of figures were performed using Minitab and MS Excel. Results and Discussion A. Growth Indexes: Changes in LAI, TDM, CGR, RGR, and RGR under all treatments were almost similar. during the early days of growing, LAI increased gradually and then it rose sharply after production of more leaves by the plant in most of the treatment about 35 days after sowing. After the flowering stage, by lowering of increase in LAI, all of the treatments reached to their maximum LAI and then decreased. Control and BS had minimum LAI (2.42 and 2.54) among all treatments. LAI of U+P+S and U+P were highest LAI (3.42 and 3.32 respectively) and after it, Ni+BP+BS (3.03) and Ni+BP (3.01), urea (2.98), Nitroxin (2.85), Biophosphor (2.75), triple superphosphate (2.78) were placed respectively. The highest dry matter accumulation occurred in plots that meet higher LAI, resulting in a higher potential for the production and accumulation of dry matter. So, the highest dry matter accumulation was recorded in U+P+S and U+P, and then Ni+BP+PS and Ni+BP and urea. Due to the development of leaves and roots, CGR increased and then reached to its highest amount after 52 to 70 days from the sowing. Then, about 100 days from sowing, CGR decreased and this trend continued to the end of plant life. Application of Nitroxin and Biophosphor increased CGR of sesame, but it did not affect CGR of Biosulfur treatment. The double and triple mixture of biofertilizers and chemical fertilizers increased the growth of sesame in comparison to their sole application. Numeral amount of RGR was between 0 to 1 that describes the amount of increase in plant dry matter weight in order to its previous dry matter’s weight among a time period. In all treatments, NAR at the beginning of the growing season due to low levels of leaves and photosynthesis were low. Gradually in the middle of the growing season, NAR increased, along with the increased growth of plants and their LAI. Because of some reason remobilization and aging of the leaves and reduction of the efficiency of photosynthesis, NAR has an intense reduction. All the treatments had higher NAR comparing to control. B. Phenological Stages: Statistical analysis of data showed that the effect of treatments on phenological stages was not significant. But seeds in the treatments of biofertilizers grew 3 days earlier in average. It has been proven that farm managerial decisions that cause faster growing of plants (even one day), can be effective in competitions of crops versus the weeds. Conclusions Based on the results, it can be concluded that although nutrition resources affected the sesame growth indexes, they had no effect on phenological stages of sesame.