فصلنامه پژوهشهای زراعی در حاشیه کویر
سال هفتم شماره 4 (زمستان 1389)

To study the effects of phosphorus fertilizer on biomass and some morphological characteristics of six species of annual medic, a pot experiment was conducted using a factorial employing randomized complete block design with three replications. Six medic species were considered as factor A and five levels of phosphorus as factor B. Different morphological characteristics and forage yield in different treatments were assessed during the growth period. The results showed that significant differences among the medics species for dry forage weight in different phosphorus levels. The effect of phosphorus levels on plant height and number of internodes and interaction effects of medics species and phosphorus levels were also significant. Species Medicago polymorpha and M. trancatula produced more dry forage yield with higher levels of phosphorus fertilizer. Application of 0.9 g/kg soil of phosphorus produced the highest dry forage. According to the results of this experiment, in rainfed cultivation areas of cereals where due to consumption of phosphorus fertilizers the lands are rich of phosphorus, cultivation of annual medic species in rotation with cereals can be recommended.

Present study was conducted to evaluate the role of super absorbent polymer use in oilseed rape crop (Brassica napus L.) cultivars under drought stress. In order to study the effect of super absorbent polymer on oil content and its composition in oil rape seed varieties, this research was carried out in research farm of Seed and Plant Improvement Institute in 2009 in Karaj-Iran. A field experiment was conducted as Randomized Complete Block Design with Factorial split-plot arrangement with three replications. Irrigation strategy had two levels (irrigation after evaporation 80% of water from class A Pan as control and drought stress started from flowering stage to physiological maturity) and application of super absorbent was allotted to at two levels (non-application of super absorbent as control and application of super absorbent with 7% concentration) as main plots. Cultivars (Rgs003 (V1), Sarigol (V2), Option500 (V3), Hyola 401 (V4), Hyola330 (V5) and Hyola420 (V6) was allotted to sub plots). Results showed that drought stress conditions decreased oil percentage, Palmitic acid and Linoleic acid but its increased Stearic acid. Our results suggested that in drought stress conditions, application of super absorbent polymer could reserve different amounts of water in itself and so increases the soil ability of water storing and increasing vegetative period leads to increase of oil quality by decrease of saturate fatty acids and increase of unsaturated fatty acids. With attention to increased, oil percentage, oil quality and decreasing plant water requirement, it seems that this material is economically acceptable.

In this study tolerance of 36 oriental tobacco genotypes to aphid was evaluated under field conditions at Tirtash Research & Education Center Tirtash,Iran during 2006. The evaluation method consisted of natural infestation of host plant and abundance of aphids on the tip of leaf. Based on the means of abundance in peak of aphid population, genotypes Basma 12-2 and Basma Mahalades were ranked as moderately. To study the relationship between tolerance of tobacco genotypes and morphological and chemical traits, percent of sugar, nicotine, total nitrogen, resin, height of plant, length, width, number, colour and thickness of leaves were measured. Results showed significant differences among the genotypes regarding these traits. Analysis of correlations revealed that genotypes having more percent of sugar in leaves and less thickness leaf were relatively more tolerant

In order to evaluate the response of rapeseed cultivars to moisture regimes and correlation analysis in different growth stages, an experiment was conducted in 2006-2007 at Seed and Plant Improvement Institute of Karaj, Iran. The experimental design was split plot on basis of randomized block design with 3 replications. Four irrigation levels consisted of irrigation after 80 mm evaporation from class “A” pan as control, stopping the irrigation in stem elongation stage, stopping the irrigation in flowering stage and stopping the irrigation in podding stage were applied in main plots, and subplots consisted of split application of cultivars at four levels (Opera, Modena, Zarfam and Okapi). Results showed that number of pod per plant, pod length, 1000-seed weight, oil seed content and branch number per plant were reduced significantly in response to water deficit stress. Seed yield decreased more than biological yield and resulted in decrease of harvest index. Correlation coefficient analysis revealed that harvest index (r=0.72**), 1000-seed weight (r=0.29*), biological yield (r=0.38**) and oil seed content (r=0.3*) had positive and significant correlation with seed yield. Flowering and podding are most sensitive stages to water stress. Stopping the irrigation from flowering stage also had undesirable effect on grain yield and its components. Among cultivars, Opera produced more seed yield (4053 kg/ha) than the others in normal irrigation and under water deficit stress conditions, Zarfam had maximum seed yield in stem elongation (3569 kg/ha), flowering (2135 kg/ha) and podding stages (2476 kg/ha). Based on the results of this research it can be concluded that Zarfam had better capability to tolerate drought stress and could produce greater seed yield in stress conditions.

To study the effects of plant density and N-fertilizer on seed vigour of milk thistle (Silybum marianum) an experiment was conducted in 2005 at research station of Hammand Absard. The harvested seeds were stored in a suitable place for a year, then they were used for measuring of seed vigour, mean daily germination, mean time of germination, seedling vigour index (calculated by seedling dry weight and seedling length), electrical conductivity, cold test and accelerated ageing test. The results indicated that with increasing the mother plants growth achieved by decreasing the plant density and increasing of N-fertilizer, the seeds vigour increased. It had also a positive effect on mean daily germination, mean time of germination, seedling vigour index and decreasing the electrical conductivity of seeds. There was a positive correlation between increasing of the seed power against cold, heat and water stress and improving of the mothers plant growth.

This research was conducted to evaluate the effects of silicon of application and nitrogen rates on yield and yield components of rice in two irrigation systems. Field experiment was conducted as split-split plot laid out in a randomized complete block design with four replications in Sari, in 2007. Three factors: irrigation system at two levels (continuous flooding and alternative irrigation system) as main plots and nitrogen rates in four levels (N0, N46, N92, and N138 kg ha-1) as sub plots and silicon application in two levels (Si0 and Si500 Kg ha-1) as sub-sub plots. Results showed that there were significant differences on biological yield, tiller number and fertile tiller number among irrigation systems at 1% probability level but, was not significant difference between grain yield. Biological yield in flooding was higher than deficit irrigation. Grain and straw yield significantly differed between nitrogen rates. N0 and N138 had minimum and maximum grain yield with 4306 and 6128 Kg ha-1. There were significant difference on grain yield, straw yield and HI at 1% probability level and filled and blank spikelet number per hill at 5% probability level. N138 and N0 had maximum and minimum tiller number with 15 and 9.63, respectively. Si500 and Si0 had maximum and minimum grain yield with 5090 and 5355 Kg ha-1, respectively. Spike number per m2, tiller number and fertile tiller number, spikelet number per hill and filled and unfilled spikelet number were affected by nitrogen rates. Fertile tiller percentage in N0 and N138 were maximum and minimum, respectively. Fertile tiller percentage obtained from Si0 and Si500 were 93.2% and 91.5%, respectively. Si0 and Si500 had the maximum and minimum spikelet number, respectively. Increase of nitrogen rates reduced 1000-grain weight.

To evaluate the effects of foliar application of methanol and drought stress on growth and yield of sugar beet a, an experiment was conducted at research farm of Islamic azad university, Karaj branch (mahdasht) in 2008-2009 using completely randomized block design with factorial treatments in three replication. Six aqueous solutions of methanol 0(control), 7%, 14%, 21%, 28% and 35%(v/v) each containing 0.2% glycine, and two levels of irrigation, normal (irrigation after 40%deleption of available water) and drought stress (irrigation after 70%deleption of available water) were factors of the experiment. Methanol solutions were sprayed on foliar parts of sugar beet plants three time in two week intervals 80day after planting. Different characteristics related to growth and yield in different treatments were recorded six time during the growth period. The results showed that application of methanol increased total dry matter in different treatment up to 40 percent at 130 days aftar planting compared to the control. Leaf area index (LAI) was also increased significantly. Total dry matter (TDW) in normal irrigation condition showed an increase of 350gr/m2 130 days after planting. Maximum leaf area index (LAI) was recorded at 110 days after planting in normal condition. Application of 21% (v/v) methanol had significant effects in root yield, leaf yield and white sugar yield. Normal irrigation increased these characteristics significantly.

To study the effects of soilless culture on optimizing the concentration of nutrient elements in leafy vegetables, an experiment was conducted in Ramsar, Iran, during summer 2007 using a randomized complete block design with three replication. Five common leafy vegetables including sweet basil, savory, garden cress, Allium sp and parsley were grown in experiment desing containing sand without any nutritious elements and were irrigated with water containing Papadopoulos nutritious solution. When the plants were sufficiently grown, fifteen samples from each vegetables were selected randomly, and macro and micro elements were measured in them. Based on the results of analysis of variance on data collected, leafy vegetables differed significantly in concentration of N (at %5 level) and K, Fe, Zn and B (at %1 level) but they were not significantly different in concentration of P, Mn and Cu. Means comparison showed that the concentration of measured elements were in permissible and desirable levels in leafy vegetables and consumption of them will not cause signal to appear malnutrition or effects of aggregation of thse elements in consumers. According to the obtained results it can be concluded that development and promotion of soilless culture of leafy vegetables could undoubtedly improve the well nutrition of consumers.