M. Niknejad Kazempour, H. Pedramfar, S. A. Elahinia,
Volume 6, Issue 4 (winter 2003)
Abstract
Antagonistic fungi Trichoderma harzianum (T1, from bean fields in Ahwaz, T2, from rice fields in Rasht), T. viride (T3 from bean fields in Shahriar, T4 from the collection in Plant Pest and Disease Institute, Tehran), Gliocladium virens (from bean fields in Kamal Abad, Karaj) and some fungicides (Benomyl, Carbendazim, Carboxin-Thiram, edifenphos and Zineb) were used to control sheath blight of rice incited by Rhizoctonia solani in vitro and under greenhouse conditions. The experiment was carried out in a completely randomized design with 12 treatments and four replications on Khazar rice cultivar in a soil infected by R. solani under greenhouse conditions. The results showed that the antagonistic fungi reduce sheath blight by 19.8 (T1), 21.5 (T2), 27.5 (T3), 19.6 (T4) and 18.5 (G1) percent. The antagonistic fungi in order of efficacy were T2>T3>T1>T4>G1. Benomyl, Carbendazim, Carboxin-thiram, Edifenphos and Zineb reduced disease by 32.5, 21.5, 12.8, 9.5 and 0 percent, respectively. Statistical analysis of data indicated that there existed no significant differences between T1, T3, T4, and G1 and Carbendazim fungicide to control disease however, the isolate T2 was as effective as Benomyl but Zineb had no effect on sheath blight.
K Noohi, F Sahraeian, M Pedram, A Sedaghat Kerdar,
Volume 12, Issue 46 (1-2009)
Abstract
Dates of start and end of frost based on minimum shelter temperature equal to or less than 0°C were studied in Zanjan, Ghazvin and Tehran during 1961-2000. The cause of these frosts was determined by weather parameter values at observation hours and the aid of synoptic maps. Frost series based upon last spring or first fall advection are defined and found to be random and normally distributed. The "potential growing season", defined as the interval between spring last and first fall advection frosts, is found to be 29 days in Zanjan, 23 days in Ghazvin and 10 days in Tehran longer than the "growing season" defined by the interval from last spring to first fall occurrences of minimum shelter temperature of 0°C or less. The numbers of radiation frosts in the interval between first radiation frosts in fall or last radiation frost in spring and related advection frost were counted and found that this parameter is greater in Zanjan. Frostless days between the first two fall frosts and last two spring frosts show that the lengthening of spring season with one night protection is possible for 4 days in Zanjan, 6 in Gazvin and 4 in Tehran, providing that first fall and spring last frost is radiation. Results of this study permit estimating the practicality of frost protection for specialized crops in the area of study.
