نشریه فیزیولوژی گیاهان زراعی
پیاپی 21 (بهار 1393)

In order to investigate the effect of nitrogen fertilizer rates on morphological characteristics, yield and grain yield components of corn hybrids in environmental conditions of Andimeshk, this research was conducted as split plot with randomized complete blocks design with three replications in 2011-12 cropping year. Four amounts of nitrogen fertilizer (without fertilizer, 90, 180 and 260 kilogram of net nitrogen in hectare) from the source urea fertilizer (46 percent nitrogen) in main plots and four corn hybrids (Single Cross 704, DKC6589, Mobin and Single Cross640) were placed in sub plots. Results of experiment showed that the effect of nitrogen on features plant height, stem diameter and leaf length was significant in one percent probability level, while the traits of ear height and the number of leaves above the ear were not affected by this treatment. Hybrid DKC6589 as regards to all of the studied morphological traits compared to other hybrids had superiority. Increasing the rate of nitrogen increased the average of corn hybrids grain yield, but difference of this trait was not significant in fertilizer application treatments. The highest grain yield was obtained in hybrid DKC6589 and 180 kilo gram in hectare nitrogen. Increasing nitrogen up 260 kilogram in hectare significantly increased the grain yield of Single Cross 640, but in other hybrids, increasing nitrogen more than 180 kilogram in hectare, decreased the grain yield slightly. DKC6589 hybrid had more grain yield compared to other hybrids due to favorable morphological features, the number of grain per row and higher 100-grain weight. Further research is recommended to investigate the potential of hybrid DKC6589 production in Khuzestan province.

Growth response and yield of barley in response to cycocel among different cultivares is different, considerably. For this purpose, growth changes during the season and yield of five cultivares of barley as affected by cycocel application was conducted in a field research in College of Agriculture of Shiraz University in two cropping years 2010-2011 and 2011-12. In this research the effect of cycocel with three concentrations zero (water as control), 2 and 4 gram per liter on growth and yield of five barley cultivars Viktoria, Reyhan, Jonoub, Gorgan and Valfajr was investigated. The results showed that cycocel foliar application at the begining of growing season decreased the stem height in all cultivars of barley, however, this reduction of height was compensated in the end of growing season so that there was no significant difference between the ultimate height of the folior application treated plants with control plants.This height reduction at tillering time led to more survival of tillers and enhancement of fertile tillers and consequently resulted in increasing grain yield. The highest grain yield was obtained in Reyhan cultivar with cycocel folior application with concentration 4 gram in square meter (734/47). Cycocel had positive effect on increasing leaf area index during the season from 150 days after sowing onwards. Dry weight of plant in folior application treated plants had the higher increasing during growing season, in this regard the positive effect of concentration 4 was more than 2 gram per liter. Overall, the results indicated that Reyhane and Gorgan cultivars had the highest and lowest response to cycocel application. Thus, Reyhan cultivar is recommendable in such conditions.

In Khouzestan, reduce temperature in January and Februaryis a dominant climate phenomenon that causes damage to the plant and thus the yield. In this research the effect of cold tension in tillering stage on yield, yield components and some phonological and physiological traits was investigated in a factorial experiment under controlled greenhouse conditions with five wheat genotypes (cultivars Chamran, Virinak, Star, Karkheh and line M-83-17) and at four ambient temperatures (no cold, , 0, -3 C°) in a completely randomized design with three replications. The results showed there was a significant difference among genotypes in terms of cold tolerance and the genotypes difference and the effect of cold and their interactions on yield and yield components and some physiological traits was significant. At no tension conditions and 0 C° temperature the highest grain yield was belonged to line M-83-17 at rates 0.8 and 0.3 gram in main stem, respectively and Star cultivar at and -3 C° temperatures with 0.4 and 0.45 gram in main stem, respectively. The lowest fluorescence reduction was observed at least, at Chamran cultivar at 0 C° tension and the lowest fluorescence increase, maximum in Chamran cultivar at -3 C° tension. The maximum photochemical photosystem II efficiency was observed in Star cultivar. According to SSI and STI indices, Star and Chamran cultivars had more sustainability yield in cold tensions. The changes of investigated traits in the studied genotypes shows different reaction of genotypes which itself is due to genetic diversity of these genotypes.

This experiment was conducted in order to investigate the effect of post anthesis drought tension on agronomical traits, biochemical characteristics and some physiological characteristics. The experiment was carried out in pot culture experiment as factorial experiment based on complete randomized blocks design in three replications in Campus of Agriculture and Natural Resources of Razi University, Kermanshah in 2011-12 cropping year. In this experiment, drought tension was considered at generative growth stage (from the anthesis stage until end of soil moisture growth stage, around 30 percent of field moisture) and different wheat genotypes consisted of Pishtaz, DN-11, Sivand and Marvdasht were investigated as the second factor. The results showed that drought tension after anthesis decreased grain yield by decreasing of 1000- grain weight. Under drought tension after anthesis, Marvdast and DN-11 genotypes had the lowest grain yield. The occurrence of drought tension significantly decreased soluble protein content. The activity of superoxide dismutase enzyme increased after anthesis in drought tension conditions. Catalase and peroxidase activity in the sensitive genotypes (Marvdast and DN-11) was less than the tolerant genotypes (Pishtaz and Sivand). It can be concluded that activating the enzymes defense system of catalase, peroxidase and superoxide dismutase antioxidants in wheat genotypes has had a major role in increasing tolerance to drought tension.

This research was conducted in order to study the effect of using plant residues and zinc sulfate on the absorbability of zinc in soil and its concentration in the grain wheat as well as the effect on the concentration of phytic acid, phytic acid molar ratio and grain protein. The experiment was conducted in the form of a statistical randomized complete blocks design with eight treatments (control, zinc sulfate, alfalfa plant residues, beans and wheat and alfalfa plant residues, beans and wheat plus zinc sulfate) in three replications in a farm in Isfahan province, Dehaghan city. Due to the amount of organic matter and zinc in the soil, zinc sulfate by 60 kilogram per hectare and plant residues by 10 tons per hectare was added to the considered treatments. After that, the amount of 250 kilogram per hectare of common grain wheat of region (Sepahan cultivar) was planted. The obtained results showed that the application of zinc sulfate in the soil on the yield grain and zinc concentration of grin was significant. In treatment that plant residues with zinc sulfate was added in the soil, there was a significant increase in the measured properties compared to the control and plant residues application and zinc sulfate treatments. Among the plant residues of wheat, beans and alfalfa, alfalfa residues led to more increase in zinc concentration and grain protein and more decrease phytic acid and phytic acid to zinc molar ratio in grain. It can be concluded that the application of zinc with plant residues can cause more increasing in zinc concentration and grain qualitative parameters.

As regards to the high volume of imports of vegetable oil in the country and limited water resources, recognition factors affecting on crops production in low water conditions is very important. In order to investigate the effect of chitosan foliar application in deficit irrigation conditions on quantitative and qualitative characteristics of sunflower Alster cultivar, this experiment as split plots on the basis of randomized complete blocks design with three replications was conducted at the research field of Zabol Agriculture college in 2011-12 cropping year. The factors of experiment included drought tension in three levels watering based on 25 percent of available moisture (sever tension), 50 percent of available moisture (mild tension) and 75 percent of available moisture (control) as the main factor and chitosan foliar application at three levels: zero (control), two gram in liter and five gram in liter as sub factor. In this experiment drought tension caused reduction in plant height, one-thousand grain weight, biological yield, grain yield, harvest index, chlorophyll a, chlorophyll b, total chlorophyll, head diameter, but no significant effect was observed on harvest index and oil percentage. Also, foliar application of chitosan leaded to increasing plant height, one-thousand grain weight, biological yield, grain yield, head diameter and total chlorophyll.

In order to investigate the effect of nitrogen application on improving the yield, grain yield components and changing grain compositions of safflower Goldasht cultivar, this experiment as a randomized complete blocks design was conducted with four replications in research station of College of Agriculture of Mohaghegh Ardabili University in Ardabil province in 2011 cropping year. Treatments of experiment consisted of five levels of nitrogen fertilizer (urea source 46 percent) 0, 50, 100, 150 and 200 kilogram nitrogen in hectare. Results showed that use of different levels of nitrogen fertilizer had a significant effect on measured traits. Consumption of 200 kilogram in hectare nitrogen increased chlorophyll rates (26 percent), potassium (47 percent) and calcium (27 percent) and decreased sodium (39 percent) in plant. Maximum number of head per plant and grain in head obtained from the consumption of 200 kilogram nitrogen in hectare, while the highest 100-grain weight was obtained with consumption 150 kilogram nitrogen in hectare. The lowest and highest grain yield (1729.5 and 3087.9 kilogram in hectare) was observed in lack of consuming fertilizer and application of 200 kilogeram nitrogen in hectare, respectively. Between fertilizer levels of 50, 100 and 150 kilogram nitrogen in hectare, there was no significant difference in oil content, but consumption of 200 kilogram nitrogen in hectare allocated the highest reduction of the oil (25.7 percent). Despite the negative impact of nitrogen consumption on grain oil percent, oil yield increased with increasing fertilizer consumption and its highest amount (794.04 kilogram in hectare) was obtained from using 150 kilogram nitrogen. The grain protein content was increased from 19.40 percent at the control treatment to 25.10 percent in the highest level of fertilizer and also caused increasing in the amount of grains nitrogen. As regards to this point that in the most measured traits there was no significant difference between the rates of 150 and 200 kilogram nitrogen, for this reason in order to reduce economic and environmental costs using 150 kilogram in hectare nitrogen can be recommended.

In order to investigate the effect of different nitrogen amounts on grain yield and nitrogen use efficiency in Durum wheat genotypes, this experiment was conducted as split plots in randomized complete blocks design with four replications in 2012-2013 cropping year. Nitrogen as main factor was including: 45, 90 and 134 kilogram net nitrogen in hectare and sub factor three wheat cultivars consisted of Yavarus, Showa and the S78. The results showed that the effect of nitrogen treatments on yield of wheat cultivars was significant. The highest biological yield (1376 gram in m-2), grain yield (494.6 gram in m-2), grain number per spike (32.58) and one thousand-grain weight (39.86 gram) was obtained in treatment application of 135 kilogram net nitrogen in hectare. Line S78 had the highest grain yield (488.1 gram in m-2), biological yield (1389 gram in m-2) and grain number per spike (32.64). In contrast the lowest grain yield (394.4 gram in m-2) belonged to Yavarus cultivar. In addition, the highest nitrogen use efficiency was obtained in the minimum amount of fertilizer used and S78 line. Generally, treatment of using 135 kilogram net nitrogen in hectare in S78 line produced the highest grain yield.