نشریه فیزیولوژی گیاهان زراعی
پیاپی 43 (پاییز 1398)

In order to effect study and comparison of exogenous application of individual and combined hormonal treatments of kinetin and 24-epibrassinolide on some biochemical traits and weight of thousand grains in three wheat cultivars with different tolerance to water deficit period including Pishtaz (tolerant), Sabalan (semi-tolerant) and Gaspard (susceptible)  under drought stress during booting origin, the pot experiment as factorial design with four replications was conducted in Yazd university in 2015. Therefore, treatments included factors of cultivar in three levels, drought stress in two levels (field capacity of 100% or control and 50% or drought stress)    and hormones applications in four levels of non-hormone, kinetin (100 µm), 24-epibrassinolide (1 µm) and their interaction. The flag leaves were applied for analysis. Drought exposure resulted to the most reduction of chlorophyll a, b, a+b, a/b ratio, carotenoid, and weight of thousand grains in susceptible cultivar (Gaspard). The highest significant increment of abscisic acid, soluble sugar, proline level and soluble sugar/starch ratio were observed in tolerant cultivar. 24-epibrassinolide resulted to the most significant increasing of abscisic acid and soluble sugar/starch ratio and kinetin and 24-epibrassinolide combination caused the highest increment of pigment, proline and protein content and also weight of thousand grains during drought exposure in tolerant cultivar (Pishtaz), especially. Results of this research showed that influence of hormonal treatment on chemical treatment was more than their effect on weight of thousand grains. Kinetin and 24-epibrassinolide combination resulted to more influence than individual treatment of hormones on chemical traits and weight of thousand grains. Pishtaz cultivar (tolerant) was benefited from hormonal treatments in related to tolerance of water deficit.

Considering the necessity of saving water resources, to study new cultivars of maize to reduce the negative effects of water scarcity, the split-plot in the (RCBD) design with three replications was conducted at Research Field of Islamic Azad University, Arak was carried out in the years of 2016 and 2017. The treatments consisted of different levels of irrigation in the main plots, including I1(7-days control), I2(10-days), I3(12-days), I4(14-days) until the end of the course.  Irrigation was cut off during vegetative growth period after planting the seedlings from stage 3-7, and hence, irrigation interval was once applied to I5(10-days), I6(12-days) and I7(14-days). In sub plots, single-cross cultivars were considered in 704, 703,705 and 706 corn. According to the current study, irrigation and corn cultivars had a significant effect on yield and physiological indices. Decreasing irrigation levels resulted in decreased yield, relative water content and chlorophyll content in leaf compared to control treatment. In interactions between irrigation intervals and cultivars, I1 to I3 irrigation intervals showed cultivar 703 with the highest average maintenance power and growth indices, while in the irrigation interval from I4 to I7, single cross 705 varieties were superior to other cultivars shows. In all irrigation intervals single- cross 704 with the least power was recorded compared to other cultivars. The highest water use efficiency on cultivar 705 was at irrigation interval I5 with 39.54% superiority than to control irrigation and cultivar 704.

In order to study the effects of nitrogen fertilizer and growth regulator of cycocel on nitrogen use efficiency, some physiological traits and grain yield of rice (Oryza sativa L.), a factorial experiment was conducted based on randomized complete block design with three replications at the farm of Someasaraye from Gilan Provence during 2014-15. Treatments were included nitrogen rates in four levels (without nitrogen application as control (N0) and application 100 (N1), 150 (N2) and 200 (N3) kg N ha-1 as urea) and four cycocel levels (without cycocel as control (C0), application of 0.8 (C1), 1.6 (C2), 2.4 (C3) L ha-1). The results showed that foliar application of 2.4 L ha-1  cycocel and 200 kg N ha-1 increased grain filling rate, grain filling period, effective grain filling period, the number of grains per ear and 1000 grains weight. The highest dry matter remobilization from shoots and stem (114.6 and 57.91 g.m-2  respectively) and the highest dry matter from shoots and stem reserves contribution to grain yield (47.91% and 27.04%, respectively) were obtained  without  nitrogen application and foliar application of 2.4 L ha-1 cycocel. The highest grain yield was obtained in application of 200 kg N ha-1 and the lowest it belongs to no nitrogen application. The highest nitrogen use efficiency was obtained in application of 100 kg N ha-1 and the lowest it belongs to 200 kg N ha-1. The highest nitrogen use efficiency was obtained in application of 2.4 L ha-1 cycocel and the lowest it belongs to no cycocel application. Foliar application of 0.8, 1.6 and 2.4 L ha-1 cycocel increased 12.47%, 21.68% and 32.05% from grain yield respectively in compared with control. It seems that foliar application 2.4 L ha-1 cycocel and application of 200 kg N ha-1 can be as a proper tool for increasing grain yield of rice.

Selenium is a non-metallic element that has an effect on the growth and development of plants and, due to its presence in antioxidant systems, improves the growth and physiological traits of plants. For this purpose, an experiment was conducted based on a randomized complete block design with split-plot split plot with three replications during two years of cultivation 2014-15 and 2015-16 in research farm of Seed and Plant Improvement Research Institute, Karaj, Iran. Selenium spraying (from sodium selenate source) in main plots in two levels of control (without spraying) and spraying 30 g/L in two stage  in pre-flowering and six genotypes of autumn rapeseed in sub plots were compared. The effect of year, selenium spraying, and genotype were significant on proline content, soluble carbohydrate, photosynthetic pigmentation, selenium content, seed oil and grain yield. Application of selenium resulted in increased proline (6.68%), carbohydrate (7.26%), chlorophyll a (8.65%), total chlorophyll (7.44%), selenium grain (79.87%), seed oil (0.89%), and grain yield (8.1%) compared to the control treatment. The proline content of leaf in 2014-15 year was significantly higher and equal to 69.63% more than in 2015-16 year. The highest oil content and grain yield were observed in SW102 genotype with average of 7.47% and 2060.6 kg/ha, respectively. Generally, the results showed that cultivating SW102 and Elvis genotypes under selinum sparying conditions caused the optimal content of oil and grain yield, which is recommended for the area under test.

In order to investigate the effect of iron and zinc chemical fertilizer and nano-Chelate foliar on on chlorophyll concentration, radiation use efficiency and grain yield of two bread wheat cultivars, an experiment was carried out as a factorial based on a randomized complete block design with three replications at the Zarinabad Agricultural Research Center, Ilam, during in 2016-2017. The factors consisted of spraying in seven levels (control, spraying with iron chelate, iron nano chelate, zinc sulfate, zinc nano chelate, iron chelate + zinc sulfate and iron nano chelate + zinc nano chelate) and the second factor of two wheat cultivars (Chamran and Koohdasht) was. The results showed that spraying with iron fertilizers and zinc sulfate had a significant effect on chlorophyll concentration and maximum leaf area index at 1% and 5% probability levels, respectively. The maximum leaf area index at the level of 1% in Koohdasht cultivar was 7.21% higher than Chamran cultivar. Spraying with nano-chelates of iron with nano chelate has reached the maximum dry matter accumulation (782 g.m-2). The least trait was obtained at 681 g.m-2 in control plants (non-spraying). In Chamran cultivar, the maximum amount of radiation use efficiency was 2.30 g.MJ with the use of iron nano chelate, which was 10.27% more than control plant. The highest amount of light consumption in Koohdasht cultivar (2.45 g.MJ) under zinc sulfate + iron chelate and its lowest value (2.8 g.MJ) was obtained in control plants. Spraying with nano chelate on zinc + nano chelate of iron and iron chelate + zinc sulfate increased the grain yield of wheat cultivar Chamran by 27.44 and 15.95 percent, respectively, compared to control treatment. In Koohdasht cultivar, zinc and iron nano chelate had no significant effect on grain wheat agronomy in Koohdasht cultivar.

In order to investigate the effects of water deficit stress and nano-TiO2 foliar application on ear yield and activity of some antioxidant enzymes in sweet corn plant, an experiment was conducted in split plot form based on RCBD in three replications at the Research Station of the Islamic Azad University, Tabriz Branch, during growing seasons of 2017. Treatments were water deficit stress in three levels contained: 50, 75 and 100% filed capacity (FC) as well as the nano-TiO2 foliar application in four levels contains: non application (control), 0.01, 0.03 and 0.05%. The analysis of variance showed significant effect of water deficit stress on catalase (CAT), hydrogen peroxide (H2O2), water relative content (RWC), ear yield (p<0.01) and ascorbate peroxidase (APX) (p<0.05). Also, effect of nano-TiO2 foliar application in all studied traits (p<0.01) and interaction effects between water deficit stress and nano-TiO2 foliar application except for water relative content in other studied traits (p<0.01) was significant. 0.01% Nano-TiO2 increased catalase and ascorbate peroxidase enzymes and decreased hydrogen peroxide in all treatments, however, 0.01% nano-TiO2 foliar application under 50% FC irrigation had the highest activity of catalase, ascorbate peroxidase and lowest levels of hydrogen peroxide. Furthermore, 0/01% nano-TiO2 foliar application under 100% FC irrigation as compared to the non TiO2 foliar application under 50% FC and control increased ear yield by 58 and 8.1%, respectively. Generally, 0.01% nano-TiO2 foliar application under 50% FC irrigation was able to increase the activity of enzymes associated with the reduction of stressful effects and eventually, the yield of the ear was increased in similar conditions and did not use this combination.

In order to evaluate the effect of heat stress and water restriction on grain yield and Components yield of wheat cultivars, this experiment was conducted as split plot based on randomized complete block design with four replications at Khuzestan Agricultural Research Center in two years in (2016-2017). Main plots included control cult that planting on recommended and normal conditions, planting was done on recommended dates, and discontinuation of irrigation after pollination and finally planting with a delay of one month from the recommended planting date and having normal and sub plots consisted of 3 wheat genotypes (Chamran2, Aflak and Khalil). The results showed that Drought and heat stress reduced the yield and its components and Grain filling period is heavily influenced by heat stress for all cultivars. In general, Khalil cultivar with superior grain yield (3582 kg / ha) and 1000 grain weight (34.3 g) was superior to other cultivars under stress of water and heat limitations. Grain yield of Chamran 2 variety was significantly reduced in terms of water restriction and heat stress that in this situation it is not recommended. In comparison with other two cultivars, Khalil cultivar with the highest grain yield and 1000-grain weight was more resistant to stress conditions and suitable for cultivation with such conditions is recommended.

Acidic modifiers are common methods in high pH soils to increase solubility of nutrients. In order to investigate the possibility of reducing the soil alkalinity and increasing the solubility of nutrients, this experiment was conducted based on factorial in a randomized complete block design with three replications.  The factors including three levels of zero, 250 and 500 kg/ha sulfur sulfate and three levels of zero, 5 and 10 kg/ha thiobacillus bio-fertilizer that performed in three replicates in the Elahi village located in north of Ahvaz in 2017-18. The results showed that the effect of sulfur fertilizer and thiobacillus on number of spikes per square meter, grain number per spike, 1000-grain weight, grain yield, biological yield, harvest index and protein percentage were significant at 1% probability level. The interaction between sulfur and thiobacillus fertilizers on biological yield at 1% and harvest index at 5% probability level was significant. The results of mean comparisons showed that grain yield and protein percentage increased with change in thiobacillus and sulfur content and was statistically different at different levels of treatments. The maximum grain yield was obtained from 500 kg/ha sulfur treatment and 10 kg/ha thiobacillus by 5663 and 5077 kg/ha, respectively, while the minimum grain yield was observed under non-application of sulfur by 3668 kg/ha and non-application of thiobacillus by 4329 kg/ha. The maximum protein content was under 500 kg/ha sulfur and 10 kg/ha thiobacillus by 13.2% and 12.7% and the minimum was in non-application of sulfur by 10.8% and non-application of thiobacillus by 11.6%. In general, the results of the experiment showed that under sulfur and thiobacillus application, it is possible to increase the quantitative and qualitative of yield in wheat. In this experiment, the best result was obtained under 500 kg/ha of sulfur and 10 kg/ha of thiobacillus, which could be considered and recommended by farmers and researchers.