جستجوی مقالات مرتبط با کلیدواژه « تنش کمبود آب » در نشریات گروه « آب و خاک »

In this study, the interactive effects of soil moisture and SS levels were investigated on alfalfa (Medicago sativa c.v Garehyounjeh) shoot and root fresh weights, water use efficiency (WUE), and concentrations of some elements in a loam soil under greenhouse conditions. A factorial experiment based on a randomized complete blocks design with three replications was conducted with two factors: soil moisture at three levels (0.81 FC–FC, 0.56–0.75 FC, and 0.35–0.50FC) and SS at four levels (0, 15, 30, and 60 g/kg soil). When 10% of the alfalfa plants flowered, the shoot and root fresh weights, concentrations of nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), sodium (Na), copper (Cu), iron (Fe), manganese (Mn), and zinc (Zn) and WUE of alfalfa plant were measured. The results showed that the main and interactive effects of SS and soil moisture on alfalfa shoot and root fresh weights, WUE, and concentrations of elements were significant (p≤0.01). The decrease in soil moisture content, decreased alfalfa shoot and root fresh weights, WUE, concentrations of Fe in the shoot and concentrations of P, Fe, and Na in the root (p≤0.05); while it increased concentrations of Cu in the root, and Cu and Zn in the shoot (p≤0.05). Effect of soil water content on concentrations of N, K, Ca, Mg, Zn, and Mn of the root depended on the level of SS. Concentrations of Mg, Fe, Zn, Cu, and Mn in the root and shoot and concentrations of P, K, and Ca in the root were increased (p≤0.05) with the use of SS and increase in its level. By increasing the SS level, shoot and root fresh weights were initially increased and then decreased (p≤0.05). Effect of SS on WUE depended on soil water content. With sufficient water supply (0.81FC–FC), WUE was increased with increment of SS level, while under water-deficit stress (0.35FC–0.50FC), application of SS up to 30 g/kg increased WUE but at the level of 60 g/kg, increase in the soil salinity reduced WUE (p≤0.05). To increase WUE and improve the nutrition and growth of alfalfa at similar conditions, 30 grams of SS per kilogram of soil may be recommended under both well-watered and water-deficit conditions. Although the use of sewage sludge had some beneficial effects in this experiment, the potential risks of heavy metals in long-term application of this organic waste should be considered and avoided.

Management of manure and chemical fertilizers application in the soil in terms of environmental impacts and performance of plants is important, especially in arid and semi-arid regions of Iran. A split plot experiment was carried out in a randomized complete block design with three replications at the research farm of Shahrekord University in 2014. Main factor was consisted of three levels of irrigation regimes including 100% (I1 or control), 75% (I2) and 50% (I3) of water requirement while 6 levels of manure application including 1) no amended fertilizer (control), 2) 25% urea fertilizer + 75% cattle manure 3) 50% urea fertilizer + 50% cattle manure 4) 75% urea fertilizer + 25% cattle manure 5) 100% urea fertilizer and 6) 100% cattle manure, were considered as subplot factor. Results showed that irrigation regime of I3 caused decreasing an contration of chlorophyll a, b and total, essential oil yield of flowering branch, leaf and stem while in caused 83 and 13.5 percent increase in the amount of carotenoids and proline compared to control, respectively. Fertilizer treatments, 25% urea fertilizer + 75% cattle manure, 50% urea fertilizer + 50% cattle manure, 75% urea fertilizer + 25% cattle manure, 100% urea fertilizer and 100% cattle manure caused significant increase in carotenoids content compared to control whereas the maximum carotenoids content with the average of 1.35 mg g-1 was obtained from the 25% urea fertilizer + 75% cattle manure treatment. A significant positive correlation was observed between chlorophyll a, b, total, essential oil percentage, essential oil yield of leaf and essential oil yield of flowering branches. Therefore, in order to obtain the maximum essential Moldavian balm under Shahrekord climatic condition, application of 50% urea + 50% cattle manure and full irrigation is recommended.

An experiment was conducted as a split plot design (with three replications) to evaluate effect of water deficit on seed germination of safflower cultivars. The main plots comprised six cultivars viz. Dizaj Hossein Beig¡ Koshaksara¡ Aghkand¡ N05¡ 917405 and 51063 and the sub main plots comprised three levels of osmotic potentials of 0¡ -0.6¡ and -1.7 bar. Results showed that stress levels affected germination percentage¡ plumule and seedling length. In addition¡ safflower cultivars had different germination percentages. Applying stress at -1.7 bar decreased plumule and seedling and ridicule lengths. Base on ability in germination under water deficit condition Dizaj Hossein Beig¡ Koshaksara¡ Aghkand are the suitable cultivar to cultivate in the water deficit conditions.

Drought and low rainfall are arising problems in recent years in many countries that limit agricultural production. An appropriate solution to overcome water deficit stress in sustainable agriculture is establishment of mycorrhizal symbiosis in plants. Mycorrhizal fungi affect plant growth by widespread activity in roots and soil. A greenhouse experiment was carried out using tomato (Lycopersicon esculentum L. cv. Behta) plants inoculated with two species of mycorrhizal fungi Glomus intraradices (Gi) and Glomus etunicatum (Ge) in a sterile soil. The experiment was factorial based on a completely randomized design with three replications. After plants establishment, three ranges of soil moisture: (0.9FC–FC) [D0] and (0.7FC-0.8FC) [D1] and (0.55FC-0.65FC) [D2] were applied to the pots. In both fungal species root mycorrhizal colonization decreased by decreasing soil moisture. Inoculation of plants with Gi and Ge increased shoot dry weight by 14.5% and 16.2%, respectively, compared to non-mycorrhizal plants but shoot dry weight declined by decreasing soil moisture. Mycorrhizal fungi significantly (P<0.01) increased leaf relative water content (RWC), leaf water potential (LWP) and stomatal conductance (gs) but these parameters were decreased by decreasing soil moisture. Mycorrhizal plants at all levels of soil moisture had more shoot P concentration than the control plants, but Ge significantly increased shoot K concentration. Thus, both P and K contents decreased by decreasing soil moisture. Based on the results, it can be concluded that the arbuscular mycorrhizal fungi can increase tomato growth and nutrient uptake under water deficit stress.

In order to study the effects of different levels of irrigation, nitrogen and plant population on yield, yield components and reserved dry matter remobilization of seed corn (SC. 704 hybrid) a research was conducted at the experimental field in Khuzestan Natural Resources and Agricultural Science University in summer, 2004. This research was made based on three split-plot field experiments, RCBD. Each of the irrigation treatments implemented separately in each experiment have been as follows: Optimum irrigation, Moderate stress and Severe stress (irrigation after drainage 50%, 75% and 100% of available water based on 70%, 60% and 50% of field capacity, respectively). In each experiment three nitrogen levels consisting of 140(N 1 ), 180 (N 2 ) and 220(N 3 ) Kg N ha-1 were applied in main plots and subplots which consisted of three plant populations (D 1 =6, D 2= 7.5 and D 3= 9 plant m-2). There were three replications for each experiment. The results of the combined analysis of variance indicated that the effect of water deficiency stress, nitrogen and plant population on grain and biological yield was significant. With increasing severity of drought stress, the grain and biological yield decreased. The maximum grain yield was estimated to be 1017.04 gm -2 which was related to optimum irrigation treatment. Grain yield reduction was mainly due to reduction of grain per ear and 1000 seed weight. The increase of nitrogen consumption caused an increase in grain yield. The positive effect of nitrogen application on grain yield considerably decreased as a result of the increased water deficiency in soil. The response of grain yield to plant population was positive. The contrary to interaction effects of irrigation and nitrogen, and irrigation, nitrogen and plant population, the interaction effects of irrigation and plant population and also nitrogen and plant population on grain yield were significant. The results indicated that the difference between different levels of irrigation in the case of dry matter remobilization rate was significant. The least and the highest remobilization rate of reserved dry matter was related to optimum irrigation and drought moderate stress treatment, respectively. The efficiency and contribution of remobilization in grain yield increased in response to increasing severity of drought stress, but these traits significantly reduced as a result of nitrogen consumption. Remobilization rate and contribution of reserved materials to grain yield in the highest density (D3) were significantly more than other densities. According to the results of this study, under drought stress conditions, the decrease of inputs consumption, in addition to the decrease of costs, will be followed by the increasing efficiency use of the resources.