JOURNAL OF AGRICULTURE
Year:2005 | Volume:7 | Issue:2|Papers Count:8

Citrus brown snail (Caucasotachea lencoranea) is known as an important pest of the citrus orchards in northern Iran. Abundance of this snail was investigated in two orchards in each of 10 localities (Mahdasht Sari, Baharestan Sari, Gahemshar, Babol, Nashtarood, Noshahr, Chalus, Ramsar, Tonekabon and Salmanshar) of the province through the monthly sampling in 2003-2004. Analysis of data indicated that the snail population abundance was in relation with the amount of rainfall. The maximum population (33.1±7.4) recorded in Ramsar locality with an annual rainfall of 1196mm while the minimum was in Baharestan Sari locality (16.2±4.5) with 798mm rainfall. The population of snail was observed with two peaks in May and October, whereas the least snail activities were recorded in February. To determine the damage of snail on leaves and fruits of the citrus (mandarin, Onsho variety) three methods of chemical (Carbaryl WP 85% - 30kg/ha), mechanical (application of PVC tube placed at base of trunks of citrus trees) and integrated control (application of PVC tube placed at base of trunks of citrus trees and the Carbaryl) were conducted in a completely randomized design (CRD) experiment with four treatments and six replications. The damage to leaves and fruits was recorded as 16.9 (±2), 8.8 (±1) for chemical; 25.8 (±3.5), 16.5 (±2) for mechanical and 13.3 (±1.5), 6 (±0.8) percent for integrated control respectively. The method of combination of PVC tubes and Carbaryl recommended for control of C. lencoranea in citrus orchards of the norther provinces of Iran.

Effects of five seeding rates (350, 425, 500, 575 and 650 seeds per m2) on four wheat cultivars (Kavir, Mahdavi, Shiraz and Roshan) were studied under salinity stress, during 2000-2001 crop seasons in Roodasht Agricultural Research Station, Esfahan. A factorial experiment based on randomized complete block design with three replications was used. Plants were irrigated with saline water (with EC=12ds/m) throughout the growing season. Two years combined analysis of variance showed that seeding rate had significant effect on grain yield, number of spikes per m2, thousand kernel weights, biomass and harvest index. However, the effects on plant height and number of grains per spike were not significant. Cultivars were significantly different in all studied traits. Increase in seed rate up to 500 seeds per m2 caused increase in grain yield, but seed rates more than 500 seeds per m2 did not cause more increase in grain yield. Therefore, 500 seeds per m2 that produced an average of 2890kg/ha of grain yield, was the suitable seed rate under the conditions of this experiment. Increase in seed rate also caused increase in number of spikes per m2 and biomass, but decrease in thousand kernel weight and harvest index. Throughout the studied seed rate range, there was linear relationship between seed rate and grain yield.

The effect of drought stress on yield and components of three varieties of autumnal rapeseed in the south eastern region of Isfahan, utilizing four irrigation regimes (i.e. No irrigation from flowering stage on, No irrigation from the podding stage on, No irrigation from grain filling stage on, and a normal irrigation regime after 80mm evaporation from class A evaporation tube) were studied. An arrangement of split plot in the form of randomized complete blocks in three replications was carried out during the cultivation season of 2003-2004. Drought stress from flowering stage on had deleterious effects on the yield of oil, oil performance, seed yield and its components, the number of pods in plant, number of seeds in pod, the weight of a thousand seeds, yield of seed, yield of oil and oil performance for the control group were 81.5, 23.3, 3.5 grams 2730, 1332 kilogram in hectare and %52.11 respectively. The same variables were 46.7, 17.8, 2.7 grams, 2206, 1098 kilogram in hectar and percentage 47.89 in treatment of irrigation from the flowering stage onwards. The results showed that rapeseed can have acceptable yield with the least available water, but in case of optimum irrigation, it can have high production.

The selection of high yielding varieties with good stability is an important objective in rice breeding programs. The grain yield of eight rice lines with a check (Nemat) were compared on six locations of Gilan and Mazandaran provinces during two years, using RCBD with four replications. Combined analysis of variance showed that the effect of variety and year x location x variety interaction were significant. Nine stability analysis methods were used in this research. Line No. 7 with environmental variance method and Line No. 1 with four stability methods (such as coefficient of variability of environment, wricke's equivalence, Shukla's stability variance and coefficient of determination) were most stable lines. The line No. 5 based on within location variance and within location C.V. parameters and Line No. 4 using coefficient of regression of mean yield on environmental index and variance of deviation from linear regression, were known as the most stable lines. Consequently, lines No. 7, 1, 5 and 4 were the most stable ones using different methods. In this research, Lines No. 4, 1 and 5 were selected because of high yield and Stability: However, because of the desired grain quality and morphological traits, line No. 4 was released as a new rice variety (Kadus) by the Agricultural Research and Education Organization in 2004.

In order to evaluation of rice stem borer's damage (Chilo suppressalis Walker), on rice cultivars an experiment was carried out by two factors, (three cultivars and five spraying times), in completed randomized block design an factorial sampling was conducted on the hills infested to dead hearts (D.h), whiteheads (W.h) and yield loss. Five hills were randomly selected from each plot and evaluated. The effects of variety and spraying times on different variables (except yield variables) were significant (p£0.01). The percentage of D.h and W.h at the first year was higher than other years. Also, the D.h, W.h and yield loss on Tarom-mahali cultivar was higher than others (p£0.05). The means of percentage D.h and W.h, 1.34, 2.49 were estimated, in the three years, respectively. Also, yield loss was estimated 12.20kg/hec. Compare with chek treatment. Correlation coefficient between D.h and yield -0.37 and W.h with yield were -0.35 (p£0.01). Tarom-mahali cuItivar was more sensitive to rice stem borer's damage than Khazar and Nemat cultivars.

Walnut is one of the important products in Kerman province and Baft town is the main area of walnut orchards. So the technical, allocative and economical efficiency of walnut farmers computed assign the degree of farmer's success in the optimum allocation of their resources. At first the proper production function was estimated, and then stochastic frontier production and technical, efficiency was estimated. Using principle of Duality, stochastic frontier cost functions were computed from stochastic frontier production function and economical efficiency was computed. Allocative efficiency was estimated with regard to economical and technical efficiency. The results show that average technical, allocative and economical efficiency in Baft are 62, 67 and 41 percent respectively.

This experiment was conducted using a Randomized Complete Block Design with Three replications with 10 barley. Cultivars in Dryland Research Station of Northern Khorasan (Shirvan) in 2004-2005 growing season. Results indicated that there was significant differences among the lines in terms of the stand percentage, days to emergence, days to heading, days to maturity, plant height, number of spikes per m2, number of seeds per spike, 1000 seed-weight and grain yield. By mean of expected mean squares, genotypic and environmental variances were calculated. The heritability of traits was estimated. In addition, correlation coefficients were calculated and path analysis was done, Days to heading, days to maturity and 1000 grain-weight had the high level of heritability. Because of the path analysis, number of seeds per spike had the direct effect on the grain yield. The direct effect of 100 grain-weight on the grain yield was considered to be reduced most probably due to indirect and negative effect of number of seeds per spike.