CROP PHYSIOLOGY
Year:2013 | Volume:5 | Issue:17|Papers Count:10

In the region with drought stress, an efficient root system plays as major role in the success of production. In order to investigate the effect of foliar application of methanol on root characteristics of chickpea (Karaj variety) under drought stress conditions, a factorial experiment was conducted based on completely randomized design with three replications in September 2011 at the Reasearch Center of Plant Sciences of Ferdowsi University of Mashhad. Foliar application factor of methanol including 5 levels, 0 (control), 20, 25, 30 and 35 volumetric percentage which added to every levels of Glisin 2 gr/lit at three times during growth season of chickpea and with 10 days intervals. Spraying seedling was continued until running the solution drops on the leaves. The drought factor including drought stress (25 percent of field capacity) and without drought stress (100 percent of field capacity) was implemented. Results showed significant s difference between different levels of methanol regarding to root dry weight, tap root length and area, total roots length, ratio of root to leaf area and ratio of root area to leaf area (p<=0.05). Foliar application with %25 voluminal level, increased root dry weight rate, total roots length and roots area significantly in comparison with other treatments. Interaction between stress and methanol had significant effect on total roots length rate and the ratio of rot to shoot (p<=0.05). Totally, foliar application 25 and 30 percent voluminal of methanol can be recommended for increasing yield in chickpea.

In order to investigate the effect of Arbuscular-Mycorrhizal fungi on growth in Berseem clover (Trifolium alexandrum L.) plant under different levels of sewage sludge, a greenhouse experiment was conducted in a randomized complete block design with twelve treatments and three replications. The treatments of the experiment were a combination of three Mycorrhizal fungi status (Mi=Glomus intraradices, Mm=Glomus mosseae and M0=non-inoculation) and four sewage sludge levels (S0=0, S1=25, S2=50 and S3=100 ton per ha). The results showed that adding sewage sludge significantly increased dry weight growth parameters of clover, root dry weight, root length and weight of nodes in clover plant, but the percentage of roots colonization was significantly reduced. Root inoculation of clover plant with two species of Arbuscular-Mycorrhizal Fungi had positive and significant effect on most growth parameters of clover in comparison to non-inoculation.

Wheat is an important food and strategic product that is considered equal to oil or even better than it. In this research, yield components of selected promising lines of wheat in comparison with two control varieties in two continuous cropping years, were carried out in Isfahan. The studied yield components including days to spike appearance, days to physiological maturity, plant height, spike size, grain yield and 1000-grain weight. The results on comparison of the wheat promising lines and the control varieties of Bahar and Pishtaze indicated that the tentative lines in regards to the total studied factors in the first and second year of the experiment and also compound analysis of two years including days to spike appearance, days to physiological maturity, plant height, spike height, 1000-grain weight and grain yield to each other and in comparison with different control varieties and with significant effect in %1 probability level, is distinguishable. Also, the chart of cluster analysis results in wheat promising lines and the varieties and in addition correlation coefficients of yield component of wheat selected promising lines were with a very highly significant effect in promising lines and the varieties that is in agreement with the studied Duncan groups and comparison of mean.

This experiment was carried out in cropping years 2010-2011 in Agricultural Research Center of Dezful as split plot in a randomized complete block design with three replications. Treatments consisted of three cultivars of mung bean seeds (Parto, Indian lot and promising line of mung VC61) in subplots And three irrigation levels (no stress, mild stress and severe stress with 120, 180 and 240 mm from evaporation pan, respectively) were in the main plots. In this investigation, physiological traits including chlorophyll content, stomatal conductance, biological yield and leaf area index were measured. Drought stress had a significant effect in one percent level on chlorophyll content and stomatal conductance, decreasing in chlorophyll content and stomatal conductance in leaves was observed. Also, there was significant difference in cultivars and stomatal conductance was the highest in VC61 cultivar. VC61 cultivar with the 71.71 had the highest SPAD value and the amount of chlorophyll a+b VC61 cultivar, Indian and Parto cultivar was 1.364, 1.148 and 1.213, respectively. Drought stress had a significant effect on biological yield and the leaf area index at 5% level. Such as this traits decrease with severity of drought stress.

In order to investigate germination parameters, two separated experiments were done as a factorial form with completely randomized design including heat experiment (factors were planting date and cultivars) and drought experiment (factors were levels of stress and cultivars) with three replications. Germination parameters experiments maternity seeds including germination percentage, seedling, plumule rootlet length, seedling, plumule and rootlet dry matter weight, alometric index and seed vigor. Results showed that drought and heat stress has reduced seed weight at %5 probability level and has led to produce wrinkled and low weight seeds. Average germination percentage due to drought and heat stress were reduced 23% and 48%, respectively. Length and dry matter seedling which is a scale of mother seed vigor significantly reduced by drought and heat stress effect. Seedling length of the seeds which were obtained of planting date November11 compared to planting date Januray10 was reduced from 14.2 to 5.9 centimeter that equaled 59%. Drought stress reduced maternity seeds vigor form 14.1 to 9.01 that equaled 36% and heat stress reduced maternity seeds vigor form 13.45 to2.75 that equaled 80% and it showed that seed vigor decreased more due to by heat stress. Heat and drought stress because of reducing maternity matter storage in seed by lowering seed weight led to reduced plumule and rootlet growth, and finally quality of produced seeds. Hence, with management these two stress we can improve the quality and production of rapeseed and yield.

In order to investigate the effect of seed aging and plant density on yield and yield components of wheat (CV. Chamran), an experiment was conducted in 2010-2011 cropping year in Agricultural Research Center of Safi-Abad (Dezful).The experiment was factorial with randomized complete block design with three replications. The treatments consisting of seed aging in five levels (control, 48, 72, 96 and 110 hr) and plant density (300, 350, 400 and 450 plant m2).The results showed that seed aging decreased field indices as grain number per spike, spike density, harvest index, biological and grain yield. The mean comparison of aging simple effect showed that the highest (4179 kg ha-1) and the lowest (3166 kg ha-1) grain yield belonged to control treatment and treatment with 110 hr seed aging, respectively. The effect of plant density on the traits such as spike density, 1000-grain weight, biological yield and harvest index was significant, too. In addition, the correlation between grain yield and biological yield, harvest index, spike density and 1000-grain weight was positive. In this study, observed that temperature and seed aging duration are the most important factors that influence the occurrence and progression of seed aging. Hence, the development of seed aging with increasing temperature and its implementation duration is predictable.

In order to investigate the effects of seed density on grain filling process of barley genotypes, a factorial experiment was conducted in a randomized complete block design by using three genotypes of barley (Ezeh, Dopar Mahali and wi2291) and five seed densities (100, 200, 300, 400 and 500 grain m2) during cropping year 2006–2007 in agricultural research station of KhorrmAbad. To estimate grain growth factors, after pollination during eight samples taken at intervals of five days, the dry weight of one grain was measured. The results showed that the spike weight with number of spike m-2 (r=-0.82**) and filling rate with duration of grain filling (r=-0.78**) had a highly significant and negative correlation. The correlation between grain filling rate and grain yield was negative and highly significant (r=-0.44**) and non-significant correlation between the duration of grain filling and grain yield. Grain yield with biological yield, harvest index, hectoliter weight and spike number m2 had significant and positive correlation and significant and negative correlation with grain filling rate. Changes trend of single grain dry weight of the three genotypes of barley showed the highest dry weight of one grain was related to density 100 grain m2 and the minimum weight of the single grain of the mentioned genotype was related to density 400 grain m2. Seed genotypes filling rate between 1.213 to 1.333 mg per day and the different seed densities between 1.321 to 1.161 mg per day and for interaction between genotype and density between 1.070 to 1.620 mg per day ranged. Genotypes grain filling period between 33.72 to 38.72 days and for different seed densities between 32.70 to 39.94 days and for the interaction between genotype and density between 29.20 to 45.38 days ranged. It seems that in areas with climates with the final drought season stress, using varieties with higher grain filling rate are preferred.

Remobilization and retransfer of the stored Carbon from vegetative tissues to the grain in monocarpic plants requires the initiation of whole plant senescence by an unknown mechanism. This study examined the relationship between the senescence induced by water stress and C remobilization during grain filling. Two wheat cultivars, Marvdasht and Zagros (sensitive and tolerant to terminal season drought, respectively) grown at a day: night temperature of 15: 22oC from anthesis were compared as well watered treatments control (Field Capacity) and water deficit treatments 50% FC imposed either from anthesis to 14 days later (WS1) or from 14 days after anthesis to physiological maturity (WS2). The experiment was conducted into the plastic flowerpots in a greenhouse and a factorial RCBD with three replications. Results showed that water stress treatment, both at WS1 and WS2, facilitated the reduction in concentration of total soluble sugars in the internodes and promoted the remobilization of pre-stored C from two internodes to grains. WS2 treatment resulted in more deleterious effect on grain yield than WS1 treatment in both cultivars and led to a smaller kernels and lesser aerial biomass at maturity time. The results of this research showed that the senescence and the stored compounds remobilization promoted by moisture stress during grain filling are coupled processes in wheat, the amounts of soluble sugars in the stem is more important than sugar remobilization efficiency. Varietal differences in the extent of such studied traits existed and it would be advantageous to select genotypes with greater capacity to store and transfer under water deficit conditions.