جستجوی مقالات مرتبط با کلیدواژه "photosynthesis pigments" در نشریات گروه "زراعت"

Under water stress conditions, intercropping can be used as a strategy for maximum use of sunlight and limited water resources. Due to the difference in morphological and physiological traits, the two plants corn and mung bean may be suitable for intercropping under drought stress; Therefore, this research was conducted with the aim of investigating the effects of drought stress on the physiological traits and yield of corn and mung beans in monocultures and intercropping in order to study the possibility of reducing water consumption in this production system.

An experiment was carried out as a split plot based on randomized complete block design with three replications at Ilam University during 2019-2020 growing season. The main plot were four water regimes including (40, 60, 80, and 100% of the plant's water requirement) and the subplots were include the planting pattern at four levels (additive intercropping series 100% corn + 50% mung bean, replacement intercropping series 50% corn + 50% mung bean and monocultures of mung bean and corn). The application of drought stress started after the establishment stage of the plant and continued until the harvest. At the end of the growth period, some physiological traits of both plants were measured, including photosynthetic pigments, photosynthesis rate, transpiration rate, intercellular CO2 concentration, proline amount, leaf relative water content and grain yield. Finally, analysis of variance (ANOVA) was performed using Minitab 14 and SAS 9.1 softwares and the means compared by HSD test at 5% probability level (p≤0.05).

The results showed the highest rate of photosynthesis (25.4 µmol CO2.m-2.s-1) was obtained in the treatment of 100% water requirement and the lowest rate of photosynthesis was obtained in 40% water requirement, which showed a decrease of 68.5% compared to the well-watered conditions. The rate of photosynthesis of corn in the replacement intercropping of 50% corn + 50% mung bean was 18.3% higher compared to monocultures corn. The highest rate of mung bean photosynthesis was observed in replacement intercropping under conditions of 100% water requirement and additive intercropping series under 80% water requirement, and the lowest rate of mung bean photosynthesis was observed in intercropping under conditions of 60 and 40% water requirement. Dehydration stress decreased the amount of total chlorophyll in mung beans and corn. The highest intercellular CO2 concentration (475.5 mmol of CO2.m-2.s-1) and the temperature of the corn leaf (36.7 °C) belonged to the 40% water requirement treatment. The rate of transpiration of corn and mung bean decreased by 55.56 and 61.43% in the condition of 40% water requirement compared to well-watered conditions. Water stress reduced the relative water content of corn and mung bean. The highest proline in corn and mung leaves (46.3 and 45.23 µmol.g-1.FW-1, respectively) was obtained in the treatment of 40% water requirement, which had no significant difference with 60% water requirement. Corn grain yield in the treatment of 40% water requirement showed a decrease of 52.76% compared to 100% water requirement. Monocultures (3945.8 kg.ha-1) and intercropping (3875.1 kg.ha-1) had the highest corn grain yield, and the lowest corn grain yield in replacement intercropping was 2700 kg ha-1. At all irrigation levels, the highest grain yield of mung bean was obtained in monocultures, and the yield decreased in additive and replacement intercropping, and additive intercropping had the lowest grain yield. The values of land equality ratio of all intercropping patterns were greater than one, which indicates the advantage of corn and mung bean intercropping patterns to use land and increase yield.

Considering the occurrence of recent droughts in arid and semi-arid regions of the country and the need for forage in these regions, the cultivation of forage plants, especially corn, is inevitable. Therefore, one of the appropriate strategies to protection in management and water consumption is the intercropping of this plant with plants of the legume such as mung bean. Intercropping can partially moderate the effects of drought stress on plant water conditions. In general, it seems that the patterns of intercropping and substitution, due to having higher grain yield potential, is a suitable strategy for producing higher yield and stability of this plant compared to monocultural under well-watered and stress water.

Low quality of seeds resulting from seed deterioration is of major concerns underlying reduction in both quality and quantity of production in agricultural sector. Therefore, applying compounds like CA to alleviate seed aging deleterious effects and eventually to ensure final crop yield is important. Effects of five different CA on germination percentage and seed vigor were assessed as a factorial based on completely randomized design in seed lab of plant physiology group in Wageningen University.  Effects of three different concentrations of CA on physiological traits, yield and yield components of cowpea plants from seeds with different primary qualities were assessed in a two-year field experiment as factorial based on completely randomized blocks in three replications. Results indicated that CA had no significant effect on germination of unaged seeds, but concentrations of 15 and 30 µM improved seed vigor. In aged seeds CA pretreatment induced a 13-percent (45 and 60 µM) and 38-peercent (45 µM) in germination and seed vigor, respectively. Assessed characteristics differently responded to CA application based on their primary seed quality. So that when the CA application improved a trait, the trait was reduced in plants of different seed primary quality. In total, CA foliar application in plants from aged seeds was more effective to enhance yield and yield components while the reverse result was obtained for plants from unaged seeds.In case of dry matter accumulation, aged seed pretreatment was more effective than foliar application while a reverse result was obtained for plants from unaged seeds.

Application of methanol foliar on aerial parts of plants increases their yield and accelerates their ripening and also the use of nano-fertilizers for precise control of nutrients release can be an effective step towards achieving sustainable agriculture. In order to evaluate the effect of foliar application of methanol and potash fertilizers on photosynthetic pigments, yield and yield components of wheat (Triticum aestivum L.), a factorial experiment was conducted as a randomized completely blocks design with three replications in 2015-2016 at Research Farm, Ilam University, Ilam, Iran. Factors included three levels of methanol (0), 10 and 15% by volume and three levels of nano-potash fertilizer (0), 2 and 4 per thousand. Results showed that foliar application of methanol had only a significant effect on harvest index. Effect of nano-potash fertilizer on spike per plant was significant. Interaction between nano-potash fertilizer foliar and methanol on grains per spike, plant height, grain yield, chlorophyll and carotenoids was significant, while there was no significant effect on grain weight and biological yield. The highest and the lowest of chlorophyll a, b and total carotenoids contents were found in foliar treatment with 10% methanol and 4 kg nano-potash and control (no application), respectively. The highest grains per spike and grain yield were obtained with 15% methanol and 4 kg nano-potash compared to control treatment (40 and 45 percent), respectively. Overall, results showed that foliar treatment 15% methanol with 4 kg/ha nano-potash could possibly be useful to increase wheat yield.

Drought is undoubtedly one of the most important environmental stresses limiting the productivity of crop plants around the world. It has substantial influence on the growth condition, morphological structure and physiology and biochemistry of plants. Deficit irrigation strategy and planting crops with low water requirements and low expectations, for example, Kochia is very important under drought stress. Kochia is a salt- and drought-tolerant species that can be grown on drought soils, yielding fodder in quantities approaching that produced by alfalfa. Farmers in some arid areas of the world have already begun to cultivate Kochia as a salt-tolerant forage crop on lands where other crops are difficult to grow; accordingly, Kochia has been called ‘‘the poor man’s alfalfa’’.
Drought stress decreases the rate of photosynthesis. Limiting factors in photosynthesis under environmental stresses is the two groups, stomatal limiting factors (Transpiration, stomatal conductance and co2 sub-stomatal) and non- stomatal limiting factors (chlorophyll content, chlorophyll fluorescence and etc.). Plants grown under drought condition have a lower stomatal conductance in order to conserve water. Consequently, CO2 fixation is reduced and photosynthetic rate decreases, resulting in less assimilate production for growth and yield of plants. Diffusive resistance of the stomata to CO2 entry probably is the main factor limiting photosynthesis under drought. Furthermore, drought stress lead to oxidative stress in the plant cell. Drought stress caused a large decline in the chlorophyll a content, the chlorophyll b content, and the total chlorophyll content in most plants. The decrease in chlorophyll under drought stress is mainly the result of damage to chloroplasts caused by active oxygen species. One of the most often employed parameters is maximum quantum yield of PSII (Fv/Fm), which gives the information about the proportion of the light absorbed by chlorophyll in PSII that is used in photochemical processes that it decreased under stress conditions. The aim of this greenhouse study was investigating some stomatal and non- stomatal limiting factors in photosynthesis rate and biomass of Kochia under drought stress conditions.
To comparison the photosynthetic parameters of kochia under drought stress, a pot experiment was carried out in completely randomized design with three replications in University of Ferdowsi in 2013. There were 9 treatments included control (no drought), light drought stress during the vegetative phase, heavy drought stress during the vegetative phase, light drought stress during the reproductive phase, heavy drought stress during the reproductive phase, light drought stress during the vegetative phase and heavy drought stress during the reproductive phase, heavy drought stress during the vegetative phase and light drought stress during the reproductive phase, light drought stress during total growth period and heavy drought stress during total growth period. Photosynthetic parameters including photosynthesis rate, transpiration, stomatal conductance, Co2 sub stomatal (by IRGA, Model LCA4), PWUE, SPAD (by SPAD, 502, Japan), chlorophyll content (with spectrophotometer model 6305 by Arnon's method), chlorophyll fluorescence components (chlorophyll fluorescence meter model OSL-FL) and biomass were measured. For statistical analysis, analysis of variance (ANOVA) and FLSD test were performed using SAS ver. 9.1 software.
Results showed that chlorophyll a, chlorophyll b and total chlorophyll content and SPAD under drought stress conditions were lower than the control treatment. Effect of drought stress was significant on chlorophyll fluorescence indices so that maximum quantum yield of photosystem II declined significantly due to increasing of initial fluorescence (Fo) and decreasing of maximum fluorescence (Fm). Transpiration, stomatal conductance and co2 sub-stomatal did not differ significantly from control. Photosynthetic rate also decreased in drought stress at different growth stages. The most and lowest of biomass observed in control and heavy drought stress during growth period, respectively.
Conclusions :Finally, this study showed that stomatal parameters (Transpiration, stomatal conductance and CO2 sub-stomatal) shown the same reaction under stress and non- stress conditions. Even under heavy drought stress, this plant is able to hold open stomata and maintain the continuity of CO2 absorption that it refers to the high resistance of Kochia. Therefore stomatal limiting factors didn’t have role in limit photosynthesis. Unlike stomatal limiting factors, non- stomatal factors had a significant positive correlation with photosynthesis rate and a decrease in each of them reduces photosynthesis rate.

In order to investigate the effect of water deficit stress on morphology and photosynthesis pigments contents of Salvia leriifolia Bench., an experiment was conducted in completely randomized design with three replications under greenhouse conditions. Water deficit treatments were Fully irrigated or Control (-0.035 MPa), Mild stress (-0.138 MPa), Moderate stress (-0.516 MPa) and Severe stress (-1.92 MPa). One set of stressed plants were kept constantly in different levels of matric potentials (Water deficit set) and the other (recovery set) irrigated to maximum water holding capacity after soil water was depleted in each stress levels. The results showed that transpiration, yellow leaves weight significantly decreased in mild stress but chlorophyll a, b content increased comparing control. There was no significant difference between constant and recovery stressed treatments to -0.516 MPa in all traits. Results indicated that leaf number, leaf area and also shoot and root dry weight were significantly (P≤ 0.05) decreased with increasing matric potential beyond -0.516 MPa. The highest SLA (135 cm2.g-1) was obtained in -0.138 MPa and it had only significant difference (P≤ 0.05) with severe water deficit treatments. Results also showed that Root to Shoot ratio increased by 3.9- 4.3 times comparing control. Despite the chlorophyll content decreased in matric potential -1.92 MPa, but total carotenoids concentration and also the ratio of carotenoids to total chlorophyll were significantly increased compared to controls.

According to limited availability of water for crops production, fining genotypes with optimal efficiency of water use is among the research priorities. For this purpose this research was conducted in order to investigate the effect of water deficiency tension on photosynthesis indices and finally production and forage yield of three sorghum genotypes as factorial in a completely randomized design in University of Mohaghegh Ardabili research greenhouse in 2013. The experiment treatments consisted of water deficiency tension at four levels (80, 65, 45 and 25% of field capacity) and three genotypes of sorghum (KFS17, KFS6 and KFS2). The results showed that the main effect of water deficit tension and genotype had significant difference in most measured traits at one percentage probability level. Interaction between water deficit tension and sorghum genotype was significant only on the amount of chlorophyll a, carotenoids, chlorophyll stability and forage yield. So that the deficit water tension caused decreasing of chlorophyll a, b, total chlorophyll, maximal fluorescence (Fm), quantum yield of photo system II (Fv/Fm) and forage yield and caused increasing in chlorophyll a to b ratio, carotenoids, chlorophyll stability, Fo (minimal fluorescence in dark adapted conditions), Ft (fluorescence intensity or instantaneous). Although KFS6 genotype had the highest value in many of the measured traits, however, the highest yield was belonged to KFS2 genotype and then KFS17. Also based on regression analysis the KFS17 genotype showed the highest correlation between chlorophyll a, total chlorophyll and carotenoid amounts with the yield. Generally, yield reduction in KFS2 genotype can be related to consume more plant photosynthesis materials in order to withstand against the tension.

Among the environmental stresses, salinity is a major limiting factor in world legumes production is considered. In this study, sodium chloride and Salicylic acid interaction on growth parameters were investigated in greenhouse with factorial arrangement in randomized complete block design with three replications. The plant consisted of three cultivars of lentil (Kimiya, Kermanshah and Gachsaran), exposed to different concentrations of sodium chloride (0, 60 and 120 mM NaCl) and solution sprayed by salicylic acid (0, 0.2 and 0.5 mM) were used. In plants only exposed to sodium chloride, with the increase of sodium chloride concentration, chlorophylls, carotenoids and relative water content decreased compared to control while, amount of soluble sugar, electrolyte leakage, MDA, proline and amount of sodium and chloride accumulation increased. In plants exposed to sodium chloride and Salicylic acid, compared with those were only exposed to salinity, in the same concentration of sodium chloride photosynthetic pigments and relative water content were higher, and amount of soluble sugar, electrolyte leakage, MDA, proline and amount of Na accumulation decreased compared to plants only exposed to sodium chloride. The result showed that spray of Salicylic acid (as an antioxidant) caused resistance against salt stress and decreased side effects of sodium chloride in Lens culinaris Medik. Kimia variety in foliar application with 0.2 mM salicylic acid and high NaCl levels had the highest relative water content, proline, soluble sugars, chlorophyll and carotenoid.

Cadmium is a toxic element which due to its great cumulative potential in plant organs causes important morphological and physiological changes in plant structure. In order to study of effect of salicylic acid priming on reduction of chloride cadmium damage on maize seedlings, a factorial experimental based on completely randomized design with three replications was conducted at the research laboratory of University of Damghan during 2012. The experiment consisted of two factors including a salicylic acid application (application and no application) and different CdCl2 concentrations (0, 0.05, 0.1 and 0.2 mM). The results showed that increase of CdCl2 concentration resulted in reductions in photosynthesis pigments, anthocyanin and morphological characteristics of maize seedlings. However, MDA, proline and phenolic compounds of maize seedlings were increased as CdCl2 concentration increased. Priming with salicylic acid increased photosynthesis pigments, anthocyanin, phenolic compounds, proline and morphological characteristics and decreased MDA in maize seedlings compared with the control (no application of salicylic acid). Salicylic acid application at the highest concentration of CdCl2 (0.2 mM) increased chlorophyll b, carotenoid, phenolic compounds of shoot and root as 8.24, 19.64, 29.13 and 47.05%, respectively, compared to the control. This reduced the MDA of shoot and root as 27.04 and 16.19%, respectively.

In order to study the effects of water stress and different amounts of sulfur fertilizer on grain yield, nutrient status and chlorophyll content in black cumin (Nigella sativa L.) a field experiment as split plot design with three replications was conducted at Ghaen city in 2009. Treatments included three levels of irrigation after 50, 100 and 150 mm evaporation from Class A pan as main plot and four levels of sulfur fertilizer including 0, 75, 150 and 225 kg/ha from bentonite-sulfur source as sub-plot. Statistical analysis of the results showed that water stress has significant effect on grain yield and essential oil of black cumin. At the level of 150 mm evaporation from Class A pan, the grain yield decreased by 22.8% and essential oil by 27.6%. Application of 225 kg/ha sulfur fertilizer increased grain yield up to 7.2%. Water stress and sulfur fertilizer treatments had only significant effect on chlorophyll a content. However, water stress decreased chlorophyll a content, but sulfur fertilizer application up to 225 kg/ha increased the content of chlorophyll a. In this study, water stress decreased potassium content in black cumin leaves, but increased the sodium and calcium accumulation. Although application of sulfur fertilizer affected significantly the potassium and magnesium contents in shoots, but did not have significant effect on sodium and calcium contents.