JWSS - Journal of Water and Soil Science

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Nitrogen fertilizer application for corn (Zea mays L.) based on available N of soil can decrease the need to N fertilizer and, consequently, reduce the risk of environmental pollution, especially that of groundwater and drinking water. The objectives of this study were i) determining soil N0₃-N critical level at 4 to 6 leaf stage, ii) to study soil nitrate distribution, iii) determining N rate required for maximum corn grain yield, iv) measuring soil residual nitrate nitrogen after harvesting, and v) using hand chlorophyll meter to evaluate N status of corn. The experiment was conducted under field conditions in Bajgah and Kooshkak research stations (Fars Province) in 1996 using a split plot randomized complete block design with four replications. Main plots were control, 60, 120, and 180 kg N ha^-1 as urea. At 4 to 6 leaf stage each main plot was divided into two sub-plots and N was applied at 60 kg N ha^-1 rate to one sub-plot and the other sub-plot was left as control.

 Results showed that critical soil N0₃-N level at 4 to 6 leaf stage in 0-30 cm depth for 90 percent relative yield in Bajgah was 12-14 and for Kooshkak was 8-10 mg kg^-1 soil. The highest coefficient of determination between corn grain yield and soil N0₃-N in 0-30 cm depth for Bajgah was in furrow sample and for Kooshkak was in furrow and shoulder composite sample. In both sites, maximum corn grain yield, with 15.5% moisture content, was about 14 mg ha^-1 that was obtained through the application of 120 kg N ha^-1 as preplant plus 60 kg N ha^-1 as sidedress which is about 1/2 of the application rate used by local farmers. The highest residual soil N0₃-N after harvesting was 24 and 18 and the lowest was 2.6 and 3 mg kg^-1 soil for Bajgah and Kooshkak soils, respectively. When maximum corn grain yield was obtained, chlorophyll meter reading at the middle of leaf blade at dough stage, was 49 for both sites. It seems that N fertilizer application rate by local farmers is excessive.

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Nitrogen is usually the most limiting nutrient for crop production. Manganese deficiency in some calcareous soils of Iran has been reported. The objective of this study was to evaluate the effect of N and Mn on the growth and chemical composition of spinach (Spinacia oleracea L.) under greenhouse conditions. The experiment was conducted in a soil from Chitgar series (Fine-loamy, carbonatic, thermic, Calcixerollic Xerochrepts). Treatments consisted of factorial arrangement of five N rates (0, 50, 100, 200 and 400 mg kg^-1 as NH₄NO₃) and three Mn rates (0, 15 and 30 mg kg^-1 as MnSO₄) in a completely randomized design with four replications. Plants were allowed to grow for 60 days and a hand-held SPAD-502 chlorophyll meter was used to evaluate leaf chlorophyll status at harvest.

 Results showed that N and Mn application increased shoot dry weight, N and Mn concentrations and total uptake, Mn:Fe ratios and chlorophyll readings, significantly. Nitrogen increased concentrations and total uptake of Zn, Cu and total uptake of Fe in plants, but decreased Fe concentration. Addition of Mn decreased Fe and Zn concentrations in spinach but increased total uptake of Fe and Cu. When maximum dry matter was obtained, the chlorophyll meter reading was about 40. A similar study should be carried out under field conditions before the N and Mn fertilizer recommendations for spinach can be made.

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In a pot experiment, the growth (Dry matter) responses of 18 rapeseed varieties to three levels of NaCl salinity induced by 1.2, 6, and 12 dS.m^-1 were investigated using a factorial experiment with a randomized complete block design in 3 replications. The results indicated that salinity reduced total dry matter, Na concentration, K/Na ratio, ion selectivity of K versus Na, and leaf water potential while it increased K concentration. However, the leaf water potential of the plants had the highest and a significantly negative correlation with total dry matter accumulation. Therefore, it seemed that leaf water content of the plants could explain the tolerance or sensitivity responses to salinity. The rapeseed varieties were accordingly ranked into different groups. The varieties viz, Alice, Fonax, DP.94.8 and Licord were classified as saline tolerant group, and varieties such as Okapi, Akamar and Eurol as saline sensitive group. The remaining eight rapeseed varieties were moderately tolerant. Moreover, the response of rapeseed varieties viz. Consul, VDH8003-98 and Orient were different such that the above explanation could not be applied to them. Therefore, halophytic strategies for these three varieties might be worth further investigation.

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Turfgrasses are the most important cover plants in the world. Quality evaluation of the turfgrasses is usually done by experienced evaluators using color texture, density and uniformity. The results obtained by different evaluators may be different, leading to researcher’s concern. Therefore, some quantitative methods have been used for increasing the aquracy and stability in results. In this study, three color evaluating methods including, spectrophotometery (chlorophyll content), chlorophyllmeter SPAD-502, and evaluator person, as well as leaf texture by evaluator person compared with leaf width were used for 75 populations of Cynodon dactylon L. and Tifdwarf cultivar. The results showed that there were significant differences between populations for the color and leaf texture. There were no significant corelations between measuring color by using specterophotometery, chlorophyllmeter-502, and evaluator. Use of SPAD-502 instrument for measuring leaf color of bermudagrass is not recommended due to small leaf width of this species. However, there was significant corelation between visual evaluation and leaf width in measuring leaf texture. Therefore, when no experienced evaluator is present, leaf width maybe used for measuring leaf texture.

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In order to study the effects of salinity on germination, vegetative growth and some physiological characteristics of canola cultivars, two experiments were conducted at Research Station of Agricultural College of University of Kerman in 2004. The experimental design was a Completely Randomized Block with four replications. Treatments comprised all combinations of different levels of three factors including variety (Kobra × Regent, Ceres and Okapi), salt type (NaCl, CaCl₂) and electrical conductivity of saline solution (0, 4, 8, 12 dS/m). Results of variance analysis showed that salinity has a very significant effect on germination percentage, germination homogeneity, germination rate, rootlet and polomul length at the end of the germination stage. Shoot length, dry weight, diameter and number of nodes per shoot were significantly affected also by salinity at vegetative growth. Regarding the two types of salt, none of the measured traits were significantly different. All the mentioned traits decreased with increasing salinity the highest and the lowest values were recorded at control and at 12 dS/m salinity levels. Membrane ion leakage was the only trait which increased significantly. Comparison of means showed germination percentage and germination homogeneity at germination stage and the number of nodes at vegetative growth stage were affected less than other traits by salinity, and they only decreased significantly with increasing salinity to 12dS/m. The effect of cultivar on these traits was also significant (P<0.001). In both growth stages, cultivars response to salinity was different. At germination stage, Ceres and Kobra * Regent cultivars were the most sensitive and tolerant ones in terms of all traits and there was no significant difference between Okapi and Kobra *Regent. At vegetative growth stage, however, Okapi showed less growth than Kobra * Regent and their difference was significant. It seems that evaluation of traits response at germination stage can not be effective to determine salt tolerance of canola cultivars.

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A pot experiment was designed to investigate the effects of full, above and below ground interactions of wheat with wild oat on leaf characteristics and root to shoot ratio. This experiment was conducted as a factorial based on randomized complete design with four replications. The treatments included four interference levels (above ground, below ground, above and below ground and check wheat and wild oat) and four wild oat densities (2, 4, 6 and 8 plants/pot).The effects of full and root interference on wheat and wild oat traits was greater than shoot interference. For both species, full and below ground interaction significantly decreased the number of leaves, flag leaf area and chlorophyll content of flag leaf compared to above ground interaction and control. All traits of wild oat were reduced by above ground interaction compared to control. Number of leaves of wheat and wild oat showed greatest susceptibility to interaction treatments. There was no significant different between full and root interference. When wild oat density increased, the number of leaves, flag leaf area and chlorophyll content of flag leaf of wheat decreased. With strongest competition followed by enhanced wild oat density, root to shoot ratio in wheat and wild oat increased, which indicates more susceptibility of shoot than root to interference mean competition. This ratio for wild oat was more than wheat, thus, it is concluded that wild oat has higher rooting ability compared to wheat.

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This study was conducted in Research Farm of Isfahan University of Technology to evaluate some of the agronomic and physiological traits and grain yield potentials of ten bread wheat cultivars using a split plot design with three replications. Main and sub plot consisted of optimum and stress moisture treatments (irrigation after 70±3 and 130±3 mm evaporation from class A pan) and wheat cultivars, respectively. The results of analysis of variance revealed significant effect of moisture treatments on all traits except 1000-grain weight, harvest index, specific leaf weight, assimilate redistribution and difference of peduncle weights at heading. Significant differences were found among genotypes in the stress condition except for chlorophyll b and chlorophyll a to b ratio. Significant differences were detected among genotypes in optimum moisture condition for all characters, except for chlorophyll b, chlorophyll a to b ratio, harvest index and assimilate redistribution. Grain yields in two moisture conditions had significant positive phenotypic and genetic correlations with harvest index, number of grain/spike, RWC, chlorophyll a and sum of chlorophylls a and b and had significant negative correlation with RWL. Significant positive correlation was observed between peduncle weight at heading stage and difference of peduncle weights at stages heading and maturity with grain yield and RWC in moisture stress condition. The results of path analysis for phenotypic correlation coefficients between grain yield and their corresponding traits in the regression model showed that in stress condition harvest index had the highest direct and positive effect on grain yield and in non stress condition chlorophyll a had the highest direct and positive effect on grain yield. Results of stepwise regression analysis in non stress condition revealed that chlorophyll a, plant height and harvest index explained more than 90% of grain yield variability. Based on stepwise regression analysis in non stress condition, RWL, harvest index and RWC explained 95% of grain yield variability.

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Many experiments have been carried out to decrease the negative effect of drought stress and obtain suitable growth under water deficit conditions. Application of plant growth regulators (especially growth retardants) is one of the proposed methods. This study was conducted to investigate the effect of Cycocel application on growth of two olive cultivars (Shengeh and Roghani) under water stress condition. The design of experiment was completely randomized with six replications (Factorial arrangement). Treatments included irrigation intervals (2, 4, 6, 8 weeks) and Cycocel concentrations (0, 500,1000,2000,4000 mg per litter). Some indices such as height, chlorophyll, leaf area, root, and shoot weight (fresh and dry) were measured. Results indicated that interaction of C.C.C treatment and irrigation intervals on height of olive cultivars was not significant, probably due to the response of these cultivars to concentrations of C.C.C. Although drought stress decreased the number of leaves in both cultivars, the application of CCC (500 mg per litter) thwarted the adverse effects of drought stress. Cycocel increased chlorophyll content significantly (500 mg per litter in Roghani and Shengeh and 6 weeks irrigation interval). Cycocel application decreased leaf area, but in Shengeh cultivar increased leaf area in 6 week irrigation interval. Overall, the results indicated that the application of Cycocel with concentration of 500 mg per litter in 6 week irrigation intervals in both cultivars (Roghani and Shengeh) was the best treatment for controlling the adverse effects of drought. Also, results indicated that such changes were dependent on Cycocel concentration and drought level.

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The growth and fluorescence parameters of chlorophyll in four corn hybrids including two sweet (K.S.C. 403 and K.S.C. 404) and two grain hybrids (S.C. 500 and S.C. 700) were evaluated in response to Fe and Zn nutrition in a nutrient solution culture. This study was conducted in a randomized complete block design with a factorial arrangement with three replications at the Soilless Culture Research Center (SCRC). Corn hybrids were exposed to two Fe levels (5 and 50 µM Fe in the form of FeEDTA) and two Zn levels (0 and 2 µM Zn in the form of ZnSO4). Increasing Fe concentration in the nutrient solution increased F0, Fm, and Fv/Fm values by 48, 96, and 123%, respectively. The fluorescence parameters of chlorophyll were affected by corn hybrid and there were significant differences in F0 and Fv/Fm at 1% level and Fm at 5% probability level among the studied hybrids. Iron deficiency significantly (P<0.05) reduced the root dry weight of all the studied hybrids. Zinc deficiency resulted in a significant decrease in the root dry weight of H403 and H500 hybrids while no significant decrease was found in the root dry weight of the H404 and H700 hybrids under Zn condition. The results showed that corn hybrids varied significantly in their tolerance to Fe and Zn deficiency. Based on the results of plant growth and fluorescence parameters of chlorophyll, the studied grain corn hybrids were more tolerant to Fe and Zn deficiency conditions in comparison with sweet corn hybrids. It seems fluorescence parameters of chlorophyll might be suitable parameters to screen corn hybrids in their tolerance to Zn and particularly Fe deficiency condition.

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Iron chlorosis is an important disorder of plane trees (Plantanus orintalis L.) in green space of Isfahan city. Before using reclamation methods for correcting Fe chlorosis, it is necessary to find a suitable index for evaluating plant Fe status. Therefore, activity of glutathione peroxidase (GP) enzyme and concentration of carotenoids and chlorophyll a and b pigments, as physiological indices of active Fe, were compared to total Fe concentration in leaves to evaluate Fe status in plane trees. For this purpose, severity of chlorosis of plane trees at different regions of Isfahan city was recorded. Then, 73 trees with different severity of chlorosis symptoms were selected and their leaves were sampled on July 2009 and 2010. Concentration of Fe, chlorophyll a and b and carotenoids in leaves as well as activity of GP enzyme were measured. Results showed large variation in leaf Fe concentration between young and old leaves and also between leaves with different chlorosis severity symptoms. No correlation was found between leaf Fe chlorophyll concentration and severity of chlorosis symptoms. Also, concentrations of chlorophyll a in young and old leaves with very severe chlorosis symptoms were 44 and 37% smaller than that in young and old leaves with slight chlorosis symptoms, respectively. Concentration of chlorophyll b in young and old leaves with very severe chlorosis symptoms were 40 and 37% smaller than that in young and old leaves with slight chlorosis symptoms, respectively. Concentration of carotenoids varied among young and old leaves with different severity of chlorosis symptoms. Activity of GP in young leaves was also reduced by intensifying severity of chlorosis symptoms. According to the result of the present study, activity of GP enzyme and leaf concentration of carotenoids and chlorophyll a, as suitable physiological indices of active Fe, had close correlation with severity of Fe chlorosis in plane trees. Also, deficiency of active Fe in leaves is a probable reason of chlorosis symptoms in plane trees.

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Zinc deficiency is the most widespread micronutrient disorder in the production of wheat (Triticum aestivum L.) and other cereal crops. An experiment was conducted in greenhouse, in 2013, using the sterile sand-perlite (2:1 v/v), to study the effects of two beneficial microorganisms on growth and nutritional status of wheat (Nicknejad cultivar). The study was arranged as factorial in a completely randomized design with three replications. The experimental factors consisted of Piriformospora indica (E0: Uninoculated E1: Inoculated), Pseudomonas putida (E0: Uninoculated E1: Inoculated) and Zinc (Zn0: 0 Zn1: 2µM ZnSO4 ). The results showed that inoculation by P. putida increased shoot dry weight at both levels of zinc, but this increase was observed for root dry weight only without zinc application. The iron concentration of shoot was decreased as a result of inoculation by P. putida at both levels of zinc. However, P. indica inoculation increased iron concentration in zinc application, but had no significant effect without zinc application. At both levels of zinc, the highest P, Zn, chlorophyll a and b concentrations were achieved by inoculation with P. indica. Inoculation by P. putida reduced P concentration at both levels of zinc but it reduced Zn, chlorophyll a and b concentrations only with zinc application. The results of this research showed that despite negative effect of P. putida on nutrient uptake, inoculation by P. putida and/or P. indica plays an important role in the promotion of wheat growth in zinc deficiency conditions.

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