جستجوی مقالات مرتبط با کلیدواژه « هدایت روزنه ای » در نشریات گروه « آب و خاک »

In recent years, due to lack of water, using wastewater including fish effluents, for agricultural purposes has increased. Depending on water quality, irrigation method and type of crop might change. The elements present in the fish effluent interact with each other and it is possible to increase or decrease the absorption of an element through the leaves to have a negative effect on the yield and growth indicators. Therefore, the aim of this research is to provide solutions for the use of rainbow trout wastewater in the sprinkler irrigation system to provide irrigation water for potato cultivation and the effect of leaf washing with appropriate quality on yield, tuber dry matter percentage, diameter and height of stem, tuber specific weight, chlorophyll, photosynthesis, transpiration and stomatal conductance.This experiment was conducted in research farm No. 2 of Kurdistan University ,Dehgolan plain in Kurdistan province in the form of a factorial experimental format based on a completely randomized design with three replications in the summer of 2019, 2020 and 2021. The investigated factors include irrigation at two levels, A1 (irrigation with well water) and A2 (irrigation with fish farm effluent), as well as washing the leaves of the plant in four levels, B1 (Before applying fish farm effluent to the leaves, they were washed for ten minutes with fresh water), B2 (after applying fish farm effluent to the leaves, they were washed for ten minutes with fresh water), B3 (The leaves were washed with fresh water for ten minutes both before and after applying the fish farm effluent to them) , B4 (the leaves were not washed at all).Sprinkler irrigation system with micro sprinkler was used to irrigate. At the end of the growing season, the tuber yield values of different treatments were measured. Chlorophyll meter (SPAD-502-Minolta-Japan) was used in order to measure chlorophyll of leaf. The indicators related to gas exchange including photosynthesis, stomatal conductance and transpiration were measured by a portable device (ADC BioScientific LCi Analyzer Serial No. 32648). Data were analyzed with Rstudio, and mean values of the treatments were compared by the least significant difference (LSD) test at 5% and 1% significance level.The results showed that washing the leaves with fresh water significantly affected on the yield and other growth indicators. The highest amount of yield, stem diameter, specific gravity of potato, chlorophyll meter reading, photosynthesis, transpiration and stomatal conductance were 550.8 grams per pot, 9.941 mm, 1.113 g cc-1, 53.59, 22.00 (μmol m-2 s-1), 7.028 (mmol m-2 s-1), 0.4439 (mmol m-2 s-1), respectively. These amounts were results of applying B3 treatment. Also, the highest percentage of potato tuber dry matter was 13.3% and the highest figure for stem height was 35.46 cm, which were the result of applying B4 treatment.The results of this research show that compared to well water, fish effluent increased yield of potato by 16.4%, stem diameter by 4.67%, stem height by 3.72%, chlorophyll meter reading by 9.67%, and stomatal conductance by 15.40%. Also, the results showed that treatment B3 compared to B4, increased yield 64.78%, stem diameter 39.55%, tuber specific weight 48.54%, chlorophyll meter reading 41.21%, photosynthesis by 4.40%, transpiration by 25.86% and stomatal conductance by 10.13%. It is suggested to use the strategy of simultaneous use of fish effluent and fresh water in the sprinkler irrigation system to increase yield and growth indicators.

A greenhouse study was conducted to investigate the effect of biochar on vegetative and reproductive stages of maize (Zea mays L.) under water deficit stress. A biochar produced from the pyrolysis of grapevine wood chips (at 350℃), was mixed with a sandy loam soil (from Alborz province) at the rates of 0, 0.5, 1, 2, 3, 4 and 5 % w/w, which were used for planting maize. The experiment consisted of two deficit irrigation treatments in vegetative (I1) and reproductive (I2) stages and one sufficient daily irrigation treatment throughout the growing season (I3). Plants in the period of deficit irrigation were subjected to successive wetting (via watering up to FC) and drying (via plant transpiration) soil cycles with water content varying between 0.30 and 0.18 cm3cm-3, respectively. Some plant physiological characteristics including transpiration rate, stomatal conductance and photosynthesis rate were determined during the drying cycles and biomass at the end of experiment. Soil water retention curve and unsaturated hydraulic conductivity (Kh) were measured by a combination of the Sandbox, Pressure plate, and Hyprop apparatus. The results showed that the addition of four percent biochar to the soil increased transpiration rate by 81, 100 and 49% in I1 and 228, 198 and 61% in I2 at soil water contents of 0.18, 0.20 and 0.23 cm3 cm-3, respectively. The effect of biochar on improving the physiological parameters of plants under drought stress in the reproductive stage was greater than the ones in the vegetative stage. Due to this improvement, the harvest index of plants in soils containing biochar increased by 35 and 50% in I1 and I2, respectively. Under the biochar impacts, grain water use efficiency also increased by 42% and 49% in I1 and I2, respectively. Given the small effect of biochar on increasing soil water retention especially in the dry range, it seems that the performance of biochar to keep higher Kh and matric flux potential were the most important factors to improve transpiration rate in the soil drying cycles.

In order to study the effect of foliar application of nano and conventional zinc oxide and silica fertilizers on yield and yield components of millet Pishhang cultivar, an experiment was conducted in 2017 in the research farm of Birjand branch, Islamic Azad University, Birjand as split plots based on a randomized complete block design with three replications. Two levels of irrigation (irrigation based on 50% and 100% of water requirement by FAO method) were as the main plots. Also seven treatment of fertilizer foliar application (no foliar application (control), zinc oxide, silica oxide, nano zinc oxide, nano Silica, zinc oxide + silica and nano-zinc + nano-silica) were as the sub-plots. The results showed that deficit irrigation reduced plant height (36.2%), panicle length (21.2%), stomata conductance (14.2%), number of panicles per square meter (39.6%), number of seeds per panicle (33%), grain yield (62.8%), biological yield (38.4%) and harvest index (45.7%) compared to the control (100% water requirement). The effect of fertilizer foliar application was significant on chlorophyll index, stomata conductance, number of panicles per square meter, grain yield and biological yield. The highest grain yield was obtained from the application of common zinc oxide, nano-silica and zinc oxide+silica, which increased by 27.7, 26.8 and 15.9%, respectively, compared to the control. Also, the highest biological yield was obtained from the application of zinc + silica, ordinary zinc and nano-silica, which had an increase of 16.3%, 8.8% and 6.6%, respectively, compared to the control. Based on the results of this experiment, in order to preserve the environment and achieve maximum grain yield of millet in Birjand region, optimal irrigation and foliar application of nano-silica can be used.

Stomatal conductance is one of the important indices to assess water deficit stress in plants. To evaluate stomatal conductance in corn leaves for scheduling irrigation, an experiment was conducted at East Azarbaijan Research Center for Agriculture and Natural Resources. The experiments were as Randomly Complete Blocks with three replications and with treatments of a: full irrigation, b: deficit irrigation from stages of 6-7 leaves to the end of ripening with full irrigation at flowering stage, c: deficit irrigation from stages of 6-7 leaves to the end of ripening with full irrigation at dough stage. The stomatal dimensions were determined by copy method. Stomatal conductance was measured along a leaf with different distances, at different leaves of a plant and at before and after irrigation events by a porometer. Results showed that the stomatal along a leaf and at leaves of a plant had a variable value. So that the stomatal conductance increased with increasing distance from petiole to leaf tip and with an increasing leaves number for soil surface to the canopy. The stomatal conductance changes along the leaf and its variability in leaves numbers were modeled as Logistic functions. The temperature variability along leaf was modeled as Sinusoidal function. Results also showed that the stomatal conductance from irrigation treatments were different. The stomatal conductance from two days after irrigation were similar and averaged 0.31 ms-1. The suitable time for irrigation and its cutoff were at stomatal conductance of 0.21 and 0.33 ms-1.

Peppermint is one of the medicinal and aromatic herbs that has many medicinal, nutritional, cosmetic and hygienic uses. One of its prominent properties is its antimicrobial properties. In order to evaluate the effect of organic fertilizer and different levels of irrigation on the growth stages of peppermint, a greenhouse experiment was conducted in a greenhouse research environment in Ferdowsi University of Mashhad in spring 1977 in a two-factorial completely randomized design with 3 replications. Peppermint pepper was done. Experimental treatments included irrigation treatments at 4 levels (50, 75, 100 and 120% of plant water requirement) and 4 levels of organic fertilizer (cow manure at 2 levels (5 and 10 t ha-1) and poultry manure at 2 levels (20 and 70 G / l) that were used at different stages of pepper plant growth. The results showed that the interaction of irrigation and fertilizer levels on morphological characteristics of peppermint such as plant height and stem diameter were not significant on leaf fresh weight, root fresh weight and root dry weight (at 0.01 level). It was very meaningful. It can be concluded that the highest amount of irrigation and cow and poultry manure increased leaf fresh weight and organic fertilizer had no effect on fresh and dry root weight. Interaction of irrigation and fertilizer levels on physiological characteristics of peppermint such as stomatal conductance, leaf relative water content and electrolyte leakage were not significant and were highly significant at chlorophyll a, chlorophyll b and total chlorophyll at 0.01 level. The lowest irrigation and the highest amount of poultry manure increased chlorophyll a and the lowest irrigation and the lowest amount of organic fertilizer increased chlorophyll b and total chlorophyll and was significant at 0.05 level of leaf chlorophyll index (chlorophyll spd index). The lowest amount of irrigation and the highest amount of organic fertilizer increased leaf chlorophyll index. It can be concluded that peppermint was more sensitive to different levels of irrigation and fertilizer levels did not have a positive effect on peppermint yield and among organic fertilizers the effect of poultry manure was more than cow manure.

Considering the great value of water, irrigation scheduling, and cultivation of medicinal plants, this research was conducted at the Faculty of Agriculture, Lorestan University, with the aim of scheduling irrigation of summer savory using CWSI and applying different levels of water stress under the condition of pot planting. In this research, seeds of summer savory were cultivated  with three replications under four irrigation treatments of 100%, 80%, 60%, and 40% of readily available water (RAW) (IR100, IR80, IR60 and IR40). Irrigation of the control treatment (IR100) was carried out when all the soil RAW was depleted. Irrigation of the other three treatments was carried out at the same time but with, respectively, 80%, 60%, and 40 percent of the volume applied to IR100.  The canopy cover temperature in IR100 and air temperature (dry and wet) were measured on the day after (8-14 o’clock) and before irrigation (12-15 o’clock) in order to construct the lower and upper limits base lines required to calculate CWSI. According to the result, the upper base line equation is (𝑇𝑐-𝑇𝑎) UL = 0.69, and the lower base line is (𝑇𝑐-𝑇𝑎) LL = 0.2787 - 0.1134 (VPD). Result showed that the effect of water stress on yield was significant. The highest yield was observed in IR100 (1.756 g / plant) and the lowest yield was observed in IR40 (1.421 g / plant). The crop water stress index (CWSI) of the four treatments in the day before irrigation was 0.19, 0.21, 0.28, and 0.46, respectively. According to this information, the permissible CWSI index for irrigation scheduling of summer savory growing in pots was 0.19. The result of means comparison indicated that differences between IR100 and IR80 in values of CWSI and canopy cover temperature were not significant, but they were significant between IR100, IR60 and IR40.  The increment of CWSI in IR80, IR60 and IR40 were 10%, 47%, and 142 percent relative to the IR100. In this research, a strong correlation (r= -0.978*) was obtained between CWSI and stomatal conductance.

According to the amount of wheat production in Fars Province and occurrence of drought, application of crop’s residual on agricultural land in form of biochar may improve soil fertility and increase crops yield. Therefore, the current research was conducted to study the effect of different levels of wheat straw biochar and deficit irrigation on wheat growth and yield. The treatments included four levels of biochar (0, 1.25, 2.5 and 3.75 % w/w) and three levels of irrigation (100, 75 and 50 % crop water requirement). Under full irrigation treatment, increasing in biochar to 1.25%w/w was increased crop height by 11.5% in comparison with that obtained in no biochar application. Biochar levels of 1.25, 2.5 and 3.75% w/w increased (decreased) stomatal conductance (green canopy temperature) by 26.8, 31.2 and 37.9% (15.2, 21.4 and 23.4%), respectively, in comparison with that obtained in no biochar application, under full irrigation treatment. Also, the maximum number of tillers per wheat plant (3.7), number of seed per tillers (36.1), 1000 seeds weight (54.1 g) and above ground dry matter (65 g) were observed in 1.25 % w/w biochar treatment, and further increase in biochar declined these parameters in comparison with control as the soil become more saline. It can be concluded that deficit irrigation of 75% crop water requirement and application of 1.25% w/w biochar is recommended due to positive effect of these treatments on yield and yield components.

Drought is one of the most important factors limiting crop growth and in most phases of plant growth effect is harmful and destructive. Therefore use of practice to reduce its adverse effect is very important. It seems that, through exogenous application of glycine betaine, plant resistance to drought stress can be increased. In order to investigate the effect of drought stress and glycine betaine foliar spraying on photosynthetic parameters of chickpea, a factorial experiment was conducted in a completely randomized block design with three replications in a research greenhouse of the Faculty of Agriculture of Lorestan University in 2017. Drought stress in four levels (control, 75, 50 and 25 of field capacity) and foliar spraying application of glycine betaine in three levels (0, 25 and 50 mM) were applied. The results showed that drought stress significant at 1% level of probability decreased photosynthesis rate, transpiration rate, stomatal conductance, intercellular CO2 concentration, photosynthetic water use efficiency and carboxylation efficiency, but glycine betaine notably improved them. Glycine betaine application enhanced the photosynthesis in water-deficit experiencing plants, mostly due to a greater stomatal conductance and carboxylation efficiency of CO2 assimilation. It could be concluded that spraying glycine betaine (25 mM) improve photosynthetic parameters in drought conditions and induces more water stress tolerance in chickpea.

The range of soil water content where plant growth is least limited by water potential, soil aeration or mechanical resistance is called least limiting water range (LLWR). This study evaluated the values of LLWR determined according to the procedures proposed by da Silva et al. with those calculated on the basis of sunflower plant (Helianthus annuus L) response (LLWRP). In both methods LLWR is taken as the difference between the two soil moisture limits designated as upper (θUL) and lower (θLL). In the first method, the two limits are determined basically from the soil moisture and soil resistance characteristic curves, almost overlooking the plant type and its particular needs or behaviors. In the second method, as proposed in this research, the two limits are determined based on the stomatal response in a sandy clay loam soil packed into PVC tubes (called pots hereafter) with 30 cm diameter and 70 cm height at three compaction levels (soil bulk density equal to 1.75, 1.55 and 1.35 Mg.m-3) designated as D1, D2 and D3. Each pot was planted with three pre-soaked sunflower seeds and pots were kept under optimum condition until onset of the flowering stage. At this time two successive drying cycles were imposed and soil moisture and midday stomatal conductance were routinely measured. LLWRP were computed on the basis of relationship between soil matric suction and stomatal conductance. Results showed that on the basis of stomatal conductance behavior water uptake began at the soil matric suctions of 44, 16, 60 and continued up to 17394,31614, 39983 cm in D1, D2 and D3 treatments, respectively. Appreciable differences were observed between LLWR and LLWRP particularly when the lower limit moisture suction (equivalent to θUL for LLWR) was set at 330 cm (LLWR330). LLWR330 values of 0.148, 0.147 and 0.080 cm3cm-3 were obtained for D1, D2, D3 treatments, respectively, which were 51, 49 and 63 percent lower than the corresponding LLWRP values. This differences imply that the two moisture limits (θUL and θLL) proposed by da Silva et al. may not be applied indiscriminately for all plants and thus need to be modified according to plant needs or responses.

Drought and its resulting stress is one of the most important common environmental stresses that limit agricultural productions. In order to evaluate the effect of cattle manure biochar on the growth, yield, and water use efficiency of spinach at different soil moisture status, a factorial completely randomized design with 3 replications was conducted under greenhouse conditions during October 2014 to January 2015. Treatments consisted of four biochar levels (0, 1.25, 2.5 and 5% wt of initial soil) and three soil moisture levels (FC (without stress), 0.7FC, and 0.55FC). To compensate the water losses via evapotranspiration, the pots were weighted every day and water stress was imposed by adding the water required in each treatment. Total water consumption during the growing season was also determined. Results indicated that application of both soil water stress levels resulted in significant reduction in leaf area, stomatal conductance, water consumption, and fresh and dry weight as compared to those of the controls (without water stress and biochar application). The greenness index significantly increased by 14%, 14%, and 11 % as compared to that of the control when soil moisture level of 0.55 FC was applied at the first, second, and third growth stages (40, 55 and 70 days after planting), respectively. Application of biochar also significantly increased greenness index, leaf area, and stomatal conductance as compared to that of the control. Soil moisture stress up to 0.7FC decreased the plant water consumption; however, it did not affect the water use efficiency, significantly; while water stress level of 0.55 FC decreased water use efficiency significantly. In general, application of 1.25 biochar (25 ton/ha) as compared to the control decreased the negative effects of water stress on plant (reducing leaf area, fresh and dry weight, etc.) and improved plant growth indices and increased the growth of plant at all of the applied water stress levels. Therefore, in order to reduce water consumption and improve the growth and yield of plants, biochar application, especially under drought stress conditions or in greenhouse conditions, is recommended. Meanwhile, performing such an experiment under field conditions is also suggested.

Water shortage is the most important factor affecting crop production in the world. The deficit irrigation is a way to reduce water consumption in farming. The Partial Root- zone Drying (PRD) irrigation is a new improvement in deficit irrigation in which the half of the root zone is irrigated alternatively in scheduled irrigation events. In the fixed partial root zone drying (FPRD) the irrigation is fixed to one side of the root zone in the growing season. Maize is a drought sensitive crop. In maize, secondary traits related to drought resistance are considered in producing tolerate cultivars.
An experiment was conducted in order to investigate the effects of regulated deficit irrigation, variable partial root zone drying (PRD) and fixed partial root zone drying (FPRD) on the yield, physiological and photosynthetic parameters of forage maize (KSC 704) during the growing seasons of 2014 in Mashhad region. A factorial experiment based on randomized complete block design with four replications was carried out. The treatments included the full irrigation (FI) and the deficit irrigations (regulated deficit irrigation (DI) and the replacements of 80 % (DI80) and 60 % (DI60) of total water requirement, fixed PRD (FPRD) at 100% (FPRD100), 80% (FPRD80) and 60%(FPRD60) of water requirement, and variable PRD at 100% (PRD100), 80% (PRD80) and 60% (PRD60) of water requirement). Drip irrigation tapes were placed between plant rows. In the full irrigation and regulated deficit irrigation treatments, the plants were irrigated from two sides for every irrigation. In the PRD, one of two neighboring tapes was alternatively used for irrigation. In FPRD, a drip tape was used for two plant rows and irrigation was fixed to one side of the root. The irrigation interval was 3 days for all treatments. Dry and fresh forage yield, leaf area index (LAI), stomatal conductance, leaf relative water content (RWC) and chlorophyll content were measured.
All the measured traits were affected by the deficit irrigation. The highest fresh forage yield (72099 kg/ha) was produced by the full irrigation treatment. The statistical comparison showed that there was no significant difference between regulated deficit irrigation and PRD method for the fresh forage yield. But the FPRD treatment reduced the fresh forage yield. There was no significant difference between the fresh forage yield of FI and PRD80 treatments. The dry forage yield was affected by the different irrigation methods, irrigation levels and the interaction effects of the treatments All the measured traits were affected by the deficit irrigation. The highest fresh forage yield (72099 kg/ha) was produced by the full irrigation treatment. The statistical comparison showed that there was no significant difference between regulated deficit irrigation and PRD method for the fresh forage yield. But the FPRD treatment reduced the fresh forage yield. There was no significant difference between the fresh forage yield of FI and PRD80 treatments. The dry forage yield was affected by the different irrigation methods, irrigation levels and the interaction effects of the treatments (p According to the results, it seems that the negative effects of water stress on physiological and photosynthetic parameters in the early growing season is not significant and increases with the aging of the plants. Water stress decreases the absorption of carbon dioxide and the photosynthesis by reduction in the stomatal conductance. As well as, reducing the leaf area decreased photosynthetic area and the production of asymylats in the water stress conditions and ultimately reduced the forage yield significantly. The PRD method increased irrigation water productivity. With respect to this fact that no difference between the dry matter yield, LAI, chlorophyll content and RWC in the FI, PRD100 and PRD80 treatments was observed, it seems that applying Partial Root- zone Drying (PRD) method will result in lower water consumption during forage maize production at Mashhad environmental conditions.

In this research, in order to study the effect of deficit irrigation on the physiological indexes of maize (single cross 704), an experiment in randomized complete block design with three replicate, was performed in the experimental field of Shahid Chamran university during the year 2013.The Irrigation treatments included 100, 75 and 50 percent of the maize water requirement that was calculated through the evapotranspiration of the reference plant (grass). Volumetric lysimeter were used for the cultivation and the depth of the groundwater table was held at 70 centimeters from the soil surface. A lysimeter with complete irrigation and without the presence of water table was used as control treatment. The amount of the physiological indexes was measured 60,74 and 88 days after sowing for Determination of Stomatal conductance, photosynthesis speed and chlorophyll's density. The results showed that with increasing of water stress, the amount of the physiological indexes decreased. The maximum and minimum amount of chlorophyll's density was 55.38 and 39.66, obtained from the treatments with 100 and 50 percent of maize water requirement irrigation, respectively. The maximum and minimum amount of Stomatal conductance and photosynthesis speed obtained from treatments with 100 and 50 percent of maize water requirement irrigation, respectively. The alteration process of these three indexes during the infancy showed that from the eighth week after the cultivation till the end of the maize infancy the maize petal loophole conduction, photosynthesis velocity and the chlorophyll's density will decrease. also, the results showed that the maximum maize biomass was 4.63 ton/ha obtained from the treatment with 100 percent of maize water requirement irrigation and the minimum maize biomass was 3.72 ton/ha obtained from the treatment with 50 percent of maize water requirement irrigation.

Water, oxygen, temperature, and mechanical resistance are the soil physical factors that can directly influence plant growth. Under favorable temperature not only sufficient water is available for the plant at the last limiting water range (LLWR), but also the other two factors are not limiting for the root activity. In order to study the corn single cross (Zea mays L. (response to the soil water content with reference to LLWR, a greenhouse experiment was conducted. Topsoil with clay loam texture was passed through 4.76-mm sieve, and transferred into PVC cylinders (diameter 15.2 cm and height 50 cm). The soil columns were compacted to achieve two levels of bulk densities (1.25 and 1.6 g cm-3). With three soil moisture levels (the LLWR range, less than its lower limit and greater than its upper limit), two compactions and three replications, 18 soil columns were prepared. Three corn seeds were planted in each column. After seedling emergence and thinning them to one plant per PVC pot, soil water treatments were applied at 5-leaves growth stage. Plant traits including plant height, leaf area, leaf relative water content and stomatal conductance were measured. The difference in these traits between the three soil water levels were significant (p<0.01). Increase in bulk density decreased LLWR (v/v) from 18% at 1.25 g cm-3 to 6% at 1.6 g cm-3. Mean values comparisons of the plant traits at both bulk densities showed that the soil water range defined by LLWR led to the highest values of the traits. Therefore, the thresholds values corresponding to air-filled porosity of 10%, permanent wilting point of 1.5 MPa suction and mechanical resistance of 2 MPa (as defined in the LLWR concept) were verified for the corn growth in the examined soil.

In order to study the sensitivity of vegetative growth to water deficit stress of a late-maturing peach (Prunus persica L. cv. Elberta) under orchard conditions, an experiment was conducted as randomized complete-block design with three treatments and four repetitions in Shahdiran commercial orchard in Mashhad during 2011. Three irrigation treatments including 360 (low stress), 180 (moderate stress) and 90 (severe stress) m3ha-1week-1 using a drip irrigation system (minimum stem water potential near harvest: -1.2, -1.5 and -1.7 MPa, respectively) from the mid-pit hardening stage (12th of June) until harvest (23rd of Sep.) applied. Predawn, stem and leaf water potentials, leaf photosynthesis, transpiration, stomatal conductance and leaf temperature, the number of new shoots on fruit bearing shoots and vegetative shoots lengths during growing season as well as leaf area at harvest were measured. The results showed that water deficit stress had negative effects on peach tree water status, thereby resulting in decreased leaf gas exchange and tree vegetative growth. As significant decreased assimilate production of tree was resulted from both decreased leaf assimilation rate (until about 23 % and 50 %, respectively under moderate and severe stress conditions compared to low stress conditions) and decreased leaf area of tree (until about 57% and 79%, respectively under moderate and severe stress conditions compared to low stress conditions at harvest). The significant positive correlation between leaf water potential and vegetative growth of peach revealed that shoot growth would decrease by 30% and 50% of maximum at leaf water potential of –1.56 and –2.30 MPa, respectively.

Continuous availability of soil water is an important factor for plant growth. Both lack of adequate access to water in soils, or adequate oxygen in saturated soils, may reduce or even stop plant growth. To study the behavior of pistachio seedling at various moisture levels and to determine non-limiting water range for its growth, a greenhouse experiment with a completely randomized design was conducted at two levels of bulk density (BD) i.e. 1.5 and 1.8 g cm-3, six moisture levels for BD 1.5 g cm-3 (33-43%, 25-33%, 19-25%, 14-19%, 11-14%, and 7-11% on volume basis) and BD level of 1.8 g cm-3 (27-33%, 23-27%, 19-23%, 15-19%, 13-15%, and 8-13% v/v), with three replications. After transferring the pistachio cv. Sarakhsi seedlings (Pistachio vera L.) into soil cylinders and their establishment, six different volumetric water contents for each BD level were applied. Stomatal conductance of the third mature leaf, proline content, leaf relative water content (RWC) and leaf area were determined. The effect of moisture levels on all growth parameters were significant (P<0.01). With bulk density of 1.5 g cm-3, the seedlings experienced vegetative and physiological limitations in the range of 7 to 14 percent volumetric water content, thus, non-limiting water range for pistachio seedling at this BD level ranged from 14 to 43 percent v/v. In the compacted treatment (BD of 1.8 g cm-3), the vegetative growth and physiological activities suffered limitations within the range of 8-19 percent water content due to moisture deficit, and, in the range of 23-32, were retarded due to soil poor aeration. Also, non-limiting water range at this BD ranged from 19-23 percent water content. The least limiting water range predicted from Dasilva et al. model at the two BD of 1.5 and 1.8 g cm-3 were 11- 25% and 20- 22 percent, respectively. The differences between the predicted range and the range obtained based on the seedling response implies the need for the calibration of the predicting model for each particular soil and plant.

Continuous availability of soil water is an important factor for plant growth. Both lack of adequate access to water in soils and adequate oxygen in saturated soils، may reduce or even stop plant growth. In order to study the behavior of pistachio seedling (Pistachio vera L.) at various moisture levels and to determine non limiting water range for its growth، a greenhouse experiment with two levels of compaction at six moisture levels with three replications was conducted. The air dried soil was passed through soil 4. 75 mm sieve، and transferred into 36 PVC cylinders (diameter 15. 24 and height 50 cm)، the soils of cylinders were compacted in order to prepare two levels of soil bulk density (1. 35 and 1. 65 g cm-3). After transferring the pistachio seedlings into soil cylinders and their establishment، six different volumetric water contents، from saturation to permanent wilting point، for each compaction level were applied. Stomatal conductance in the third mature leaf was measured in the course of exerting moisture treatments between 1:0 to 2:0 pm، during the experiment. Number of leaves and height of seedlings were recorded and leaf relative water content (RWC) and proline content were determined. The effect of moisture levels on all growth parameters were significant (p≤0. 01). With bulk density of 1. 35 g cm-3، the seedlings faced with vegetative and physiological limitations at the range of 7 to 14 percent volumetric water content. Thus non-limiting water range for pistachio seedling at this bulk density level ranged from 14 to 49 percent volumetric moisture. In the compacted treatment (bulk density of 1. 65 g cm-3) both vegetative growth and physiological activities were considered within the range of 9-22 percent water content due to moisture deficit and at the range of 33-38، because of soil poor aeration led to growth retardation. Also non-limiting water range at this compaction level ranged from 22-33 percent water content. The least limiting water range predicted from Dasilva et al. model at the two Db of 1. 35 and 1. 65 g cm-3 were 10- 24. 5 and 17- 28 percent، respectively. The differences between the predicted range and the range obtained based on the seedling response implies the need for the calibration of the predicting model for each particular soil and plant.

Drought and low rainfall are arising problems in recent years in many countries that limit agricultural production. An appropriate solution to overcome water deficit stress in sustainable agriculture is establishment of mycorrhizal symbiosis in plants. Mycorrhizal fungi affect plant growth by widespread activity in roots and soil. A greenhouse experiment was carried out using tomato (Lycopersicon esculentum L. cv. Behta) plants inoculated with two species of mycorrhizal fungi Glomus intraradices (Gi) and Glomus etunicatum (Ge) in a sterile soil. The experiment was factorial based on a completely randomized design with three replications. After plants establishment, three ranges of soil moisture: (0.9FC–FC) [D0] and (0.7FC-0.8FC) [D1] and (0.55FC-0.65FC) [D2] were applied to the pots. In both fungal species root mycorrhizal colonization decreased by decreasing soil moisture. Inoculation of plants with Gi and Ge increased shoot dry weight by 14.5% and 16.2%, respectively, compared to non-mycorrhizal plants but shoot dry weight declined by decreasing soil moisture. Mycorrhizal fungi significantly (P<0.01) increased leaf relative water content (RWC), leaf water potential (LWP) and stomatal conductance (gs) but these parameters were decreased by decreasing soil moisture. Mycorrhizal plants at all levels of soil moisture had more shoot P concentration than the control plants, but Ge significantly increased shoot K concentration. Thus, both P and K contents decreased by decreasing soil moisture. Based on the results, it can be concluded that the arbuscular mycorrhizal fungi can increase tomato growth and nutrient uptake under water deficit stress.

In order to study the physiological responses of two barley cultivars to salinity stress, a 4-replicate CRD greenhouse experiment was conducted during at the College of Agriculture, Shiraz University, Iran2003-2004. The treatments consisted of two barley cultivars: Afzal and Reyhan and five salinity levels: 0, 4, 8, 12 and 14 dS/m. Seedling emergence, number of tillers and leaves per plant, leaf area and dry matter decreased with increasing salinity levels. The reductions were lower in Afzal (salt tolerant) than Reyhan (salt sensitive). A lower Na+ and higher K+Na+ in Afzal compared to Reyhan were observed under high level of salinity. The results of the present experiment also showed that the tolerance to salinity was associated with a greater stomatal conductivity, as well as transpiration and photosynthesis rate. Sub-stomatal CO2 concentration in both cultivars decreased with an increase in salinity, with the exception of 12dS/m, where it led to an increase in sub-stomatal CO2 concentration. Leaf temperature increased with an increase in salinity level in both cultivars, whereas a more pronounced decrease for number of fertile tillers, ears per plant, kernels per ear, thousand grain weight and harvest index was observed in Reyhan compared to Afzal .Since a higher tolerance to salinity in Afzal was apparently associated with a lower concentration of Na+ and a higher K+/Na+ ratio of the shoots, this trait could probably be used for yield improvement of barley cultivars under saline conditions.