واکنش عملکرد و اجزای عملکرد ارقام نخود دیم (Cicer Arietinum L.) به تراکم بوته و حضور علف‌های‌هرز

به منظور بررسی واکنش زیست‌توده کل علف‌های‌هرز، عملکرد و اجزای عملکرد چهار رقم نخود دیم به تراکم کاشت و تداخل علف های‌ هرز در شرایط دیم شهرستان کرمانشاه، آزمایشی در سال زراعی 94-1393 در مزرعه تحقیقاتی دانشکده کشاورزی دانشگاه رازی کرمانشاه انجام گرفت. آزمایش به صورت فاکتوریل بر پایه طرح بلوک های کامل تصادفی در سه تکرار اجرا شد. تیمارها شامل سه تراکم کاشت (31.3، 38.5 و 50 بوته در مترمربع) و چهار رقم نخود آزاد، آرمان، هاشم و عادل در دو سطح وجین و عدم وجین علف‌های‌هرز بود. به طور کلی، با افزایش تراکم کاشت همه ارقام نخود، از میزان عملکرد اقتصادی کاسته شد. در تراکم های کاشت 38.5 و 50 بوته در مترمربع، رقم آزاد به ترتیب 8.9 و 42.6 درصد، رقم آرمان به ترتیب 30.5 و 37.2 درصد، رقم هاشم به ترتیب 23.7 و 40.2 درصد و رقم عادل به ترتیب 32.9 و 36.3 درصد نسبت به تراکم کاشت 31.3 بوته در مترمربع کاهش در عملکرد اقتصادی از خود نشان دادند. رقم آزاد در تیمار وجین علف های هرز با میانگین تولید 146.4 گرم در مترمربع، بیشترین و رقم آرمان در تیمار عدم وجین علف های‌ هرز با میانگین تولید 45.2 گرم در مترمربع، کمترین عملکرد اقتصادی را تولید کردند. عدم وجین علف‌های‌ هرز به ترتیب باعث کاهش 59.1، 51.9، 61.2 و 46.3 درصدی عملکرد اقتصادی در ارقام آزاد، آرمان، هاشم و عادل شد. در مرحله اول نمونه برداری از علف های ‌هرز، بیشترین (25.7 گرم در مترمربع) و کمترین (17.7 گرم در مترمربع) زیست‌توده کل علف‌های‌هرز به ترتیب در تراکم کاشت 31.3 و 38.5 بوته در مترمربع مشاهده شد. درمرحله دوم نمونه برداری از علف های‌ هرز، بیشترین (60.0 گرم در مترمربع) و کمترین (42.8 گرم در مترمربع) زیست‌توده کل علف‌های‌هرز به ترتیب در تراکم کاشت 31.3 و 50 بوته در مترمربع مشاهده شد. در مرحله دوم نمونه برداری از علف های ‌هرز، بیشترین (54.7 گرم در مترمربع) و کمترین (40.8 گرم در مترمربع) زیست‌توده کل علف‌های ‌هرز به ترتیب در ارقام نخود هاشم و عادل مشاهده شد. در مجموع نتایج این آزمایش نشان داد که ارقام آزاد و هاشم با تراکم بوته کم (31.3 بوته در مترمربع) و با کنترل کامل علف های هرز برای کاشت به صورت دیم در منطقه مورد بررسی توصیه می شوند و راهبرد کاهش خسارت علف های هرز از طریق افزایش تراکم بوته، کارایی مناسبی ندارد.

Response of yield and yield compounds of rain-fed chickpea cultivars (Cicer arietinum L.) to plant density and weed interference

IntroductionThe most important principle in the rainfed cropping system is to maintain and optimal use of soil moisture. In this regard, selecting the appropriate cultivar and planting density is one of the most important management decisions. The open canopy structure, short stature, limited leaf area, and the slow growth rate of chickpea is responsible for its poor competitive ability against weeds. In rainfed cropping systems, weeds can also play an important role in soil moisture depletion and can aggravate drought stress on crop at the end of the growing season. Among the weed control cropping methods, it is possible to select a competitive cultivar and/or increased planting density. After introducing a new cultivar from rainfed chickpea, researchers have always compared it with older cultivars in terms of competitive ability against weeds. So far, there has been no comparative study of competitive ability or tolerance of a new rainfed chickpea cultivar, Adel, against weeds with older cultivars. Consequently, the effect of planting density of this new rainfed chickpea cultivar on the response of weeds was not investigated. Therefore, the aim of this study was to investigate the interaction of this new and old cultivars and planting density on weeds damage under rainfed conditions in Kermanshah. Materials and MethodsThis research was carried out at the research farm of the faculty of agriculture and natural resources of Razi University, Kermanshah, during 20132014 growing season. Wheat was planted in the same farm during the previous growing season. During the experiment, the total rainfall was 85.51 mm. After preparing the land to plots of 6 × 2 m2, the chickpea cultivars were manually planted with the distance of 40 cm on each row on 5 February 2013. The experiment was a factorial (3 crop densities × 4 chickpea cultivars × 2 weed interferences) in a completely randomized block design with three replications. Planting densities were 31.3, 38.5, and 50.0 plants m2. Chickpea cultivars were Arman (FLIP9096C), Azad (FLIP9393C), Adel (FLIP9966C), and Hashem (FLIP8448C). The factor of weed interference was at two levels of weeding and unweeding. The crop was harvested on 28 June 2014 to evaluate yield and yield components. The samplings of weeds were performed to determine the total biomass using a 1 m2 quadrate on 20 May and 12 June 2014, which were coincident with the flowering time and physiological maturity of chickpea, respectively.  Results and DiscussionIn general, the economic yield was decreased by increasing the plant density in all chickpea cultivars. The planting densities of 38.5 and 50.0 plants m2 reduced the economic yield up to 8.9 and 42.6% in Azad cultivar, 30.5 and 37.2% in Arman cultivar, 23.7 and 40.2% in Hashem cultivar and 32.9 and 36.3% in Adel cultivar compared to planting densities of 31.3 plants m2, respectively. Azad cultivar produced the highest economic yield (146.4 g m2) under weeded condition, while the lowest economic yield (45.2 g m2) belonged to Arman cultivar under unweeded condition. The presence of weeds resulted in a reduction of 59.1, 51.9, 61.2, and 46.3%, in the economic yield of Azad, Arman, Hashem, and Adel cultivars, respectively. During the first weeds sampling, the highest (25.7 g m2) and the lowest (17.7 g m2) weed biomass were observed at planting density of 31.3 and 38.5 plants m2, respectively whereas during the second weeds sampling, the highest (60.0 g.m2) and the lowest (42.8 g. m2) weed biomass were observed at 31.3 and 50.0 plants m2, respectively. Moreover, during the second sampling of weeds, the highest (54.7 g m2) and the lowest (40.8 g m2) weed biomass were observed at the plots of Hashem and Adel cultivars, respectively. ConclusionIn this research, the planting density of 31.3 plants m2 was optimal planting density for all four chickpea cultivars. It seems that the increase of planting density to control weeds in rainfed chickpea cropping system is an unsuitable technique. Therefore, it is necessary to consider other techniques to control weeds in rainfed chickpea cropping systems. An interesting observation in this study was that, although the economic yield of Adel cultivar was lower, the lower biomass of weeds in the plots of this cultivar was observed compared to other cultivars. This observation can be related to allelopathic compounds produced by Adel cultivar which is costly for the crop itself and has reduced its yield.