Iranian Journal Pulses Research

Abstract Introduction Chickpea is one of the most important legumes in Iran. Despite the abundance of cultivated lands in Iran by chickpea, yield per hectare is considerably lower than world average. Environment conditions of chickpea cultivation in infertile, arid and semiarid regions limit the yield production in Iran. Salt stress, resulted from salts accumulation in soil solution is one the limiting factors for chickpea cultivation in arid and semiarid areas. Chickpea is a salt sensitive plant and yield loss is one of the most potential impacts of salinity on chickpea. Polyamines are low molecular weight polycationic molecules, which play important roles in a number of plant physiological processes, including resistance to various stresses. Recently, the role of polyamines, unique polycationic metabolite, was proved as a regulator of growth and plant membrane transport. They also act as a source of reactive oxygen species (ROS) and ROS scavenger and activator of key antioxidant enzymes. Moreover, they are involved in plant stress tolerance. The present study was conducted to investigate the ameliorating effect of spermine and spermidine spraying on yield and yield components of salt treated chickpea plants.   Materials & Methods The experiment was performed as factorial based on a randomized complete block design with three replications in research farm of Khartooran Shahrood (salinity 5.7 dS m^-1). Spermine was sprayed at three levels (0 (control), 0.25 and 0.50 mM) and spermidine also at three levels (0 (control), 0.25 and 0.50 mM) in three stages including four-leaf, flowering and pod-filling stages. Some attributes such as relative water content, membrane stability index and activity of catalase, polyphenol oxidase and guaiacol peroxidase enzymes, plant height, number of branches per plant, number of pods per plant, number of seeds per pod and seed yield were measured.   Results & Discussion The results showed that foliar spray of spermine at the concentration of 0.50 mM increased membrane stability index (15%) and plant height (23%) in comparison with the unsprayed plants. Moreover, foliar spray of spermidine at the concentration of 0.50 mM significantly increased membrane stability index (17%), plant height (31%), number of branches (52%), number of pods per plant (27%), 100- seed weight (16%) and seed yield (15%), when compared to unsprayed plants. Sodium chloride treatment disturbs membrane integrity and leads to ionic imbalances in plants. On the other hand, polyamines as one of the most important growth regulators, play key roles in regulating membrane functions by attachment to anionic sites or to the negatively charged phospholipid head groups on membranes. Their exogenous consumption probably not only reduces absorption of hazardous ions such as Na⁺ and Cl^-, disturbing normal functions of plant cells and reducing growth, but also protect membranes against the stress injuries caused by salt stress. Furthermore, polyamines are able to reverse the inhibitory effect of salinity stress on plant growth by increasing cell division and cell size. Salt stress declines nutrients transportation to growing shoots and also reduces chlorophyll contents which both leads to growth reduction in plants, while polyamines not only accumulate in thylakoid membranes and increase their integrity under stress but also leads to chlorophyll maintenance and by increasing cell division in root tips elevates nutrient absorption and help plants to keep normal growth. Nutrient and carbohydrate deficiency under saline stress is one of probable reasons for abscission of flowers and branch reduction leading to yield reduction which all can be reversed by exogenous polyamine application. Concerning relative water content (RWC) and enzymes activity, interaction of spermine and spermidine had significant effects on RWC and activity of polyphenol oxidase, catalase and guaiacol peroxidase enzymes. ROS scavenging will reduce their major impact on damages to the biomolecules such as membrane lipids, proteins, chloroplast pigments, enzymes and nucleic acids. Polyamines can act as osmoprotectants to increase water absorption under deficit water condition. They also act as ROS scavenger and activator of key ROS scavenging enzymes.   Conclusion In general, foliar spraying with spermidine was more effective than spermine in mitigating the deleterious effects of salt stress and maintaining the different characteristics of chickpea. Furthermore, application of the concentration of 0.50 mM of both polyamines was more effective than 0.25 mM.

Abstract Introduction
Chickpea is one of the pulse crops and its protein percent is about 22 to 24 percent. Therefore it plays an important nutritional role in human being diet. All plants, including chickpea, experience physiological changes and decreased growth while facing water deficit. Change in photosynthetic electron transport under low-irrigation conditions is one of the factors causing formation of reactive oxygen species (free radicals) including oxygen peroxide, super oxide and hydroxyl (oxidative stress). These free radicals are mainly produced in chloroplast, mitochondrion, and peroxisomes which could inflict destructive and harmful effects on plant cells. In stressed plants, the endogenous polyamine compounds are increased which is mainly a defensive response of plant to oxidative stress. Polyamines are aliphatic hydrocarbons with low molecular weight, straight chain of 3 to 15 carbons, which arginine and ornithine amino acids are their precursor. There are two major biosynthetic pathways for putrescine including ornithine decarboxylase and arginine decarboxylase. After putrescine synthesis, the larger polyamines (spermidine) are synthesized. This process is catalyzed by spermidine synthase through consecutively adding aminopropyl groups to putrescine. This experiment aimed to study the possibility of decreasing harmful effects of low-irrigation on growth and yield of chickpea through spermidine spraying.
 
Materials & Methods
This study was carried out as split plot based on complete blocks design with three replications in research farm of Shahrood University of Technology in 2016 in which the chickpea was sown in June as a secondary planting. The experimental treatments were irrigation regimes (distributed in main plots) in three levels (control (the conventional irrigation; 7-day interval irrigation), 10-day interval irrigation, and 13-day interval irrigation) and spermidine spraying in three levels (control (spraying of water on plant), concentration of 0.3 and 0.6 mM) at 4-leaf, flowering and milky stages. The studied traits were biomass, grain yield, number of pods per plant, grain protein percent, chlorophyll content and activities of catalase and guaiacol peroxidase enzymes.
 
Results & Discussions
The results indicated that under 13-day interval irrigation conditions, the activity of guaiacol peroxidase decreased with increasing concentration of spermidine (About 0.07 µM/min.g fw for 0.1 mM increase in spermidine concentration). No significant difference was found between zero (control) and 0.6 mM in terms of catalase enzyme; these spermidine levels appeared to have the highest activity of catalase enzyme. Under 10-day interval irrigation conditions, the catalase activity amount was statistically similar to its activity under control conditions. However, under 13-day interval irrigation conditions, the activity of mentioned enzyme was almost 80% higher than control. The linear decrease of guaiacol peroxidase activity with increasing spermidine concentration under 13-day interval irrigation conditions and also decrease in catalase enzyme activity under spraying plant with 0.3 mM spermidine may confirms the previous reports regarding the capability of polyamine compounds in direct elimination of free radicals and promoting stability and conserving the membrane. The experimental evidences have indicated that the application of exogenous potrisine has increased the polyamines amount in thylakoid membranes; these results have also been repeated by application of exogenous spermidine. Under 13-day interval irrigation conditions, the relative leaf chlorophyll content appeared to be linearly increased with enhancing the spermidine concentration (One Spad value for 0.1 mM increase in spermidine concentration). In each irrigation regimes, the number of pod per plant was proportionally increased with increasing spermidine concentration (Averagely, about one pod per plant for 0.1 mM increase in spermidine concentration). In each irrigation regimes, the biomass and grain yield were proportionally increased with increasing spermidine concentration (For 0.1 mM increase in spermidine concentration, the average increase in biomas and grain yield was about 72 and 31 Kg/ha, respectively), which proves that spermidine alleviates the harmful effects of low-irrigation. The 0.6 mM spermidine could alleviate the harmful impacts of 10- and 13-day irrigation regimes on grain yield by 20% and 34%, respectively. Proportional to spermidine concentration, grain protein content got increased (About one percent for 0.1 mM increase in spermidine concentration). So that for 0.3 and 0.6 mM spermidine concentrations, the grain protein content was higher than control by 3% and 6%, respectively.
Conclusion
The results indicated that imposing low-irrigation stress affected all measured traits. The application of spermidine polyamine at three stages of 4-loaf, flowering and milky stages caused some changes in activity of antioxidant enzymes catalase and guaiacol peroxidase. These changes took place along with increasing chlorophyll content and number of pod per plant (decreasing flower abortion and enhancing fertile flowers). The changes in the mentioned traits were some of the reasons for spermidine-resulted alleviating the negative effects of low-irrigation on growth and grain yield of chickpea. The 0.6 mM spermidine was found to be the best treatment level for both drought stress and no drought stress conditions.

Abstract Introduction The mechanism of seed priming is to initiate the repairing system for membrane and the metabolic preparation for germination through controlling water absorption rate of seed. As a result, the germination capability and resistance to unfavorable conditions of seed can be promoted obviously. Ultrasound is defined as acoustic waves at frequencies greater than 20 kHz that can be an effective method of improve germination and growth characteristics of plants. Mirshekari et al. (2013) found that treating common narrow seeds with ultrasonic irradiation increases its germination and primary growth. There is no knowledge about the effect of ultrasonic waves and seed priming on plant competition with weeds. Thus, the objective of this research was to study the effect of ultrasonic waves and seed priming on yield and yield components of cowpea (Vigna sinensis L.) in competition with weeds. Materials and Methods Experiment was conducted at the research field of Shahrood University of Technology (latitude of 36° 25 'N and longitude of 54° 57' E with an elevation of 1345 m) as randomized complete block design with four replications in during the growing season of 2013-2014. Treatments included; ultrasonic waves (ultrasound) + no weeding, ultrasonic waves + weeding (all season), ultrasonic waves + reduced herbicide dose (trifluralin 1 L.ha-1), ultrasonic waves + the recommended herbicide dose (2 L.ha-1), hydro-priming + no weeding, hydro-priming + weeding, hydro-priming + reduced herbicide dose, hydro-priming + recommended herbicide dose, no weeding, weeding (all season), recommended herbicide dose, and reduced herbicide dose. In hydro-priming treatment, seeds were treated with water before sowing for 7 hours. Also for ultrasonic treatment, the seeds before sonication (for 6 minutes) treated with water for 7 hour. Trifluralin used in recommended dose (2 L.ha-1) and reduced herbicide dose (1 L.ha-1), therefore immediate mixed with soil before planting. Statistical analyses of data were performed with statistical software MSTATC. Significant differences between means refer to the probability level of 0.05 by LSD test. Results and Discussion The results showed that all treatments decreased significantly biomass and density of weeds in comparison to control (no weeding). No significant difference was observed in density and shoot biomass of weeds between the application of hydro-priming + trifluralin 1 L.ha-1 and ultrasonic waves + trifluralin 1 L.ha-1 with trifluralin 2 L.ha-1 treatment. Hydro-priming + reduced herbicide dose and ultrasonic waves + reduced herbicide dose treatments decreased total weed biomass by 61 and 46.5% in comparison to using reduced herbicide dose treatment. In this regard Abbasdokht et al (2012) reported that density and shoot biomass of weeds was similar between reduced herbicide dose (Nicosulfuron 40 g.a.i. ha-1) + hydro priming and recommended herbicide dose (Nicosulfuron 80 g.a.i. ha-1). During priming, seeds are partially hydrated so that pre-germinative metabolic activities proceed, while radicle protrusion is prevented, then are dried back to the original moisture level (McDonald, 2000). Ghassemi-Golezani et al, (2008) suggested hydropriming as a simple and effective method for improving seed germination and seedling emergence of lentil in the field. Also the results indicated that the combined use of ultrasonic waves + weeding (all season) treatment increased grain and biological yield by 62 and 52.3 percent in comparison to control (no weeding) treatment respectively. Rajabian (2013) reported that seed pretreatment of corn by ultrasonic waves increased the grain and biologic yield in comparison to control significantly. The results indicated that no significant difference was observed in grain yield between the application of hydro-priming + trifluralin 1 L.ha-1 and ultrasonic waves + trifluralin 1 L.ha-1 in comparison to trifluralin 2 L.ha-1 and weeding (all season) treatments. Whereas, sowing pretreated seeds by ultrasonic waves and hydro-priming in soil containing recommended trifluralin dose decreased the investigated traits in comparison to application of pre-treatments alone and recommended herbicide dose. In this regard, Moradbeygi and Khara (2011) observed a significant reduction due to increased trifluralin concentrations on root and shoot length and dry weight of sunflower plants. Based on Yaldagard et al, (2008), one of the possible explanations could be that the mechanical effects of ultra-sonication produced numerous small holes in the coating and after steeping in the water a significant rise in seedling moisture resulted. It has been suggested that the sonication process accelerates the imbibition of water through the pericarp. Sonication may create or enlarge fissures in the protective coating surrounding the seed and pericarp. The superiority of sonication may be due to a higher holding capacity and higher porosity, which increase oxygen availability. Generally it seems that pre-treatment of cowpea seeds by hydro-priming and ultrasonic waves can increase competitiveness of bean plant with weeds through increasing crop growth rate. The results showed that proper combination of trifluralin herbicide along with seed priming could be used to control the weeds in the bean and obtain seed yield comparable with weed-free conditions. Conclusion Both hydro-priming and ultrasonic waves had the effects on accelerating germination and improving competitive ability of bean plant. Hydro- or ultrasonic waves priming showed better plant growth than that without priming treatment when exposed to competition conditions. Pretreated seeds in combination to low herbicide dose had the best effects on the weed suppression and increasing crop yield. Based on our results, priming and sonication of seeds in combination with reduced dose of herbicide can be an effective method of weeds control and increase crop yield and also reduce herbicide consumption.