نشریه فیزیولوژی محیطی گیاهی
پیاپی 46 (تابستان 1396)

To study the response of grain yield, chlorophyll (a) content, glycine betaine, proline, soluble sugars, total phenolics, and catalase (CAT) activity in maize hybrids to drought stress during kernel filling stage, a field experiment was carried out as a split plot completely randomized block design with four replications in Moghan Research Station, during 2010 and 2011 growing seasons. The main plots were composed of two drought stress levels including commonly available irrigation water (control) and no irrigation at kernel filling stage. Three maize hybrids including NS640, SC704, and SC720 were allocated into sub-plots. Analysis of the data suggested that drought stress significantly affected all measured characters and reduced grain yield (30.7%) and chlorophyll (a) content (14.7%). Drought stress also increased glycine betaine, proline, soluble sugars, total phenolics, and CAT activity about 30.2, 36.7, 17.8, 38.8 and %15.2, respectively. SC704 displayed maximum grain yield and osmolyte accumulation. Based on the findings of the study, grain yield, chlorophyll (a) content, glycine betaine, proline, soluble sugars, total phenolics, and catalase (CAT) activity can be used to study drought-response and drought-tolerance of maize hybrids.

This study was carried out for evaluation of the effects of drought stress after anthesis on agronomic characteristics and some physiological responses of flag leaves and spicules of different wheat genotypes using a factorial experiment in a randomized complete block design with two factors (irrigation and wheat genotypes) and three replicates. Two levels of irrigation involving control (full irrigated under water farming conditions) and drought stress (irrigation cut after anthesis until the end of growth period) as the first factor and different wheat genotypes (TEVEES'//CROW/VEE'S and Shark: drought sensitive, Manning/Sdv1/Dogu8 and Sabalan: semi tolerant, Sardari HR-86 and Dogu88/Ghafghaz 7: tolerant to drought stress) as the second factor were considered and agronomic and physiological characters were measured. Drought stress decreased grain yield through decreasing 1000 grains weight. Manning/Sdv1/Dogu8 semi tolerant genotype showed the highest and Shark genotype showed the lowest grain yields. Results showed that soluble protein content increased in flag leaves and spicules under stress compared to control. Sardari HR-86 and Shark genotypes showed the highest and lowest soluble protein content in flag leaves, respectively. The highest and lowest soluble protein contents in spicules were observed in Manning/Sdv1/Dogu8 and Shark genotypes, respectively. The study also showed that peroxidase, ascorbate peroxidase, and superoxide dismutase enzymes activities increased under drought. The highest enzyme activity was observed in flag leaves of Sardari HR-86 tolerant genotype and in spicules of Manning/Sdv1/Dogu8 semi tolerant genotype in the last step of sampling. Also, sensitive genotypes showed the lowest enzyme activities. Based on the obtained results it seems that in Manning/Sdv1/Dogu8 semi tolerant genotype, activation defense system of peroxidase and superoxide dismutase enzymes had a key role in improving tolerance to drought stress.

This study was performed to investigate the effect of applying olive (Olea europaea L.) pomace on some physiological characteristics and grain yield of three cultivars of rice (Oryza sativa L.). A pot experiment was used based on a completely randomized factorial design with three replications. Five levels of olive fruit pomace (0, 1, 3, 5, and 7% w/w) were applied to three rice cultivars of Champa, Danial, and Red Anbouri. After full growth and maturity of rice, grain soluble carbohydrate content, shoot proline content, mean panicle weight, main grain number per panicle, 1000 grain weight, panicle harvest index, grain yield, 1000-grain, and the biomass were measured. Also, the amount of K, P, N, and Zn in the different treatments of olive fruit pomace was measured. The results showed that application of olive pomace caused a significant increase in the characteristics under investigation compared to control. Under study treatments, growth indices improved at 5% w/w. The possible reason for this could be the existence of elements effective on plant growth in pomace treatments.

Compost fertilizer because of containing abundant nutrients, high capacity for holding water, plant growth regulators and helpful microorganisms can improve soil physicochemical characteristics and play an effective role in plant growth and development. In order to evaluate the effects of compost fertilizer on morpho-physiological indices of lentil under water deficit stress, a factorial experiment was conducted in a natural environment and with three replications based on a completely randomized design in the Khatam Alanbia University of Behbahan. The experiment treatments consisted of five ratios of compost fertilizer and soil (0:100, 5:95, 15:85, 25:75, and 35:65) and three levels of water stress inclding no stress, moderate stress, and severe stress (irrigation at 25, 50, and %75 of field capacity, respectively). Results showed that there were significant differences in all traits under different compost fertilizer and water stress levels. The findings also showed that under no stress and moderate water stress conditions, application of a mixture of compost and soil at %25 and %35 weight, resulted in a significant increase in the plant height, leaf area, leaf number, root dry weight, root length, root area, and Chlorophyll a and a/b ratio compared to the control levels. Under severe water stress, application of compost at 35% level led to a significant increase in the number of leaves, leaf area, root length, and Chlorophyll a content. Therefore, the use of a mixture of compost and soil (especially 35:65 ratio) is recommended to improve the morpho-physiological characteristics and yield componentsof lentil under moderate (or severe) water stress conditions.

It is estimated that 20 to 25 percent of all turfgrasses are maintained under some shades, whether from building or trees. Shade affects plant growth by influencing light intensity, quality, and duration. Given the importance of turfgrasses in the beauty of the environment surrounding human beings, so far enough research has not been done to understand the morpho-physiological properties of the turfgrasses under different day length conditions. For this purpose, a field experiment was conducted to determine the effect of day length on some morphological and physiological characteristics of two turfgrass genera in a split plot study based on a randomized complete block design with four replications in research farm of the Department of Horticultural Sciences, College of Agriculture, Shiraz University. Day length at three levels including long day length (16 hours), intermediate day length (12 hours), and short day length (8 hours) were considered as the main factor and two turfgrasses genera (Festuca arundinacea Schreb. and Cynodon dactylon [L.] Pers.) were considered as sub plots. The results showed that short day causes decreasing tiller density, fresh and dry weight of shoot, fresh and dry weight of root, and chlorophyll and starch contents and led to increasing leaf area and superoxide dismutase, peroxidase, and ascorbate peroxidase enzymes activities. Also, results showed that long day causes increasing tiller density, fresh and dry weight of shoot, fresh and dry weight of root and chlorophyll and starch contents and led to decreasing leaf area and superoxide dismutase, peroxidase and ascorbate peroxidase enzymes activities. Festuca arundinacea turfgrass compared with Cynodon dactylon turfgrass showed more resistance to decrease in day length. Regarding the possibility of increasing the period of light in parks and stadiums, in cold seasons when turfgrasses turn yellow, increasing photoperiod leads to improvement of the green color and increasing the efficiency of turfgrasses.

Cyanobacteria are gram-negative photosynthetic microorganisms. Because they contain a variety of chemical compounds such as pigments, vitamins, and enzymes, theses microorganisms have found many applications in the industry. Several studies have reported that cyanobacteria can improve the plant growth by improving the soil structure as they have potential to secrete extracellular polysaccharides that help in soil aggregation and water retention. Numerous plant-associated bacteria produce auxin and related indolic compounds. The role of microorganisms as plant growth stimulators is widespread in nature, especially in relation to the production of phytohormones. Auxins represent a group of plant hormones that are implicated in the regulation of diverse biological processes. The aim of this research was to study the production capability of auxin and some photosynthesis pigments in heterocystous cyanobacteria serovars isolated from paddy fields in eastern part of Mazandaran. After collecting soil samples, cyanobacteria cultures were cultivated on a typical BG110 medium, for purification purposes, repeated sub-culturing was carried out on solidified and liquid medium before the strains were characterized morphologically. Results indicated that a great range of isolated cyanobacteria had the potential to produce auxin as a main factor for improving plant growth and there were significant differences in the chlorophyll and carotenoid contents; however, potential of each species according to different ecological diversity and genus were different. Maximum chlorophyll, carotenoid, and auxin contents were observed in MGCY277 (Lyngbya diguetii), MGCY497 (Nostoc ellipsosporum), and MGCY358 (A nabaena variabilis) serovars, respectively.

Numerous biochemical and molecular mechanisms have been developed in plants to fight against salt stress namely, change in the content of osmolytes, enhancement of phenolic compounds, and supporting photosynthetic activity. These mechanisms lead to products and processes which improve the tolerance to salinity. Since there is no significant research on the resistance mechanisms of the species Salsola dendroides pall and Limonium reniforme (Girard) Lincz., some of these physiological changes in the aforementioned plants were investigated under natural stresses during different seasons to study their tolerance mechanism. To this end, plants were randomly collected from Incheboron area, north of Gorgan with four replicates during spring, summer, and autumn. Results showed that with increased temperature and salinity in summer, chlorophyll pigment contents significantly decreased in both Salsola dendroides and Limonium reniforme species. Soluble sugars content significantly increased in shoots and roots of Salsola dendroides in spring compared with other seasons while soluble sugars content in Limonium reniforme was higher in summer in comparison with spring. In summer, flavonoid contents significantly increased in shoots and roots of both species compared with other seasons. Anthocyanin content significantly changed with the change in seasons, while the highest anthocyanin contents were observed in shoots and roots of Salsola dendroides and Limonium reniforme in summer and autumn, respectively. Most of these changes were associated with activation of physiological and biochemical processes which allow the plants to adapt to saline conditions.

Piriformospora indica fungi stimulates the growth and increase in the host biomass through absorption of water and minerals. In order to evaluate the effect of mycorrhizal fungus P. indica on growth and some physiological parameters of Coriandrum sativum, an experiment was conducted in a randomized complete block design through treatment of plants inoculated with mycorrhizal fungi and control plants with 15 replications in 2015 under greenhouse conditions.The results of ANOVA indicated that the shoot length, root length, and dry weight of plants inoculated with fungi were significantly higher than control plants. Also results of analysis of variance showed that the application of P. indica increased the proline content, so that the proline content in the plants inoculated with mycorrhizal fungi was 2.09 times higher than control plants. In addition, the findings of the study suggested that inoculation of the plant with P. indica increased the contents of chlorophyll a (17%), chlorophyll b (51%), and carotenoids (25%) in comparison with the control plant, where the increase was only significant in chlorophyll b and carotenoids (P≤0.05). Generally, the results indicated that mycorrhizal symbiosis increased the growth and improved the physiological characteristics of coriander.