Journal of Plant Ecophysiology
Volume:2 Issue: 4, 2010

Salinity is an important limiting factor of growth and yield of crops. Conversely, salicylic acid (SA) is known as a plant hormone for decreasing the adverse effects of salinity stress. Therefore, in the current study the effect of SA pre-treatment of seeds (at three levels of 0, 0.1 and 0.5 mmol) on germination and growth of seedlings of alfalfa was investigated under salinity stress conditions (at three levels of 0, 10 and 15 ds.m-1) in the laboratory of Jihad-e-Agriculture High Educational Complex, Scientific-Practical University of Kerman, Kerman, Iran as a factorial experiment based on a randomized complete block design with three replications. Salinity stress decreased germination percentage, seed vigor index and growth parameters (stem length, radicle length, and seedling fresh and dry weight). This decrease was stronger under 15 ds.m-1 salinity stress than the other salinity levels. On the other hand, SA pre-treatment improved growth and resulted in higher resistance of plants to salinity, so that it increased germination percentage, seed vigor index and growth parameters of the seedlings. Also, salinity intensified electrolyte leakage, while SA decreased it and this decrease was stronger at SA concentration of 0.5 mmol. It can be concluded that pre-treatment with SA induced adaptive responses in alfalfa plant under salinity stress and consequently, encouraged protective reactions in biotic membranes which improved the growth of alfalfa seedlings.

In order to examine the effects of different levels of N fertilization and plant density on the yield of field mustard (Brassica campestris) cv. Goldrush, a study was carried out in Qazvin, Iran in 2009-2010 as a split-plot experiment based on a randomized complete block design with three replications. The main plot was pure N from urea source at four levels of 0, 50, 100 and 150 kg.ha-1 and the sub-plot was plant density at four levels of 60, 80, 100 and 120 plants.m-2. Statistical analysis showed that different levels of plant density and N significantly affected the number of siliques per plant, the number of seeds per silique, 1000-seed weight, seed yield, oil yield, biological yield and harvest index. The increase in N level increased all these traits at all treatments. Also, higher densities up to 100 plants.m-2 led to higher values of all traits. The density of 120 plants.m-2 resulted in the lowest value of all traits at all treatments. In total, the densities of 80 and 100 plants.m-2 and the application of 100 kg N.ha-1 were considerably superior and produced the highest seed yield (3491 kg.ha-1) and oil yield (1084 kg.ha-1). Furthermore, the highest seed oil content (37.97%) was obtained at the density of 100 plants.ha-1 treated with 150 kg N.ha-1.

The objective of the current study was to study the effect of drought stress and organic nutrition on quantity and quality of lemon balm (Melissa officinalis). Lemon balm is a perennial herbaceous herb which is extensively used in pharmaceutics and food industries. Given that province of Kerman, Iran, is an arid region, the current study was so important because of the limitation of water resources. The study was carried out in Kerman, Iran in 2008 as a split-plot experiment based on a randomized complete block design with three replications. The main plots included drought stress at two levels of stress and no-stress and the sub-plots included organic fertilization treatments at five levels of three types of green manure (vetch, alfalfa, clover) and decomposed (cattle) manure with the amount of 30 t.ha-1. The drought stress was created by changing irrigation interval. The measured traits included plant height, single-plant leaf number, single-plant stem and leaf dry and fresh weight, single-plant fresh and dry weight, leaf:stem ratio, leaf length and width and finally, leaf area. The data were analyzed and the means were compared by Duncan’s multiple range test. The results showed that the effect of green manures was significant on leaf number, leaf fresh weight, stem fresh weight, leaf dry weight, plant fresh weight and leaf area. Plant yield had the highest correlation with leaf number, plant height, plant fresh weight and stem fresh weight. The highest plant yield was obtained under cattle manure and alfalfa green manure treatment. The effect of drought stress was significant on treatments.

Knowledge of the effect of fertilizer on yield, dry matter and oil content of Jatropha (Jatropha curcas) and determination of the best combination of fertilizers are important. The purpose of this study was to determine the effects of nitrogen, phosphorus and potassium on dry matter, grain yield and seed oil and fatty acids contents in Jatropha. An experiment was done as a 2×2×2 factorial arranged in a randomized complete block design three replications. The experimental factors were Nitrogen fertilizer (N) at two levels (N1=0, N2=70 kg/ha), Phosphorus (P) at two levels (P1=0, P2=120 kg/ha) and potassium (K) at two levels (K1=0, K2=150 kg/ha). At the end of the experiment, dry matter, grain yield and seed fatty acids were determined. The highest value of dry matter (617.3 g/m2) and oil (358 g/m2) were obtained from N2K2P2 treatment. Principle Component Analysis (PCA) showed that 43% of the variance was related to N, 38% to P and 19% to potassium. Multiple regression analysis was conducted to determine the regression coefficient between yield (Y) and fertilizers (N,P,K). The model developed was Y= 422.1+1.36X1+0.63X2+0.271X3 where X1=nitrogen, X2=phosphorus and X3=potassium. This shows that N, P and K fertilizers had the highest contribution in the variation of yield, respectively.

In order to study the effect of water deficit stress and manure application on seed yield and morphological traits of desert indianwheat (Plantago ovata Forssk.), a split-plot experiment was conducted in greenhouse of Islamic Azad University, Jiroft Branch, Iran in spring 2009 based on a Randomized Complete Block Design with three replications. The treatment of water deficit was the main plot at three levels of irrigation when soil moisture reached 75, 50 and 25% of field capacity (mild, moderate and severe stress, respectively). Also, manure application formed the sub-plot at five levels of 0, 10, 20, 30 and 40 t/ha. The results showed that water deficit significantly affected seed yield and other related traits including plant height, spike length, spike number per plant, root dry weight and hay yield except 1000-seed weight. The treatment of manure did not significantly affect plant height and 1000-seed weight. The treatment of mild water deficit stress with the application of 20 t manure/ha produced the highest seed yield (232.3 kg/ha) which showed no significant difference with the treatment of moderate water deficit stress at the same manure level. Thus, the application of 20 t manure/ha is recommended in the cultivation of desert indianwheat in climatic conditions of Jiroft, Iran, when there is a relative water deficiency.

In order to determine the concentrations of nutrients of leaf and yield of hazelnut as affected by Fe- and Zn-enriched vermicompost, an experiment was conducted in the orchards of Moghan Agro-Industrial Company, Moghan, Iran on hazelnut trees in a factorial form based on a randomized complete block design with three replications. The studied treatments included compost of cow manure (M), vermicompost of cow manure (Vm), vermicompost enriched with Fe and Zn (Vm+Fe+Zn), vermicompost enriched with iron filings (Vm+ID), soil application of zinc sulfate and iron sulfate (ZnSO4+FeSO4), spraying of Fe and Zn chelate (FCFe+Zn), spraying of iron sulfate and zinc sulfate (FMFe+Zn), soil application of Fe-EDDHA and Zn-EDDHA (EDDHAFe+Zn), sulfuric acid (H2SO4) and control. The results of leaf analysis showed Fe deficiency and Cu excess in the soil of the studied region. Enrichment of vermicompost with Fe and Zn decreased pH compared with compost and increased total and available concentration of Fe and Zn. The effect of mixing vermicompost with iron sulfate was better than mixing it with iron filings. The highest yield was obtained with Fe- and Zn-enriched vermicompost. Different treatments increased leaf Fe, Zn and chlorophyll concentration and yield compared with control, but enrichment with Fe and Zn was more effective than other treatments. The measurement of leaf chlorophyll is a simple, appropriate method for assessing the nutritional status of Fe and Zn of hazelnut trees because of the similar pattern of leaf chlorophyll content and their chlorophyll amount.

Given that drought is a natural disaster and poses a major threat to agriculture in most parts of the world, especially Iran, selecting drought resistant, high-yielding genotypes is necessary. Therefore, to evaluate the drought tolerance of durum wheat genotypes, an experiment was carried out on 35 indigenous landraces in Ardabil, Iran in 2009 under normal and drought-stressed conditions. The experimental design in each water treatment was a randomized complete block design with two replications. The results of analysis of variance showed that irrigated conditions significantly affected plant height, grain number per main spike, main spike weight, 1000-grain weight, yield and harvest index. The landraces of Boeuffi and Africanum had the highest grain yield under both optimum and stressed conditions. They also had optimum harvest index, 1000-grain weight, grain number per main spike and plant height. In addition to having high yield under optimum conditions, they exhibited acceptable tolerance to water stress, too. The stress tolerance index (STI) and mean productivity (MP) had the highest positive, significant correlation with each other and were found to be the most effective indices for selecting drought resistant cultivars.

To evaluate the effect of light and dark mulches on quantitative and qualitative traits of three tomato cultivars, a factorial experiment was conducted in Kahnooj, Iran, in 2010 based on a randomized complete block design with four replications. The factors included three cultivars (Falat, Chef and Kalji) and three mulch treatments (light, dark and no-mulch). The results showed that light mulch produced the highest early fruit yield (691.50 g.plant-1) and total yield (2010 g.plant-1), and control treatment (no-mulch) had the lowest early fruit yield (287.60 g.plant-1) and total yield (980.40 g.plant-1). The cultivars Chef and Kalji had the highest and lowest early fruit yields (811.2 and 163.5 g.plant-1), respectively. In addition, dark and light plastic mulches significantly impacted the control of broomrape disease. It is recommended to use light and dark mulches in order to increase early fruit yield and total yield of tomato and suppress broomrape.