نشریه اکوفیزیولوژی گیاهی
پیاپی 19 (زمستان 1393)

Water deficit is one of the main factors limiting production in arid and semiarid regions. This study was carried out to investigate the effect of the interaction of water deficit and N fertilizer rate on relative water content, proline content, leaf chlorophyll content, pollen number and pollen viability, photosynthesis rate and stomata conductance parameters in two hybrid sweet corn (968 and 926) in greenhouse condition. The experimental layout was split plot factorial design arranged in a randomized complete block design with three replications in 2010 in the Agriculture Crop Science, Putra University Malaysia (UPM). Treatments consisted of four levels of irrigation (including irrigating all the growing season (control), vegetative drought, reproductive drought and vegetative and reproductive drought), three levels of Nitrogen as urea (40, 120 and 200 kg ha-1) and two varieties of sweet corn varieties (including hybrids 968 and 926), respectively. Results showed that the interaction effects of water deficit and Nitrogen fertilizer were significant and reduced leaf chlorophyll content, photosynthetic rate and stomata conductivity under water and Nitrogen rate deficit. Also the results showed that water deficit at vegetative and productive growth stages reduced photosynthesis rate compared to normal irrigation by 54% and 84%, respectively. But Nitrogen treatments at 200 and 120 kg ha-1 did not show any significant decrease in stomata conductivity. Whereas. Proline content increased under water deficit. Pollen number reduced with water and nitrogen deficit. Pollen viability reduced only under water deficit by 39%.

In order to investigate the effects of zinc and nitrogen foliar application on yield and yield components of soybean, a field study was conducted in Roudsar, Guilan province, during growing season of 2012. The experiment was factorial in randomized complete block design with three replications. Treatments consisted of four levels of nitrogen fertilizer including: N1-control, N2- 30, N3-60 and N4- 90 kg/ha from urea source and zinc treatments in 4 levels including: Zn1- control, Zn2- 0.5, Zn3- 1 and Zn4- 1.5 lit/ha. Results showed that nitrogen levels had significant effects on the number of pod per plant, number of seed per pod, 100 seed weight, grain yield, biomass, height of plant and length of pod. In the experiment zinc treatments, had significant effects on the number of pod per plant, 100 seed weight, grain yield, biomass, harvest index, height of plant and length of pod. Also interaction of nitrogen and zinc treatments had significant effects on the number of pod per plant, number of seed per pod, 100 seed weight, grain yield and harvest index. The 90 kg/ha nitrogen treatment and 0.5 lit/ha zinc application resulted in the most yield (5902 kg/ha) that didnt show any significant difference compared with 60 kg/ha nitrogen and 0.5 L/ha zinc (5682 kg/ha). The application of 60 kg/ha nitrogen and 0.5 lit/ha zinc is recommended in soybean in north of Iran.

Increasing plant density with the purpose of yield increasing, sometimes increases lodging in wheat that decreases photosynthesis and yield. A field experiment in factorial based on complete randomized block design was conducted in Agricultural Research Station of Zargan (Fars, Iran) to evaluate the effects of plant density and chlormequat chloride (CCC) on wheat lodging. The first factor was four plant densities (200, 300, 400 and 500 plants/m2) and the second factor was three chlormequat chloride concentrations (0, 1000 and 3000g/ha). The results indicated that the effect of plant density was significant (p<0.05). Increasing plant density up to 500 increased lodging but the effect of different levels of CCC on lodging was not significant. However, the interaction of the two factors caused significant changes on lodging. The result also indicated that plant density had a significant effect on dry matter, photosynthesis (pre and post anthesis) and grain yield but no effect on other characteristics. CCC had significant effects on dry weight, photosynthesis (post anthesis) and the interaction effect of CCC and plant density (400 plant /m2) and 3000 g CCC had the highest grain yield and lowest lodging.

Yield loss in sugar beet due to weeds is higher than pests and diseases. To investigate the effect of duration of weed interference on quantitative and qualitative yield of sugar beet in different agriculture management systems, an experiment was conducted as split plot design based on randomized complete block design with three replications on Barakat farms Jovain Agricultural and Industrial Company (60 Km southeast of Sabzevar) in 2012-2013. The main factor was Nitrogen amount (100, 200 and 300 kg.ha-1 Low, medium and high, respectively). And weed interference duration (0, 30, 45 and 60 days after emergence include full-season interference of weeds) was as the subplot. Results showed increasing nitrogen, increased dry weight per unit area of weeds, but weed density was not affected by different amounts of nitrogen. The highest root yield sugar yield and percentage of net sugar were derived by application of 300 kg.ha-1 while molasses sugar, α-amino-N and Na+ observed at 300 kg.ha-1. Increasing duration of weed interference reduced root yield (57.2%), sugar yield (83.69%), net sugar (16.01%), Na+(34.54%) K+ (17.37%) and increased alkalinity (11%) compared with those of the control. The highest root yield and sugar yield was observed in the control treatment that hadnt significant difference with 30 days weed interference. Increasing duration of weed interference reduced weed density and increased weed dry weight. In low and high (100 and 300 Kg. ha-1) amounts of nitrogen, sugar beet was less competitive than weeds whereas medium level (200 Kg.ha-1 N) sugar beet was more competitive than weeds. Overall, weed control in 30 days after emergence and use of 200 Kg.ha-1 N was the best treatment.

Yield components and genetic contribution in final yield have important roles in crop plants breeding programs. For this purpose, 20 varieties of grapevines with Russia origin were evaluated in Urmia and Takestan research station (under full irrigation and drought stress). This research was performed in randomized complete block design with three replications and three plants in each plot in 2012. Number of cluster per plant, number of berry per cluster, berry weight and yield per plants were recorded. Compound and logarithmic analysis of variance, genotype and environmental interaction effects were estimated by multiplicative three environmental and genotypic elements. Results of path analysis indicated that the number of cluster per plant had the highest genetic contribution in final yield and the most sensitivity and variation in different environments. Direct effect of the number of cluster per plant in final yield (0.61) was higher than direct effect of the number of berry per cluster (0.48) and berry weight (0.30). Path coefficient of number of cluster per plant value was higher than path coefficient berry per cluster and berry weight.Therefore, the sequence of manifestation of yield components was number of cluster per plant, number of berry per cluster and berry weight, respectively. Environmental components of interaction effects indicated that absolute value of number of cluster per plant was higher than number of berry per cluster and berry weight. This indicated higher sensitivity of number of cluster per plant in different environments.

Investigating and identifying soil contaminants soil are essential. A wide range of techniques are available for the removal of metal ions from polluted environments. Each of them has advantages and disadvantages based on simplicity, flexibility, efficiency of processes, cost, technical and maintenance problems. Therefore, easy, effective, economical and environmentally friendly techniques for treatments are needed. Use of organic absorbents is one of the newest and most appropriate cost techniques. In this study, soil was treated with citrus peel as low cost organic immobilizers in order to investigate the time effect on decreasing mobility of Ni and Zn. The soil was artificially contaminated with Ni and Zn in separate containers. Both elements were incorporated at a dose of 600 mg l-1 and then citrus peel was added to soils at the rate of 5%. Sampling of treatments was in 1h, 1, 3, 7, 14, 21, 28 days of incubation. The experiment was done with 2 treatments including polluted soil samples with and without citrus peel as control in completely randomized design. Statistical analysis done using the SAS software (version 9.1) and Duncan test was performed at 5% level. Results indicated that at the first time of incubation, the pH of soils decreased due to the presence of citrus peel and increased the availability of metals. But the prolonged incubation time led to increasing metal adsorption onto organic adsorbent surfaces and decreasing the metal concentration in exchangeable fraction. Mean Zn concentrations in the control soil and soil treated with citrus peel, were 107.8 and 98.3 mg kg-1 and mean Ni concentrations were 144.5 and 134.4 mg kg,-1 respectively. Differences in control and the citrus peel treatment for both elements were significant.

In this study the biomass, proline content and enzyme activity of root and leaf ofZiziphus spina-christiseedlings under drought stress were studied in nursery conditions. For this purpose, the seedlings of Z. spina-christi were exposed to four levels of drought stress (25%, 50%, 75% and 100% field capacity) in nursery of Mehran city, Ilam with sub-tropical climate for 9 months. Finaly, survival, fresh and dry weight of root and shoot, proline content and activity of Catalase, Peroxidase and Superoxid-Dismutase enzymes of Z. spina-christiseedlings were measured. The results showed that drought stress decreased the survival, fresh and dry weight of shoot, root, root fresh weight and root volume. Also, drought stress increased Peroxidase and Superoxide-dismutase enzyme activities of seedling shoots. The free proline content of shoot in seedlings subjected to drought stress was higher than other treatments, but it affected proline content of roots. This study revealed that despite the drought resistance of Z. spina-christiseedlings, the biomass decreased and activity of peroxidase, superoxide-dismutase enzymes and proline content increased under drought stress condition.

In order to investigation of allelopathic activity of aqueous extract and different plant tissues residues of Amaranthus retroflexus, Portulaca oleracea, Chenopodiunm album, Dactyloctenium aegyptyum and Malva neglecta on seed germination and seedling growth of onion, laboratory and pot experiments were performed as a factorial experiment basis of a completely randomized design with three replications in Horticultural science Department of Hormozgan University. In laboratory experiment, studied factors were included five weeds species, six concentrations (0, 1, 2, 4, 8 and 10 ml) of aqueous extract of different tissues (leaf, stem and root) of tested weeds and in pot study, experimental factors included five weeds species, six amounts (0, 1, 2, 4, 8 and 16 gram per pot) of ground residues of different tissues (leaf, stem and root) of studied weeds. Results of this study indicated that in laboratory experiment, A. retroflexus and D. aegyptyum had the most allelopathic effects on onion. Although in most of the studied traits no significant differences were observed between these two weeds, but inhibition effects of A. retroflexus was higher for germination rate, radicel length and dry weight and seedling dry weight. With increase in extract concentrations, almost of onion seedling growth characteristics decreased significantly. Results of pot experiment showed that the weed residues incorporated in soil inhibited the growth and leaf chlorophyll a content of onion. Both A. retroflexus and D. aegyptyum had the maximum inhibition effects on all of onion vegetative growth trails. But A. retroflexus allelopathic effects on seedling emergence percentage and chlorophyll a content were more obvious. Results of this study indicated that since between studied weed species, A. retroflexus and D. aegyptyum had the most allelopathic effects on onion seed germination and vegetative growth characteristics, therefore these two weeds must be controlled completely before onion cultivation.