فصلنامه پژوهش های تولید گیاهی
سال هجدهم شماره 3 (پاییز 1390)

The effects of irrigation methods, various levels of water and nitrogen fertilizer on quality of cotton were studied at Hashemabad Cotton Research Station of Gorgan in 2008. The experiment was conducted in split-split plot design with three replications. Irrigation methods of Furrow and Sprinkler were main plots, various levels of water of 0%, 33%, 66%, 100% and 133% were subplots plots and various levels of nitrogen fertilizer of 0%, 33%, 66%, 100% and 133% were sub-sub. The results showed that the effect of irrigation methods were significant on Fiber length, Uniform rate, Strength value and Elasticity (P<0/01). Generally, the fiber quality of cotton was better on irrigation methods of Sprinkler than Furrow. Levels of irrigation water significantly affected on the entire fiber quality of cotton except the Elasticity. It was found that the highest Uniform rate, Strength value and Micronaire were obtained in treatments 66%, 100% and 133% of irrigation water. The effect of levels of nitrogen showed significant difference on Elasticity (P<0/05) but was insignificant on Fiber length, Uniform rate, Strength value and Micronaire. The results revealed that the highest Elasticity was obtained in treatment 33% of nitrogen fertilizer. According to the results of this investigation, irrigation methods of Sprinkler and treatment 66% of irrigation water were recommended for reaching the best quality of cotton.

In order to study the effect of methanol on growth and yield of Virginia tobacco varieties Cocker 347, an experiment was carried out through a factorial experiment in Randomized complete block design with 4 replications and 18 treatments. First Treatment was spraying time which includes 3 levels, sprayed in the morning (8-10 hours) and noon (12-14 hours) and evening (17-19 hours) and the second treatment was methanol consumption values that include 6 levels of consumption values 0, 10, 20, 30, 40 and 50 percent. Methanol sprayed at 3 times during the growing season, respectively, in the rapid growth of transplant, budding and 30 days after budding of tobacco plants. Tobacco was harvested in 3 fold. The obtained results of the data analysis showed that interaction of two factors had significantly effect on the phosphorus, potassium and nitrogen values as well as RWC at 1 percent level. Leaf width was significant in different values of sprayed methanol at 5 percent level but leaf length was significant in values of sprayed methanol at 1 percent and fresh weight and stem diameter were not significant. According to the result can be concluded that methanol improved qualitative yield of tobacco but not affected Quantitative yield of tobacco.

In order to study the role of Phytophthora species associated with greenhouse cucumber root and crown rot, diseased sampled were collected in Southern Kohgiluyeh and Boyerahmad province. Pieces of infected root and crown of cucumber were washed with tap water blotted dry and plated on CMA supplemented with delvocid (10 ppm pimarcin), ampicillin (250 ppm), rifampicin (10 ppm) and PCNB (150 ppm). 40 isolates recoverd from various parts in Southern Kohgiluyeh and Boyerahmad province. Colonies on the selective medium based on morphological characters produced and temperature requirement, the pathogen were identified as Ph. capsici and Ph. drechsleri. Seventeen isolates were identified as Ph. capsici and 23 isolates were identified as Ph. drechsleri. The reaction of crown and root of 2-week-old greenhouse cucumber cultivars, Mehr, Bahman, Fadia, Close, Negin, Katrina and Cina to virulent isolates of Ph. capsici and Ph. drechsleri was evaluated under greenhouse conditions. The inoculum was obtained on vermiculitehemp seed extract and positioned around either crown or root systems. Percent dead seedlings and crown and root colonization were evaluated. Comparative percent dead seedlings and crown colonization showed that Mehr and Cina were the most and the least susceptible cultivar in reaction to Ph. drechsleri, also Close and Fadia were the most and the least susceptible cultivar in reaction to Ph. capsici. Comparative percent root colonization showed that Close, Katrina, Mehr and Negin cultivars were not significantly different in reaction to Ph. drechsleri. Cina cultivar was the least susceptible in reaction to Ph. drechsleri, Also Close and Cina cultivars were the most susceptible and Fadia cultivar was the least susceptible in reaction to Ph. capsici.

The field experiment was conducted to study the effect of soil moisture tension and potassium on growth and quantitative and qualitative characteristics of Thomson navel orange on Citrumelo rootstock in Kotra Citrus research station in ten years (1998-2009). The experiment was designed for four replications in Randomized Complete Blocks with factorial treatment structure. The factors consisted of four levels irrigation (at 20, 40 and 60 Kpa of soil moisture tension and no irrigation) and four levels of potassium (0, 50, 100 and 150 gr multiplied by tree age). Potassium was mixed with soil and was applied under trees every year. Thomson navel orange (Citrus, sinensis (L.) osbeck) trees were irrigated by Micro jet irrigation system. According to the results, irrigation increased trunk diameter, plant height and canopy diameter and volume, yield, the number of fruits and TSS/TA. Potassium treatments increased soil exchangeable potassium, foliar K, fruit diameter, weight, peel thickness, acidity and total soluble solids and the ratio of peel thickness to fruit diameter. But, TSS/TA was decreased affected by K levels. Moreover, it did not affect plant growth parameters. Regarding yield and the number of fruits, interaction effects between potassium and irrigation rates were significant.

Application of Salicylic acid (SA) as a phytohormone has been increased due to resistance to stresses such as drought. The main goal of this experiment was to evaluate the effects of SA on morphological and physiological characteristics of cucumber seedlings under drought stress. For this purpose a factorial trial based on completely randomized design was conducted with 5 levels of SA (0 (control), 0.25, 0.5, 0.75 and 1 mM) and 2 levels of drought stress, daily irrigation (control) and stopping irrigation for 6 days with 3 replications. SA was used as seed soaking for 24 hr. Drought stress was also applied in 3-4 leave stage. The results showed that SA increased chlorophyll index and leaf area by 27 and 139 percent in comparison to control, respectively. In contrast, stomatal conductance and electrolyte leakage decreased with SA application. Use of SA increased stem diameter, height, leaf number, shoot and root dry weight and biomass by 31, 65, 60, 100, 180 and 96 percent in comparison to control, respectively. Leaf number, leaf area and shoot dry weight decreased under drought stress, while increased with SA application. The interactions between SA concentrations and drought stress for the measured traits such as chlorophyll index, stomatal conductance, stem diameter, height, root dry weight and biomass, was not statistically significant.

Salicylic acid play an important role in plants physiological processes. In this research the effect of Salicylic Acid on induction of somatic embryogenesis and plant pigments synthesis in the phloem and petiole explants of carrot in the B5 medium was investigated. We added treatments with 0, 0.5, 1.5, 2 and 3 mM to culture medium by experimental base on the randomized design to investigate the effect of salicylic acid on somatic embryogenesis. Result showed that somatic embryogenesis in 0.5 mM treatment was more than other treatments and the higher concentration (1.5, 2, 3 Mm) reduced somatic embryogenesis. Also the effect of salicylic acid on chlorophyll, Anthocyanin, caratonoid synthesis of explants at realization phasein culture medium was studied. The maximum amount of Caratonoid, Chlorophyll and Anthocyanin was observed at 0.5 mM that was significant between treatments (P<0.01). By more than 0.5 mM concentration, both pigment synthesis and embryogenesis were decreased. Compression among embryogenesis of different carrot explants showed that embryogenesis in petiole explants was more than phloem. Therefore, it could be concluded that probably salycilic acid have different physiological effect at different concentration.

Decreasing water loss and increasing the irrigation times are basic methods to develop agriculture, success in natural recourse projects, minimize the stress to planted bushes in natural fields and increase the productivity of soil and water sources. The use of super absorbent is one of these strategies to achieve these goals. The main purpose of this research was to study the effect of super absorbent on increasing the irrigation period and rate of the growth of rose bushes. Randomized complete block design in natural field for two factors (super absorbent in 4 levels 0, 40, 90 and 140 gr. and irrigation period in 4 levels 6, 10, 14 and 18 days) with 3 replications were considered. The results of research showed that the impact of super absorbent in increasing the irrigation and various parameters of growth in Rose are significant. In qualitative parameters, 40 and 90 gr. levels of super absorbent had a positive effect on number of main branch parameters; however, it had no significant effect on total number of branches and number of flowers. Regarding irrigation factor, 6 and 10 day levels in number of main branch and total number of branches parameters had a significant difference with the other levels. Increasing the irrigation periods and decreasing the water availability for plants led to reduction of the flowers. Consequently, a 10-day level of irrigation with different levels of super absorbent in the number of flowers had a significant difference with the other levels. The plants buds production were various in any months.