AGRICULTURAL RESEARCH
Year:2007 | Volume:7 | Issue:2|Papers Count:8

In this study the effect of two strains of Bacillus subtilis alone or in combination with sodium b1tarbonate on controlling citrus green mold caused by Penicillium digitatum was investigated.Application of 108 cfu/ml of bacterial strains on artificially inoculated fruits by P. digitatum caused at last55% reduction of rotted fruits after 5 weeks storage at 20, 10 and 4oC. Integrated application of antagonistic strains with sodium bicarbonate (3% w/v) resulted in more than 67% decay reduction in 4°C and the best result, 79.26% disease reduction, was obtained by integrated use of BN strain (5 x 107 cfu/ml) with 3% sodium bicarbonate. Laboratorial assays showed that these strains inhibit pathogen spore germination and also their culture filtrate and cell-free culture are able to control of the pathogen on the surface of fruit.

Soil erosion by water is an important problem in farming lands particularly in semi-arid regions. This study was conducted to predict soil erosion based on the universal soil loss equation (USLE), find out predicting error, determine spatial variation of soil erosion and provide a soil erosion map in dry farming lands in semi-arid regions. The study was carried out in an agricultural zone with a dimension of 30Ian in south part of East Azerbaijan province from March 2005 to March 2006. In the study area, 36 dry farming lands on 9% uniform slopes that had plowed on slope direction with no cover crop on surface, were considered. Soil erosion was measured in each farming land under natural rainfall events during the study period and predicted based on the USLE by multiplying rainfall erosivity (R), soil erodibility (K) and slop length (L) factors. The rainfall erosivity factor (R) on the study area was 448.707 MJ mml ha h per year. Mean valiue of the soil erodibility factor (K) and slop length factor (L) were 0.0360 th/MJ mm and 1.519, respectively.Based on the results, annual predicted soil erosion (24.621 t/ha) averagely was 10.98 times larger than the measured value (2.888 t/ha). Effective range of the predicted soil erosion (4.5 km) also was bigger than the predicted value (2.4 km) on the study area. The predicted values of soil erosion in all places on the study area were larger than the measured values. These differences were due to estimating errors of factors affecting predicted erosion (R, K and L). The study showed that the USLE is not accurade in predicting soil erosion in semi-arid regions.

In this study antagonistic activity of Pseudomonas fluorescens UTPF-59 against Rhizoctonia solani, the causal agent of bean damping- off in vitro and in vivo was assessed. Production of secondary antifungal metabolites such as HCN, siderophore and protease by P. fluorescens UTPF- 59 in vitrowere evaluated. Results showed that in vitro, strain UTPF-59 reduced mycelial growth of R. solanimore than strain P. fluorescens CHA 0. Average of inhibition zone in strain UTPF-59 was lSmm while it was 10mm in strain CHA 0. Strain CHA 0 had more effect on control of bean damping offin vivo, disease intensity in CHA 0 for soil drenching and seed coating was 60% and 35.72%, respectively, while UTPF-59 reduced the disease by 33.34% and 14.29% in soil drenching and seed coating respectively. Strain UTPF-59 produced siderophore, HCN and protease in vivo. In strain UTPF-59 involvement of siderophore, volatile and non-volatile metabolites on inhibitory of mycelial growth of R.solani in vitro was observed. Investigation on colonization of root of bean in absence of the pathogen showed that population of both bacteria reduced by 104 cfu g -1 root as compared with primary population of thebacteria on seeds (109 cfu seed -1) after one month. In this survey, detection of phlD and phlA genes (responsible for biosynthesis of diacetylphloroglucinol) was evaluated with PCR. Both genes detected in strain UTPF-59.

Salt stress is one of the most important limited factors limiting in seed germination and plant growth. In this study, effects of sodium chloride, GA3 and benzyl adenine on seed germination of three corn single cross cultivars including 704, 700, and 647 were studied. The experiments was conducted in factorial with the layout of randomized complete block design with three replicates. sodium chloride concentration at three levels including 0, 75 and 150 millimolar sodium chloride and three levels of both GA3 and benzyl adenine including 5, 10 and 15 mg/l were used. Sodium chloride and hormone had significant effects on seed germination. Sodium chloride reduced seed germination percent, where-as hormones enhancement increased it. The highest germination percent was observed in cultivar 700 under 75 millimolar of NaCI and 15 mg/l gibberellic acid treatments. Treatment with 10 mg/l gibberellic acid produced the most seed germination percent in cultivar 704. The highest germination percent for cultivar 647 was observed in treatment with 15 mg/I gibberellic acid. Salinity enhancement reduced abnormal seedling number, root and shoot lengths and seedling fresh weight. Salinity increased seedling dry weight. Gibberellic acid had more effect on the mentioned traits than benzyl adenine except for root length. Results of this study showed that GA3 could be used to increase seed germination under salinity stress.

In the dry regions like "Southern Khorasan Province", irrigation has a great role for productivity, but, since in the use water of irrigation in these regions mainly has the solution salts, therefore, the effect of salinity on the growth of plant must be analyzed simultaneously. In order to study the effects of salinity and irrigation regimes on yield, yield components and seed protein in wheat cultivars, an experiment was conducted in 2005-2006 with three replication. The experimental design was factorial complete block split plot in which salinity with three levels (1.4, 4.5 and 9.6dS/m of irrigation water) were used as the main plot and four irrigation regimes (50, 75, 100 and 125 percent of depth of water requirement) and wheat cultivar ((Ghods & Roshan) as factorial were as sub plot. Result showed, seed yield, 1000 seed weight, biological yield, harvest index and percentage of protein were' significantly affected by salinity. But, number of spike per square meter, number of seed per spike and height of plant were not affected by salinity. Also, seed yield, biological yield, harvest index percentage of protein, 1000 seed weight and number of spike per square meter were significantly affected by deficit irrigation, but, height of plant and number of seed per spike were not significantly affected. In this experiment we found that seed yield, 1000 seed weight, height of plant, biological yield, harvest index, number of seed per spike and percentage of protein were significantly affected by cultivars, but, number of spike per square meter were not significantly affected. The interaction of salinity and deficit irrigation (S*I) had not any significant effect on each of factors of yield and component yield, so we can conclude that aggregative effect of salinity and deficit irrigation (on the decreasing of yield) is less than summation of effects of each on of them. Increasing salinity or land deficit irrigation had an increasingly effect on ' percentage of protein of grain in both cultivars of wheat, although, the effect of deficit irrigation was more than salinity effect. There was no significant difference of grain yield and number of spike/m2 in the treatments of 100% and 125% of depth of water requirement, we can say that additional irrigation more than plant requirement, (I4, 125% of depth of water requirement of plant) had not significant effect on these parameters, whereas, averages of biological yield was higher in I4, we can conclude that, increasing the applicable water (more than 100% of depth of water requirement of plant), cause increasing in vegetation growth rather than increasing of grain yield. Yield and percent of grain protein of Roshn wheat, were respectively 26% and 5% more than Ghods wheat, so that, Roshan wheat was quantitatively and qualitatively proportional to both deficit irrigation and salinity stress, more resistance than Ghods wheat, and Roshan wheat had a greater productivity.

Based on the division of international institutes, Iran is confronting with water Crisis.Agricultural sector uses more than 93 percent of supplied water in country. One of the best method to control water losses is increase of conveyance efficiency (Ec) by linings of irrigation canals with suitable construction materials according to local conditions. Different linings have various durability and conveyance efficiency under climatic and subsoil conditions. Therefore, the evaluation of different lining is necessary in various areas for the best selection. In this research, conveyance efficiency have been evaluated in customary lining of concrete and local lining of stone and unlined small irrigation canals in Hamedan- Bahar plain for two years. For this main 12 cases of lined and unlined irrigation canals were randomly selected to evaluatio in different points of this plain. The conveyance efficiency was measured in initial, medium and the end stages of growth in two year. Durability cndition of concrete linings that had been cracked was studied by coring of eight samples. According to the results, value of conveyance efficiency in lining of stone was 94.4% that with 5% probablity is more than that in lining of concrete (71.1 %) and unlined canals (66.6%). The mean compressive strength of eight cores was 61 kg/cm2 that is very less than its standard value. Because of low compressive strength, the concrete lining does not have suitable durability in cold climate of this area, so in most canals, it has been cracked and destructed that lead to very low value of ec. Based on range test, the values of EC in concrete lined and unlined canals with 1% probablity, have not significiant difference.

Surge flow irrigation is a new concept in surface irrigation methods that improves preformance efficiency and uniformity in furrow irrigation. Surge flow irrigation is only effective in the first two irrigations. Its effectiveness will be the same as continuous irrigation on the rest. In surge flow irrigation, inflow rate is kept constant. Stepwise inflow rate increment promotes wetted perimeter over which infiltration occurs. The effect of this concept is not yet known on application efficiency and irrigation uniformity. In order to compare advance phase water saving and moisture uniformity, three treatments such as continuous flow, surge flow with constant inflow rate, surge flow with stepwise flow rate were selected. Field experiments for this research were carried out in Agricultural Research Station at University of Tehran located in Karaj. Soil texture in study area is sandy clay loam. Tests were conducted two times for the first irrigation in 150 and 200 m furrows.Results indicated on the first two irrigations, the volume of water required to complete advance phase in surge flow irrigation with stepwise inflow increase, was 10 and 12 percent less, respectively, in compare to surge flow irrigation with constant inflow rate. In the meantime, soil moisture distribution also was more uniform than the surge flow irrigation with constant inflow rate.