JWSS - Journal of Water and Soil Science

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Canola (Brassica napus) is one of the important oil seed crops cultivated in many parts of Iran. One of the main problems of seed production of canola is pollination and fertilization of flowers. Insects are the major pollinators. In order to study the fauna of insect pollinators of 3 cultivars of canola including Talaye, Okapi and S.L.M. and the difference between the attractiveness of these cultivars to insects during the flowering period, insects were collected by sweeping net and identified. Their abundance was determined at different periods of time during a day. Results showed that insect pollinators belonged to five orders and 18 families. The most abundant pollinators were Hymenopterous insects specialy honey bees (Apis mellifera) which were about 50%. Irrespective of Apis mellifera, the most abundant insects captured belonged to Diptera. Three Dipterous insects, Bibio hortulanus, Metasyrphus corollae and Platypalpus sp. were collected and identified. During the flowering period (March to mid April) in Isfahan, honey bees were more abundant in the warmer hours of the day, mostly noon and afternoon, but were less active in the early hours of the day, morning, because of cold weather and low nectar production. Honey bees were more active than other pollinators on Talaye at 9 a.m. and on Okapi at mid-day, noon, and during afternoon. Results also showed that insect pollinators could increase seed yield by 53%.

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Cultivation of a second crop in paddy fields of Guilan province is a strategy for optimum use of land, supporting family economy and increasing oil-seed production. However, this is impeded under high rainfall and waterlogging conditions. To enhance second-crop cultivation in paddy fields, surface drainage is inevitable. The surface drainage practices should be performed with minimum costs, least time span and least variations of the land. In the present research, longitudinal surface drains were constructed with a spacing of 2, 4, 6, 8 and 10 m (depth of 20 cm), with and without 1-m lateral drains (depth of 10 cm) in Rice Research Institute, Rasht, Iran. The experiment was conducted in a complete randomized block design with three replications. Canola (Brassica napa), variety PF, was cultivated as a second crop after rice. The results showed that the effects of drain spacing on seed yield, days to maturity, number of plants per m², and also the effects of lateral drainage on seed yield, plant height, residual N, days to maturity, and number of plants per m² are significant (P<0.01). Highest yield (2493 kg/ha) was obtained from longitudinal drains 4 m apart, with lateral drainage drain spacing of 6 and 2 m had acceptable yields, too (2241 and 1817 kg/ha, respectively). For treatments without lateral drainage, 2-m drain spacing had the highest yield (1324 kg/ha). Considering all the expenses for drainage construction, it was found that net benefit of longitudinal drain spacing of 4 and 6 m was twice the costs. Since the rainfall in Nov., Dec., and Jan., 2000, was higher than the 20-year average rainfall of the same months, it was concluded that the results of this experiment may be recommended in the years with a rainfall less than the year 2000.

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Pollination and fertilization of canola flowers are the main factors of canola seed production. In order to study the effects of insect pollinators on seed quantity and quality of three chosen cultivars of canola, namly, S.L.M., Okapi and Talaye, a split plot experiment in a complete randomized block design with four replications was carried out in Isfahan region. Main plots consisted of canola cultivars, and subplots consisted of open pollination and non-pollination by insects. Results indicated that the time to seed ripening in pollinated plots was 10.5 days less than those of non-pollinated plots. Pollination by insects increased the number of pods per plant, number of seeds per pod and weight of 1000 seeds, by 14.3%, 23.5% and 10%, respectively. Grain yield also increased by 53% in pollinated plots. Pollination decreased seed moisture percentage by 3.15%, but its effect on seed oil percentage and germination percentage were not significant. Time to seed germination of plants of pollinated plots decreased three hours. Cultivars were significantly different in seed oil percentage and time to seed germination. Talaye cultivar produced the highest amount of oil (45.5%), while Okapi produced the lowest (40.8%). There were significant interactions between cultivars and pollination in terms of seed ripening, oil percentage and moisture of seeds, and the effects of pollination was different in different cultivars.

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To study the effect of salt stress on quantitative and qualitative parameters of canola (Brassica napuse. L) cultivars, and determine the possible mechanisms of salt tolerance and the best salt tolerance indices, an experiment was conducted under a rain-shelter at experimental field of university of Kerman in 2004. The experimental design was a complete randomized block (RCOD) with four replications. Treatments consisted of all combinations of different levels of three factors including variety (Kobra×Regent, Ceres and Okapi), salt types (NaCl and CaCl₂) and electrical conductivity of saline solution (0, 4, 8 and 12 dS/m). All treatments were randomly distributed in each replication. Results of the analysis of variance showed that grain yield, yield components, oil and protein contents were significantly affected by salinity (P< 0.001). All the mentioned traits reduced with increasing salinity. It was also found that there were significant differences among genotypes for the mentioned traits. Cultivar of Kobra×Regent showed the highest values of the above traits except for the oil content. Proline, protein and sugar contents were also affected significantly by salinity (P<0.001). The highest and lowest sugar concentrations and protein contents were recorded for control and 12dS/m treatments, respectively. Proline content showed a reverse response and increased with increasing salinity. Mean productivity (MP), geometric mean productivity (GMP) and stress tolerance index (STI) are suggested to be the most suitable indices in order to select genotypes of high productivity under both stress and normal conditions. Based on these results, Kobra*Regent was selected as the most tolerant cultivar.

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In order to study the effect of various amounts of nitrogen (N) and Iranian natural zeolite on the quantitative and qualitative forage yield of winter canola (Brassica napus L.) in light soil, a field experiment was conducted on research farm of Tarbiat Modares University, Tehran, during 2006-2007. Treatments were arranged in the form of RCBD with 3 replications. The experimental treatments were based on factorial various levels of zeolite (0, 3, 6 and 9 t.ha^-1) and nitrogen (90, 180 and 270 kg ha^-1) in urea form. Seeds of canola (Brassica napus L. cv. Okapi) were sown on October 2, and fresh forage was harvested at the time of silique formation (170 DAP). Results showed that the effect of N and zeolite on forage quantitative attributes including biomass, leaf and stem dry weight and leaf area index were statistically significant. In addition, forage qualitative traits including crude protein percentage and calcium percentage in plant mass were significantly affected by N and zeolite. Increasing application of N fertilizer caused increase in N leaching, and with increasing zeolite application, N leaching reduced. The interaction of two factors for all parameters was not significant. The most increasing effects on forage yield and quality were gained using 270 kg N ha^-1 in combination with 9 t. Zeolite ha^-1. More detailed studies are strongly recommended to investigate the effects of integrated application of chemical fertilizer and natural zeolite.

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Oil seed rape is an important non-cereal crop used mainly for edible oil production. Canola pods are fragile and its branches are twisted together at harvesting time. Harvesting with a conventional combine can pull off twisted branches and cause appreciable losses in the vicinity of divider at combine header. In this study, a hydraulic rotary divider was designed and developed to separate twisted pods and reduce the grain loss. The device is made up of two cylinders and a number of fingers, the cylinders rotate in opposite direction and fingers move in and out through holes on cylinder walls. The assembly was expected to separate the twisted pods and reduce grain loss. A hydraulic motor driven by combine hydraulic system was used to rotate the separating cylinders. The separating assembly was installed on righthand side of the combine harvester header. A split-plot experiment was used to evaluate the performance of the unit. Field tests were carried out at combine forward speed of 1.5 kmh-1. Variables were: cylinders rotary speed in three levels (50, 75 and 100 rpm), the number of fingers in three levels (16, 12 and 8), and the tests were conducted with and without combine reel. Two different positions of finger protrusion were also considered in field tests. The results were compared with those of a conventional combine header. The results show that the medium rotational speed (75 rpm) exhibited lowest seed loss. Furthermore, as the number of fingers increased, the seed loss tended to decrease. The seed loss also decreased in the presence of combine reel. Also, findings showed there is no significant difference between the two protrusions trajectories of fingers. A twenty percent decrease in seed loss was observed at rotary speed of 75 rpm and number of fingers of 16 in the presence of combine reel.

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In order to study the effects of salt stress and leaf feeding by ascorbic acid on antioxidant enzyme activity, proline accumulation and lipid peroxidation on leaves and roots of Brassica napus L. cvs. Okapi, an experiment was conducted as a factorial in a completely random design with three replications. Plants were exposed to salt stresses by NaCl solution (200 mM) and foliar were treated by ascorbic acid solution (25mM). Catalase, Superoxide dismutase and peroxidase activity were assayed in shoot and root. Also, malondialdehyde content and proline and chlorophyll in leaves were determined. The results showed that the activity of all antioxidant enzymes (except for SOD in roots) were increased significantly in plants under salt stress, and ascorbic acid application, as a antioxidant decreased their activity in leaves, but in roots it was not effective. Total protein content in leaves and roots decreased significantly under salinity condition. Ascorbic acid treatment increased total protein content under salt stress in both roots and shoots. Measurement of malondialdehyde content in leaves and roots showed that lipid peroxidation was increased by active oxygen species due to salt stress, and ascorbic acid reduced lipid peroxidation only in leaves. Chlorophyll content was also decreased by salinity compared to control. According to the result of present study, ascorbic acid application decreases deleterious effect of salinity.

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Canola (Brassica napus L.) as one of the oilseed crops has recently received lots of attention due to its suitable oil quality and high oil percentage. To evaluate the effect of water deficit stress on canola genotypes with regard to yield, drought tolerance quantitative indices and identify drought tolerant genotypes, an experiment was conducted in research farm of seed and plant improvement Institute (Karaj) using completely randomized block design with four replications, and 25 genotypes under two stress and non stress conditions. Genotypes were evaluated regarding drought tolerance. Drought tolerance quantitative indices include MP, GMP, STI, SSI and TOL. Result of variance analysis showed significant differences among genotypes as regards all indices and seed yield of genotypes in both conditions at 1% probability level. MP, GMP and STI indices were selected as the best indices for selection of tolerant genotypes in regard to analysis of correlation between seed yield in two stress and non stress conditions and drought tolerance indices. Results indicated that Genotype Vectra was the best genotype, because of its proper mean yield in both stress and non stress conditions. Multivariate biplot figure display showed that MP, GMP and STI indices had high correlation coefficient with each other, and tolerant genotypes were located near tolerance indices. Also results of three dimensional scatter plot and cluster analysis indicated that genotypes Modena, Jura, Eshydromel, Vectra, Dante, Zarfam, Esbetty and Olano were tolerant to drought stress, and genotypes Olpop, GKHelena, RG4504 and Olphi were sensitive genotypes.

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Gray mold, caused by Botrytis cinerea, is a serious disease of cut rose flowers (Rosa hybrida L.) in Iran. In order to elucidate the effects of different potassium and calcium levels in nutrient solution on susceptibility of cut rose flowers to gray mold, this experiment was carried out as factorial design in a randomized complete block with four replications at Safi Abad Agricultural Research center in 2008 for one year. In this experiment, rose plants were grown and subjected to three levels of potassium (1.0, 5.0 and 10.0 mM) in combination with two levels of calcium (1.6 and 4.8 mM) under hydroponic condition. Rose flowers from two consecutive harvesting periods were sprayed with the conidial suspension (104 spore/ml) of B. cinerea isolate. At the end of experiment the disease severity was recorded and analyzed. The results indicated that application of 10.0 mM K in the nutrient solution led to increasing rose disease severity to gray mold (30.4 % day-1) compared to 1.0 mM (24.8 % day-1) and 5.0 mM (26.2 % day-1) of K levels (P< 0.01). The increased susceptibility was associated with a decreased concentration of Ca in the rose petals. Correlation analysis revealed that susceptibility of rose flowers to gray mold significantly increased with K to sum cations ratio in the nutrient solution (r = 0.94*). The increase of Ca supply from 1.6 to 4.8 mM resulted in decline of disease severity from 29.6 to 24.6 % day-1 (P< 0.01). Therefore, balanced application of potassium and calcium (5.0 and 4.8 mM, respectively) is recommendable for preventing antagonistic effects between them and reducing of rose gray mold intensity under hydroponic conditions.

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In order to assess the effect of drought stress and various levels of potassium on solutes accumulation and chlorophyll of canola and Indian mustard, a field experiment was conducted in a factorial design based on randomized complete block design with three replications including three irrigation regimes (I1=irrigation after 50% depletion of soil water(control),I2 =irrigation after 70% water depletion and I3 =irrigation after 90% water depletion), two species (Hyola 401 hybrid of canola and landrace cultivar of mustard) and three levels of potassium fertilizer (K1=0 ,K2=150 and K3= 250 kg.ha-1 K2SO4 ) at Agricultural and Natural Resources Research Center of Sistan in 2008-2009 cropping season. Water stress increased proline and soluble carbohydrate accumulation in the leaves of Brassica sp. In non stressed condition (control) in different growth stages, proline was lower than water-stressed plants and Leaf proline content decreased significantly after irrigation. Mustard landrace showed higher capability for accumulating assimilates such as proline, soluble carbohydrates and potassium than hybrid Hyola 401. Water stress decreased the amount of chlorophyll a, b and total leaf chlorophyll, but Potassium application caused an increase in the mentioned parameters. The highest content of chlorophyll pigments was observed at flowering stage. Potassium application caused a decrease in proline and an increase in soluble carbohydrates concentration in the leaf under water stress condition. There was a negative correlation between grain yield and proline content and soluble carbohydrates, but grain yield was positively correlated with chlorophyll, a, b. It was concluded that osmotic adjustment can be an important mechanism for Brassica species under water stress conditions and that organic and inorganic compounds such as proline, soluble carbohydrates and potassium play key roles in this regard.

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In recent years, simulatiom modelling of yield has been the focus of attention for many researchers. Because, while reducing adminestrative costs, it can easily provide simulation models of different situations. In this study, while a subroutine on simulation of canola was added to CRPSM model, effect of different water treatments on canola was also investigated. In this research, canola (Talaye) under 5 irrigation treatments (full irrigation treatment during the growing period, water stress treatment at the spring re-growth stage, the flowering stage and pod formation, the grain formation stage and dry land treatment) was sown in complete randomized block designs at the college of Agriculture, Shiraz University during 2007-2008, and then the model was calibrated based on available information (soil-location -plant-water). Review of statistical indicators between simulated and measured yield show high accuracy in the estimation of crop yield (R2=0.98) and soil water content. The result of model validation with independent data series also showed that the result of soil water content is desirable except in dry treatment, and the corrolation coeficient between simulated and measured crop yield (R2=0.98) was acceptable.

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Stabilizing heavy metals in polluted soils is a method to prevent them from entering plants. Clay minerals are considered good sorbents for heavy metals due to their low cost, high abundance, easy manipulation and harmlessness to the environment. The objective of this study was to investigate the potential of clay deposits containing smectites and palygorskite to sorb cadmium and to reduce its movement into canola. Two selected deposits are located in the Isfahan Province. Physical and chemical characteristics of clay deposits were determined. The clay fraction was then separated from each deposit sample. This study showed that palygorskite was the dominant clay mineral in deposit sample 1 and smectites in deposit sample 2. These clays were then used as an amendment to plant growth medium. Pot experiment was carried out with canola (Brassica napus) as a test plant with 3 replicates. Treatments included three growth media: smectite + quartz sand, palygorskite + quartz sand and pure quartz sand (control treatment) under 3 Cd concentrations: 0, 2.5 and 7.5 ppm. Results obtained from the pot experiment indicated that deposits containing smectite and palygorskite were very useful in stabilizing cadmium in polluted soils and could prevent Cd from entering plant. Smectite clay mineral could retain a higher quantity of cadmium as compared to palygorskite. Plants in pots amended with smectite had a higher growth rate as compared to those in control and palygorskite amended pots. Cadmium accumulation in plant roots was much higher than that in shoot. Furthermore, the higher Cd concentration in growth media resulted in the higher amount of Cd uptake by the plant.