ارزیابی سودمندی کشت مخلوط سه‌گانه ذرت (Zea mays L.)، لوبیا‌چیتی (Phaseolus vulgaris L.) و کدوی تخمهکاغذی (Cucurbita pepo L.)

In order to evaluate the benefits of maize, pinto bean and naked pumpkin triple cropping, an experiment was carried out as a randomized complete block design with three replications at Faculty of Agricultural Science, University of Guilan, Rasht, Iran in 2012. The treatments consisted of maize, pinto bean and naked pumpkin sole cropping (100, 75 and 50% of conventional densities), maize – pinto bean and maize – pumpkin double cropping (100-100%, 75-75% and 50-50%), and maize-pinto bean-pumpkin triple cropping (100-100-100%, 75-75-75% and 50-50-50%). The highest and lowest forage fresh weights were obtained in triple cropping system with high density and sole cropping systems with low density, respectively. In double cropping systems, the maize-pumpkin out-yielded the maize-pinto bean in terms of fresh weight. The relative crowding coefficient, competitive ratio and aggressivity of maize in double cropping of maize-pinto bean and naked pumpkin in double cropping of maize-naked pumpkin were dominant. In triple cropping systems, while maize and naked pumpkin were comparable, but both of the latter crops were dominant over pinto bean. Land Equivalent Ratio (LER) for double and triple cropping was greater than one, revealing the profitability of double and triple cropping systems on sole cropping. According to the LER, the cropping systems can be ranked as follows: triple cropping > double cropping maize/pinto bean > double cropping maize/pumpkin