پديد آورندگان :
احمدوند، گودرز نويسنده دانشكده كشاورزي- دانشگاه بوعلي سينا- همدان , , حاجي نيا، سميه نويسنده دانشكده كشاورزي، دانشگاه بوعلي‌سينا همدان ,
كليدواژه :
تنفس خاك , نسبت برابري زمين , شاخص‌هاي رقابت , شاخص‌هاي تنوع
چكيده فارسي :
كشت مخلوط مي‌تواند به عنوان يكي از راه‌هاي افزايش عملكرد و پايداري توليد در واحد سطح مطرح باشد. به منظور بررسي اثر كشت مخلوط جايگزيني سويا (Glycine max L.) و ارزن (Panicum miliaceum L.) بر خصوصيات زراعي، تنوع علف‌هاي هرز و فعاليت زيستي خاك، آزمايشي در مزرعه پژوهشي دانشكده كشاورزي دانشگاه بوعلي‌سينا در سال زراعي 1393، در قالب طرح بلوك‌هاي كامل تصادفي با سه تكرار اجرا شد. تيمارهاي آزمايشي شامل پنج الگوي كشت مخلوط جايگزيني (25 درصد ارزن + 75 درصد سويا (75S: 25M)، 50 درصد ارزن + 50 درصد سويا (50S: 50M)، 75 درصد ارزن + 25 درصد سويا (25S: 75M) و تك‌كشتي سويا و ارزن) بودند. نتايج نشان داد كه بيشترين عملكرد دانه در تك‌كشتي سويا و ارزن به ترتيب با 8/219 و 9/171 گرم بر مترمربع، حاصل شد. كشت مخلوط باعث كاهش حداكثر شاخص سطح برگ و افزايش ميزان كلروفيل برگ سويا و ارزن گرديد. بيشترين تعداد غلاف در بوته و تعداد دانه در بوته سويا و بيشترين تعداد خوشه در بوته ارزن در تيمار50S: 50M به دست آمد. ميزان تنفس خاك به طور متوسط در تيمارهاي كشت مخلوط به ترتيب چهار و هشت درصد بيشتر از تك‌كشتي سويا و ارزن بود. الگوهاي كاشت 50S: 50M و 25S: 75M در كاهش تراكم و تنوع علف‌هاي هرز موفق‌تر از تك‌كشتي سويا بودند. ارزيابي نسبت برابري زمين نشان‌دهنده برتري تمام نسبت‌هاي كشت مخلوط سويا و ارزن بر تك‌كشتي آن‌ها بود و تيمار 50S: 50M بيشترين نسبت برابري زمين (20/1) را به خود اختصاص داد. سويا و ارزن در نسبت‌هاي مختلف كشت مخلوط، افت واقعي عملكرد نداشتند. محاسبه ضريب غالبيت نشان داد كه ارزن از غالبيت بيشتري نسبت به سويا برخودار بود.
چكيده لاتين :
Introduction
Intercropping is a multiple cropping practices involve growing two or more crops together. The most common goal of intercropping is to produce a greater yield on a given piece of land by making use of resources that would otherwise not be utilized by a single crop. Intercropping is one of the ways that causes more stability and increases protection and security in ecological farming systems. Intercropping is an agronomic practice that lubricity movement towards ecological agronomic system, increases the efficiency of resources (Mushagalusa et al., 2008) and yield stability. Intercropping is a sustainable practice used in many developed and developing countries and an essential element of agricultural sustainability. Many intercropping systems have proved to be better than sole crops in terms of yield because intercropping makes better use of agricultural resources and reduces interference of weeds. Muhammad et al. (2008) reported that intercropping of millet (Pennisetum glaucum) and cowpea (Vigna unguiculata) is the most predominant cropping system in the Sudan and Sahelian zones of West Africa. Millet is the staple diet while cowpea serves as a source of vegetable protein. Considering the importance of intercropping towards sustainable agriculture this study aimed to determine the best combination of soybean and millet in mixed cropping to optimal use of available resources with minimum crops competing with each other.
Materials and methods
In order to study the effects of soybean (Glycine max L.) and millet (Panicum miliaceum L.) replacement intercropping on agronomic traits and weed species diversity, an experiment was conducted at the Research Station of Agricultural Faculty, of Bu-Ali Sina University, in 2014. The experiment was carried out as a randomized complete block design with three replications. The replacement intercropping series consisted of monoculture of soybean, monoculture of millet, 75% soybean+ 25% millet, 50% soybean+ 50% millet and 25% soybean+ 75% millet.
Weed diversity was calculated using Shannon- Weiner diversity index (Equation 1).
Equation (1) H= - , Pi=
Where N is the number of individuals, ni is the number of individuals related species i and S is number of species.
Biological and grain yield were determined at the end of growing season. Before harvesting, plant height, LAI max, total chlorophyll, number of pods per plants, number of soybean seeds per plant, number of millet panicles per plant and 100 seed weights were measured in 5 randomly selected plants. Analysis of variance (ANOVA) and Duncan’s multiple range test (DMRT) were performed.
Land Equivalent Ratio (LER), Aggressiveness and Actual Yield Loss (AYL) were calculated as follows (Dhima et al., 2007).
Equation (2) LER=
Equation (3) A soybean= - A millet = -
Equation (4) AYLsoybean= AYLmillet=
AYL= AYLsoybean+ AYLmillet
Where Ysm and Yss are the grain yields of intercropped and sole soybean, and Yms and Ymm are the grain yields of intercropped and sole millet, respectively. Zsm and Zms are the mixing ratio of soybean and millet, respectively.
Results and discussion
The results showed that the highest seed yield of 219.8 and 171.9 g.m-2 belonged to monoculture of soybean and monoculture of millet, respectively. Intercropping reduced maximum leaf area index of soybean and millet but leaf chlorophyll content of soybean and millet were increased. The highest number of pods per plant, number of seeds per plant of soybean and panicle number per plant of millet were obtained in 50S:50M ratio. Mean soil respiration rate in intercropping treatments was 4% and 8 % higher than that of monoculture of soybean and millet, respectively. Tavassoli et al. (2010) in a millet and common bean intercropping system, showed that grain yields of intercropped millet and common bean were signi?cantly higher than those of millet and common bean in the corresponding sole cropping.
Intercropping patterns of 50S:50M and 25S:75M were successful in reducing weed plant density and diversity in comparison with soybean sole cropping.
For all intercropping treatments, land equivalent ratio (LER) was more than one. Maximum value of LER (2.20) was achieved in 50S:50M intercropping. Soybean and millet intercropping at different levels of replacement did not have actual yield loss. Calculating the aggressiveness showed that millet was more dominate than soybean. The maximum relative crowding coefficient of soybean was observed in 75S:25M, however that of millet was obtained in 25S:75M and 50S:50M intercropping indicating that millet is more competitor than soybean.
Conclusion
Land utilization indices such as land equivalent ratio, relative crowding coefficient and aggressiveness indicated that intercropping of soybean and millet in comparison to sole cropping, increased economic usage of land in different mixed proportions. According to above mentioned indices the best proportion of soybean and millet intercropping was 50:50. Aggressiveness index of components showed that millet was more dominant than soybean.
