Sh.a. Sarani, A. Sharifi Tehrani, M. Ahmadzadeh, M. Javan Nikkhah,
Volume 11, Issue 42 (1-2008)
Abstract
Two hundred fifty seven bacterial isolates were collected from colza root and rhizosphere in Golestan, Mazandaran, Guilan and Tehran provinces. Antagonistic effect of bacterial isolates on Rhizoctonia solani, the causal agent of colza damping off, was studied using dual culture method. The results showed that, 60 isolates had the ability to inhibit the growth of R. solani on PDA medium. On the basis of the biochemical, physiological and morphological tests, isolates P1, P2 and P3 were identified as Pseudomonas fluorescens. Biocontrol mechanism studies showed that isolates produced antibiotics and volatile metabolites prevented the mycelial growth of the fungus. The isolates produced some of antimicrobial metabolites including hydrogen cyanide, protease and siderophore. Isolate P3 was more effective to inhibit the growth of the fungus in-vitro. The effect of isolates on disease reduction in comparison with control was significantly different. None of the isolates were able to prevent disease occurrence completely. Isolates applied as soil treatment had a significantly higher disease control as compared to seed treatment method. Isolate P3 had considerable effect on reduction disease in the greenhouse conditions. All isolates were capable of colonizing canola roots and so increased canola growth in free-causal agent conditions.
A Mohseni, M Zibaei,
Volume 13, Issue 47 (4-2009)
Abstract
Because of the fact that alternative agricultural policies cannot be examined in a laboratory, the potential effects of policies must be analyzed before policy setting, and during or after the policy implementation using mathematical programming (MP) models. In this context, the consequences of increasing the acreage of colza at representative farm (RF) level of Namdan plain were analyzed using positive mathematical programming (PMP), which were improved to overcome normative character of optimization models. The main aim of PMP is to give as true a picture as possible of the situation and then simulate the behavior of farmers as parameters in which the object of agricultural policy intervention is shifted. Based on the results of this study, reduction in the acreage of wheat and bean and increase in the expected profit of RFs are the consequences of increasing acreage of colza. But, as variance of profit increases, the net impact of policy on the expected utility of RFs is not perfectly known. The results also indicated that the use of pesticide increases through introducing colza into a cropping pattern. The effect of policy on water use is different among RFs and they can't take this policy as a water demand management policy.
