نشریه پژوهش های به زراعی
سال یازدهم شماره 4 (زمستان 1398)

In order to investigate the effect of foliar application of seaweed extract on yield and yield components of Cotton under salinity stress, a factorial experiment in a randomized complete block design with three replications was conducted in Sabzevar Agricultural and Natural Resources Research Center in 2017. The experimental factors included application rate of seaweed extract at four levels of 0, 2, 4, and 6 ‰ and foliar application time at two levels at the vegetative and vegetative+flowering stage. The results showed that the time of seaweed extract application had no effect on the number of sympodial branches, the number of bolls, boll weight and grain yield, while foliar application of seaweed extract at vegetative + flowering increased the final height, lint percent, cotton seed yield and fiber yield. Foliar application at a concentration of 6 ‰ of seaweed extracts increased 31.19% in height, 32.19% in sympodial branches, 41.44 in boll, 23.25% in boll weight, 41.43% seed cotton yield, 61.43%, seed yield, 29.66%, fiber yield and 42.34% lint percent, In general, the results of this experiment showed that two times foliar application of seaweed extract at level 6 per thousand in vegetative and flowering stages were recommended for producing maximum yield and yield components of cotton under salt stress conditions.

In order to study changes of agronomic traits under drought stress and identification of tolerant germplasm, a total of 484 accessions of bread wheat collection of National Plant Gene Bank were studied in Yazd field under normal and drought stress conditions by planting tolerant cultivars (Kavir, Roshan and Mahooti). Drought stress was applied by irrigation stoppage after cultivation. Evaluation of agronomic traits was carried out in accordance with international descriptor both for 71 drought survived accessions and the same accessions under normal condition. Analysis of descriptive statistics showed that the grain weight of five spikes under normal condition and the number of fertile tillers under drought stress had the highest coefficient of variation. The highest mean reduction in traits under drought stress was observed for grain weight of five spikes (23.8%) and then for the number of fertile tillers (21.1%). In almost all traits evaluated, some accessions were superior to control cultivars in both normal and drought conditions. Grain weight of five spikes under drought stress was significantly correlated with florets number per spikelet (r = 0.272*), grain number per spike (r = 0.742**), one-hundred-grain weight (r = 0.663**), grain filling period (r = 0.314**) and days to spike emergence (r = -0.238*). The accessions were divided into four groups under drought stress and normal conditions using cluster analysis dendrogram. Distinction among clusters was confirmed by discriminant analysis. The superior accessions identified in this study can be used in drought tolerance wheat breeding programs.

In order to determine the susceptible and tolerant lines of sunflower to drought stress, a completely randomized block design with three replications was conducted at Karaj seed Oil Research Institute. In this study, 12 different sunflower lines have been identified for the characteristics related to drought tolerance and were selected two susceptible and tolerant lines. Initially, sunflower lines were cultivated in two separate experiments under normal irrigation and drought stress conditions. Drought stress was carried out through stop irrigation in step 2 to 8 leaves formation. The studied traits included agronomic characteristics and drought stress indices of sunflower, such as Plant height, Stem diameter, Head diameter, Seed yield, Leaf Area Index, Relative Water Content, SSI and STI. The studied traits were significantly different in water stress, except stem diameter. After analyzing the tested factors and analyzing the data, the results were obtained by analyzing the percentage of variation of studied traits, calculating stress indices (drought tolerance indices, drought sensitivity) and dendrogram drawing from Cluster analysis of cultivars was identified. According to the results, in terms of water deficit stress, RGK26 and RGK41 produced the highest and the lowest seed yield per plant. Comparison of traits can identify BGK221 as susceptible line and RGK46 as tolerant line among 12 studied lines. Also, correlation between traits showed that drought tolerance index (STI) was positively correlated with almost all traits. In addition, grain yield was positively correlated with all traits except plant height.

Due to analyze the correlation and regression of agronomic traits (grain dimensions) with grain yield of two peanut cultivars under irrigation management conditions (water requirement) and plant mulch an experiment was done as factorial split plots based on completely randomized blocks design with 3 replications during 2019 in Astaneh Ashrafieh. The irrigation management in 3 three levels (no irrigation (rainfed), 50 and 100% of plant water requirement) as main factor and mulch application in 3 levels (0, 2 and 4 cm) and peanut cultivars in two levels (Guil and Gorgani) were considered as sub factor. The results showed that the interaction between irrigation and mulch had the highest seed yield in 100% of water requirement and 4cm of mulch application (2775 kg ha-1). The plant height at 100% of water requirement was 73.8cm which showed 13.7% and 7.7% increase than irrigation conditions and 50% of water requirement respectively. The highest plant height was obtained in 4 cm mulch treatment (75.5cm). In irrigation management, the highest seed length was obtained in 100% water requirement (2.4cm) and 4 cm mulch (2.4cm). The highest seed width was observed in 100% water requirement (1.2 cm), 4 cm mulch application (1.2 cm) and Guil cultivar (1.2cm). Seed yield was positively and significantly correlated (0.788**) with seed length. It can be concluded that with higher seed length, greater seed yield will be observed. Overall, water stress decreased yield and mulch application reduced the negative effects of water stress on both Guil and Gorgani cultivars. Guil cultivar showed higher resistance to waterdeficit stress compared to Gorgani cultivar.

During past centuries and industrial activities of human that have been include of agriculture, military and disposal of industrial wastes caused that wide region specially, developed countries face with high concentrations of heavy metals and pollutants. Moreover, negative effects on ecosystems and other natural regions, these regions created too many risks for human health because of food pollution by usage of agricultural productions and drinking water. The aim of this research, discussion about phytoremediation with use of local techniques and those potentials is as a corrective technique that from natural capability of biotic plants use for removal and purification of pollutant components of environment. This research was done as completely randomized blocks design with 3 replications during 2011for evaluation of efficiency amount and amplitude of usage of herbal exploitation method by offensive plant Chrozophora tinctoria for purification of around solis of Iralko complex. At first Zn, Ni and Cr elements measured in soil, then in the control treatments, 2.5, 5 and 10 fold of sample mean concentration, the amount of uptake and storage in different plant organs were investigated. The results showed that the highest amount of Zn (61.63%) and Chromium (67.33%) were found in leaf and stem, respectively. According to the results, it can be stated that Chrozophora tinctoria have an effective role in the removal of Zn and Cr in the complex surrounding soils.

Usually sowing date and harvest time of summer crops such as maize have a significant impact on the quantitative and qualitative yield of the crop. Therefore, the aim of this study was to investigate the effect of sowing date and harvest time on quantitative traits and yield of silage maize (single cross 701; cv. Karun), this experiment was done as a split plot based on completely randomized blocks design with three replications in Varamin at year of 2015. Treatments included five sowing dates as main factor (9th of April, 21th of May, 18th of June, 30th of June and 15th of July) and two harvesting times as sub-factor (grain milky stage and grain dough stage). The results showed that the effect of sowing date had significant effect at 1% level on the stem fresh weight, maize fresh weight, total fresh weight, stem fresh weight to total fresh weight ratio, maize fresh weight to total fresh weight ratio and fresh forage yield and significant effect at 5% level on the leaf fresh weight to total fresh weight ratio. Based on the findings sowing date of 30th of June has more fresh weight of leaf, stem and ear and more fresh forage than other sowing dates. Harvesting time in milking stage has better quality and harvesting at dough stage has higher quantity of product. Correlation between studied traits showed positive and high effect of stem fresh weight with forage yield. In general, it can be stated that summer sowing dates, especially 30th of June and harvest time at the dough stage are the most favorable times for silage corn cultivation in the Varamin region.