Y. Raei, K. Ghasemi Golezani, A. Javanshir, H. Aliari, A. Mohammadi,
Volume 12, Issue 45 (fall 2008)
Abstract
Concerning the effects of increasing the species number on the maintenance of ecological stability and agricultural ecosystems sustainability, two field studies were conducted in 2002 and 2003 to evaluate the effects of plant population densities on soybean and sorghum intercropping at the Research Center, the Faculty of Agriculture, Tabriz University, Tabriz, Iran. Cultural pattern was an additive series. The factorial set of treatments was arranged within a randomized complete block design with three replications. The first factor comprised soybean densities of 20, 30, 40, and 50 plants/m2, and the second factor consisted of sorghum densities of 0, 4, 8, and 12 plants/m2. The results indicated that both soybean and sorghum yields were significantly affected by soybean and sorghum densities. Soybean yield increased as density increased up to 40 plants/m2, and then decreased with increasing soybean density from 40 to 50 plants/m2. With increasing soybean density, sorghum yield was decreased. Sorghum and soybean yields, respectively, increased and decreased as sorghum density increased. On the other hand, Soybean and sorghum densities of 20:4 (1.6) and 50:12 (0.8) had the highest and the lowest LER (Land Equivalent Ratio), respectively. It was, therefore, concluded that intercropping of Soybean and sorghum, is more advantageous, compared to their pure cultivation in the same conditions.
F. Heidari, S. Zehtab-Salmasi, A. Javanshir, H. Aliari, M. R. Dadpour,
Volume 12, Issue 45 (fall 2008)
Abstract
In order to examine the effects of plant density on the morohological traits, yield and essential oil of peppermint, an experiment was conduced in Agricultural College of Tabriz University during 2005 and 2006. The treatments included four plant density levels ( 8,12 ,16,20 plants.m-2) with three replications. The treatments were based on a split plot design in time and result analysis of compound variance was done during two years. The two years’ results of the compound variance showed that the plant density affected the fresh yield, dry yield, the bush essential oil percentage and the essential oil yield, but it had no effect on the bush height and the leaf’s essential oil percentage. In the second year, the maximum fresh yield, dry yield, bush height, the bush essential oil percentage, and the essential oil yield were obtained. In the second year, the maximum essential oil yield in the density of 20 plant/m2 was 21.15 li.ha-1.
