Moderate Water Stress Treatment Research Articles

Effects of Vine Water Status on Malate Metabolism and γ-Aminobutyric Acid (GABA) Pathway-Related Amino Acids in Marselan (Vitis vinifera L.) Grape Berries.

Malic acid is the predominant organic acid in grape berries, and its content is affected by abiotic factors such as temperature (fruit zone microclimate) and water (vine water status). The objectives of this study were to explore the potential mechanisms behind the effects of vine water status on the biosynthesis and degradation of berry malic acid and the potential downstream effects on berry metabolism. This study was conducted over two growing seasons in 2021 and 2022, comprising three watering regimes: no water stress (CK), light water stress (LWS), and moderate water stress (MWS). Compared to CK, a significantly higher level of malic acid was found in berries from the MWS treatment when the berry was still hard and green (E-L 33) in both years. However, water stress reduced the malic acid content at the ripe berry harvest (E-L 38) stage. The activities of NAD-malate dehydrogenase (NAD-MDH) and pyruvate kinase (PK) were enhanced by water stress. Except for the E-L 33 stage, the activity of phosphoenolpyruvate carboxylase (PEPC) was reduced by water stress. The highest phosphoenolpyruvate carboxykinase (PEPCK) activity was observed at the berry veraison (E-L 35) stage and coincided with the onset of a decrease in the malate content. Meanwhile, the expression of VvPEPCK was consistent with its enzyme activity. This study showed that water stress changed the content of some free amino acids (GABA, proline, leucine, aspartate, and glutamate), two of which (glutamate and GABA) are primary metabolites of the GABA pathway.

Effects of water stress on starch synthesis and accumulation of two rice cultivars at different growth stages.

Rice is a water intensive crop and soil water conditions affect rice yield and quality. However, there is limited research on the starch synthesis and accumulation of rice under different soil water conditions at different growth stages. Thus, a pot experiment was conducted to explore the effects of IR72 (indica) and Nanjing (NJ) 9108 (japonica) rice cultivars under flood-irrigated treatment (CK, 0 kPa), light water stress treatment (L, -20 ± 5 kPa), moderate water stress treatment (M, -40 ± 5 kPa) and severe water stress treatment (S, -60 ± 5 kPa) on the starch synthesis and accumulation and rice yield at booting stage (T1), flowering stage (T2) and filling stage (T3), respectively. Under LT treatment, the total soluble sugar and sucrose contents of both cultivars decreased while the amylose and total starch contents increased. Starch synthesis-related enzyme activities and their peak activities at mid-late growth stage increased as well. However, applying MT and ST treatments produced the opposite effects. The 1000-grain weight of both cultivars increased under LT treatment while the seed setting rate increased only under LT3 treatment. Compared with CK, water stress at booting stage decreased grain yield. The principal component analysis (PCA) showed that LT3 got the highest comprehensive score while ST1 got lowest for both cultivars. Furthermore, the comprehensive score of both cultivars under the same water stress treatment followed the trend of T3 > T2 > T1, and NJ 9108 had a better drought-resistant ability than IR72. Compared with CK, the grain yield under LT3 increased by 11.59% for IR72 and 16.01% for NJ 9108, respectively. Overall, these results suggested that light water stress at filling stage could be an effective method to enhance starch synthesis-related enzyme activities, promote starch synthesis and accumulation and increase grain yield.

Plant-mediated effects of water-deficit stress on the performance of the jujube lace bug, Monosteira alticarinata Ghauri (Hemiptera: Tingidae) on Jujube tree

Drought phenomenon as a consequence of climate change may become a major limiting factor for agricultural systems, and its impacts on plant-insect interactions are only partially understood. Addressing this issue, life-history responses of the jujube lace bug were evaluated on jujube tree under three water treatments (control, moderate and severe drought stress). Performance responses of the jujube lace bug were evaluated under controlled conditions using arenas consisting of jujube leaves inside Petri dishes. Plant biochemical measurements showed that leaf chlorophyll a, b, and total chlorophyll content, were higher in moderate water stress treatment than other treatments while Total Soluble Solids, total carbohydrate, and proline concentrations were increased in drought stress. Also, the lowest amount of carotenoid, phosphorous, sodium content was measured in severe drought stress treatment. The life history responses of Monosteira alticarinata showed that mean oviposition period and life span were statistically higher on moderate water stress than other treatments. The lowest intrinsic rate of increase (r), the finite rate of increase (λ), the net reproductive rate (R0), gross rate reproduction (GRR), total fecundity, and the highest doubling time (DT) were measured on severely drought stress treatment. An increase on the performance of the lace bug can be due to an increase on the chlorophyll, nitrogen, protein and free amino acids in moderate water stressed plants. However in severe stress it do worse. Overall, this study revealed that sap feeders benefit from moderate water stress.

Nutrient Concentration of African Horned Cucumber (Cucumis metuliferus L) Fruit under Different Soil Types, Environments, and Varying Irrigation Water Levels

The nutrient concentration of most crops depends on factors such as amount of water, growing environment, sunlight, and soil types. However, the factors influencing nutrient concentration of African horned cucumber fruit are not yet known. The objective of the study was to determine the effect of different water stress levels, soil types, and growing environments on the nutrient concentration of African horned cucumber fruit. Freeze-dried fruit samples were used in the quantification of β-carotene and total soluble sugars. The results demonstrated that plants grown under the shade net, combined with severe water stress level and loamy soil, had increased total soluble sugars (from 8 to 16 °Brix). Under the shade-net environment, the combination of moderate water stress level and loamy soil resulted in increased crude protein content (from 6.22 to 6.34% °Brix). In addition, the severe water stress treatment combined with loamy soil, under greenhouse conditions, resulted in increased β-carotene content (from 1.5 to 1.7 mg 100 g−1 DW). The results showed that African horned cucumber fruits are nutrient-dense when grown under moderate water stress treatment on the loamy or sandy loam substrate in the shade-net and open-field environments.

CONTROL OF DROUGHT STRESS IN TOMATO PLANTS USING SOME CULTURAL PRACTICES

In this study, tomato plants cv. Alisa were irrigated with three different amounts of water i.e. optimum amount which was the amount of water that added to raise soil field capacity (FC) from 70% (as re-irrigated tomato when FC drop to 70% is considered the most suitable irrigation regime) to 100% (T1), 66% (T2) and 33% (T3) of optimum water amount. Also, three different drought adaptable treatments were applied to tomato plants, i.e. drought pretreatment of seedlings (seedling priming), spraying plants with a reflecting antitranspirant (a suspension of calcium carbonate at concentration of 6%) or infected plants with arbuscular mycorrizal fungus, as well as control which was not treat with any of adaptable treatment. Decreasing amount of irrigation water applied decreased gradually plant height, fresh and dry weights of plant organs, leaflet area, No of days to the first anthesis (F50), fruit set percentage, relative water content (RWC), N, P and K and total carbohydrate contents in leaves, No of fruits/ plant, average fruit weight and early and total yields, than those of well-watered plants (T1). water deficit treatments (T2 & T3) enhanced root length, leaflet thickness, osmotic pressure (OP) in leaves, water use efficiency (WUE) and improved fruit quality i.e. increased vit. C, TSS, titratable acidity, and lycopene contents and fruit firmness in ripe fruits. In addition, water deficit treatments altered dry matter distribution in tomato plants as it enhanced dry mater partitioning to roots on the expense of above ground organs. All adaptable treatments used, often alleviated the detrimental effects of water deficit treated plants (T2&T3) as they promoted plant growth and productivity of both well watered and water stressed plants than those of untreated (control) plants. In most cases, spraying plants with the antitranspirant material gave the highest values of growth characteristics and yield and its components with well watered treatment (T1) and moderate water stress treatment (T2) but not with severe water stress treatment (T3). Using mycorrizal inoculation treatment gave the highest values of P content in leaves, and average fruit weight. Also it gave the second highest values (as average of the effect of the three water regimes) of plant growth, plant water relations and productivity characters alternately with drought pretreatment. In addition, mycorrizal treatment gave the highest total yield and highest total plant fresh and dry weights when combined with lowest water supply (T3) than those obtained by other two adaptable treatment.

ENHANCING DROUGHT TOLERANCE OF TOMATO PLANTS GROWN UNDER DIFFERENT IRRIGATION REGIMES BY SOME CULTURAL PRACTICES

Water scarcely is a common problem especially in arid and semi-arid areas of the world like the Mediterranean region. Therefore, enormous efforts directed to improve the adaptation of plants to use less irrigation water by increasing their tolerant and resistant to water deficit by different means. In this study, tomato plants cv. Alisa were irrigated with three different amounts of water i.e. optimum amount which was the amount of water that added to raise soil field capacity (FC) from 70% (as re-irrigated tomato when FC drop to 70% is considered the most suitable irrigation regime) to 100% (T1), 66% (T2) and 33% (T3) of optimum water amount. Also, three different drought adaptable treatments were applied to tomato plants, i.e. drought pretreatment of seedlings (seedling priming), spraying plants with a reflecting antitranspirant (a suspension of calcium carbonate at concentration of 6%) or infected plants with arbuscular mycorrizal fungus, as well as control which was not treat with any of adaptable treatment. Decreasing amount of irrigation water applied decreased gradually relative water content (RWC), No of fruits/ plant, average fruit weight and early and total yields, than those of well-watered plants (T1). The reduction in total yield was mainly due to the reduction of both fruit weight and fruit number. However, water deficit treatments (T2 & T3) enhanced water use efficiency (WUE) and improved fruit quality i.e. increased vit. C, TSS, titratable acidity, and lycopene contents and fruit firmness in ripe fruits. The increase in fruit quality traits by water stress could be interpreted on the base that plants grown under such conditions react by stimulate the secondary metabolism which increasing plant defense, the secondary metabolites involved sugars, organic acids, vitamins, carotenoids and etc. All adaptable treatments used, often alleviated (even partly) the detrimental effects of water deficit treated plants (T2&T3) as they promoted plant productivity of both well watered and water stressed plants than those of untreated (control) plants. The increase in total yield resulted from using adaptable treatments was mainly due to the increase in average fruit weight, and to lesser extent fruit number. Adaptable treatments also enhanced plant water relation (RWC &WUE) compared to those of untreated control, but they considerably reduced fruit quality traits. In most cases, spraying plants with the antitranspirant material gave the highest values of yield and its components particularly when combined with well watered treatment (T1) and moderate water stress treatment (T2) but not with severe water stress treatment (T3). Using mycorrizal inoculation treatment gave the highest values of average fruit weight, also it gave the second highest values of plant water relations and productivity characters alternately with drought pretreatment. In addition, mycorrizal treatment gave the highest total yield when combined with lowest water supply (T3) than those obtained by other two adaptable treatments.

Essential Oil Composition at Different Plant Growth Development of Peppermint (Mentha x piperita L.) Under Water Deficit Stress

Peppermint is one of the most important and commonly used medicinal and aromatic plants worldwide. Present experiment was conducted to evaluate the essential oil content and quantitative changes of the main components of peppermint plants at different stages of crop growth. Greenhouse pots with peppermint Plants (30, 60 and 90 days after transplanting) were subjected to three different field capacity (FC) irrigation conditions, i.e. no stress, mild stress (60±5 % FC) and moderate stress (40±5 % FC) for one month. Essential oil composition and accumulation in peppermint was differentþ by plant growth stage alterations. The proportions of some monoterpene such as menthofuran, limonene, and pulegone decreased as plant matured, while those of menthol, cineole, and neomenthol increased. Both mild and moderate water stresses changed the essential oil content. Essential oil content of plants subjected to mild stress increased while moderate water stress treatment caused a significant reduction in essential oil content in different plant growth stage. Moderate stress reduced the essential oil percentage and changed the essential oil profile. Menthone content decreased and menthofuran content increased under moderate stress. Also, relative proportions of sesquiterpenes increased with water stress.

The influence of water stress on growth, ecophysiology and ornamental quality of potted Primula vulgaris ‘Heidy’ plants. New insights to increase water use efficiency in plant production

Efficient irrigation practices are required to reduce the amount of water used. In this study, the effects of different irrigation regimes on changes in growth, ecophysiology and ornamental traits of potted Primula vulgaris ‘Heidy’ plants were investigated. Three experiments were carried out. In the first, the plants were either fully irrigated (100% of container capacity) or not. In the second, plants were watered to full irrigation (control), to 50% of the control (moderate water stress), to 25% of the control (severe water stress), or not irrigated and followed by a rehydration phase. Both experiments were conducted under controlled growth conditions. The third experiment was performed under common nursery conditions in an unheated and shaded greenhouse where plants were either irrigated with common irrigation practices (control), or with 66% of the control amount (moderate water stress), or with 33% of the control (severe water stress). In general, the percentage of senescent plants, the growth index, the number of leaves, and the aerial fresh and the dry weight were not affected by moderate water stress treatments. As expected, increasing water stress resulted in a general decrease in all studied gas exchange parameters. However, stressed plants were more efficient in using water than control plants, suggesting that stomata closed to cope with drought conditions without damaging photosynthesis events. The number of fully opened flowers during the growing season was highest in both control and moderately water stressed plants. In conclusion, moderate, but not severe, water stress could be imposed in P. vulgaris ‘Heidy’ pot production to reduce the water consumption, still maintaining plant ecophysiological performances and ornamental quality.

Co-regulation of water and K+ transport in sunflower plants during water stress recovery

16-day-old sunflower (Helianthus annuus L.) plants were subjected to deficit irrigation for 12 days. Following this period, plants were rehydrated for 2 days to study plant responses to post-stress recovery. The moderate water stress treatment applied reduced growth in all plant organs and the accumulation of K+ in the shoot. After the rehydration period, the stem recovered its growth and reached a similar length to the control, an effect which was not observed in either root or leaves. Moreover, plant rehydration after water stress favored the accumulation of K+ in the apical zone of the stem and expanding leaves. In the roots of plants under water stress, watering to field capacity, once the plants were de- topped, rapidly favored K+ and water transport in the excised roots. This quick and short-lived response was not observed in roots of plants recovered from water stress for 2 days. These results suggest that the recovery of plant growth after water stress is related to coordinated water and K+ transport from the root to the apical zone of the ​​stem and expanding leaves. This stimulation of K+ transport in the root and its accumulation in the cells of the growing zones of the ​​stem must be one of the first responses induced in the plant during water stress recovery.

Effect of Super Absorbent Polymer and Irrigation Deficit on Water Use Efficiency, Growth and Yield of Cotton

Sustainable use of water resources in agriculture is a necessity for many arid countries. In order to investigate the effect of water deficit, irrigation after 120 (control), 155 (moderate water stress) and 190 mm (sever water stress) pan evaporation and super absorbent polymer rates (SAP) (0, 30, 60 and 90 kg ha-1) on growth, yield and water use efficiency of cotton, an experiment was conducted as split plot based on a randomized complete block design with three replications. Moreover, the effect of water quality (distilled water and solutions of 0.25, 0.5, 0.75, 1 and 1.25% NaCl) was investigated on water holding capacity by SAP. Results revealed that moderate water stress (irrigation intervals of aprox. 15 days) along with 60 kg ha-1 SAP application was the best treatment in terms of growth and yield indices of cotton. The results for plant height, plant dry weight, boll number per plant and fiber yield in this treatment were 16, 28, 42 and 10% higher than control treatment, respectively. Water deficit and SAP application improved the water use efficiency (WUE) of cotton. The amount of WUE in moderate water stress treatment along with consumption of 60 or 90 kg ha-1 SAP was 26% higher than for control treatment. In addition, water holding capacity by SAP in distilled water treatment was 7 times higher than in the case of 1.25% NaCl solution. The overall results showed that irrigation deficit and SAP application are two appropriate strategies for crop production in areas affected by drought stress, especially if low saline water sources are used.

Effect of Super Absorbent Polymer and Irrigation Deficit on Water Use Efficiency, Growth and Yield of Cotton

Sustainable use of water resources in agriculture is a necessity for many arid countries. In order to investigate the effect of water deficit, irrigation after 120 (control), 155 (moderate water stress) and 190 mm (sever water stress) pan evaporation and super absorbent polymer rates (SAP) (0, 30, 60 and 90 kg ha-1) on growth, yield and water use efficiency of cotton, an experiment was conducted as split plot based on a randomized complete block design with three replications. Moreover, the effect of water quality (distilled water and solutions of 0.25, 0.5, 0.75, 1 and 1.25% NaCl) was investigated on water holding capacity by SAP. Results revealed that moderate water stress (irrigation intervals of aprox. 15 days) along with 60 kg ha-1 SAP application was the best treatment in terms of growth and yield indices of cotton. The results for plant height, plant dry weight, boll number per plant and fiber yield in this treatment were 16, 28, 42 and 10% higher than control treatment, respectively. Water deficit and SAP application improved the water use efficiency (WUE) of cotton. The amount of WUE in moderate water stress treatment along with consumption of 60 or 90 kg ha-1 SAP was 26% higher than for control treatment. In addition, water holding capacity by SAP in distilled water treatment was 7 times higher than in the case of 1.25% NaCl solution. The overall results showed that irrigation deficit and SAP application are two appropriate strategies for crop production in areas affected by drought stress, especially if low saline water sources are used.

Effect of Storage Temperatures on Color of Tomato Fruit (Solanum Lycopersicum Mill.) Cultivated under Moderate Water Stress Treatment

Abstract Moderate water stress tomato cultivated hydroponically in the greenhouse contains high lycopene and very sensitive to storage temperatures. This study aimed to observe the effect of storage temperatures on the lycopene content and color quality parameters of tomato (both moderate water stress and no water stress tomato). The lycopene content of water stress tomato increased with the temperatures higher than 10 °C while no water stress tomato relatively stable or increased slightly. The lightness (L*) value of water stress and no water stress tomato decreased during storage in 10, 15, 25 and 30 °C temperatures. The redness (a*), yellowness (b*), a*/b*, hue (h), and chroma (C*) remained stable after 4 days storage in those temperatures. Storage with temperatures above 15 °C increased the color parameters value of both water stress and no water stress tomato. Moderate water stress treatment increased the redness color and harvesting tomato in ripening stage will only shows lightness (L*) major change during storage.

Variability of mesophyll conductance in grapevine cultivars under water stress conditions in relation to leaf anatomy and water use efficiency

Background and Aims Stomatal (gs) and mesophyll conductance (gm) limit photosynthesis significantly and consequently, apart from gs, gm is also a physiological process that could affect leaf water use efficiency (WUE). The aims of the present study were to analyse the genetic variability of gm in the grapevine, to relate the variability of leaf WUE with relative changes in gs and gm and to analyse the importance of leaf structural parameters in the variability of gm. Methods and Results The gm in seven potted grapevine cultivars (Vitis vinifera L.) were compared in three experiments under irrigation and moderate water stress treatments. Significant variability of gm was observed among cultivars associated with change in intrinsic WUE. No clear relationship with anatomical traits was found. Conclusions Variability of gm was associated with leaf WUE, although it could not be explained by anatomical variability. It is likely that biochemical mechanisms play an additional important role in the diffusion of CO2 in grapevines. Significance of the Study This study shows that the variability of gm in different grapevine cultivars offers a potential target for improving leaf WUE by increasing net photosynthesis (AN) without increasing plant water losses.

The effect of water deficit and sowing date on yield components and seed sugar contents of sweet corn (Zea mays L.)

Considering the little amount of research on this crop in Iran and especially in Kermanshah, this paper was devoted to its study. In order to study the effect of sowing date and water stress on yield and yield components and seed sugar content in sweet corn cv.SC403, an experiment was conducted in the research farm and laboratories of the department of agronomy and plant breeding at Razi University, Kermanshah, in 2008. This investigation was performed as a factorial experiment based on randomized complete block design (RCBD) with four replications. The sowing date factor included four dates (4 May, 24 May, 13 June and 3 July) and three levels of water stress (control, moderate and severe water stress). The accumulated evaporation included: 70 (control), 120 (moderate water stress) and 170 (severe water stress) from evaporation pan class A. With respect to the results of this experiment, if the purpose in sowing of sweet corn is quantitative yield, the 3rd of July under no water stress treatment (control) will be the best date (8547.2 kg ha-1). The sowing date of 3rd July and the moderate water stress treatment did not have significant effect on quantitative yield. Thus, in arid and semi arid areas such as Kermanshah where water saving is important, this sowing date maybe very useful for water saving. But if the purpose is to have high qualitative yield in sweet corn (seed sugar), the sowing date of 4 May under severe water stress (1.48% sucrose) maybe the best choice. Key words: Seed sugar content, sowing date, sweet corn, water stress, yield components.

ネイハキンカンの着花に及ぼす土壌乾燥処理の影響

Effect of water stress on flowering of ‘Meiwa’ kumquat trees (Fortunella crassifolia Swingle) was examined to establish a cultivation system for the first-flush flowers. Water stress was established by withholding water until the soil water content reached 45% for moderate water stress treatment, and 35% for severe water stress treatment. Although three sequential flowerings were observed on the control trees, only one flowering was observed on the water-stressed trees. In the control plot, flowering of the first-flush flowers began on 28 June, and about 10 flowers opened per day. Flowering of the second-flush flowers began on 6 July and the number of flowers opened per day reached 300. In moderate water stress treatment, flowering began on 25 June, and lasted until late July without interruption. Therefore, it was difficult to distinguish between the first- to third-flush flowers. In severe water stress treatment, flowering of the first-flush flowers began on 28 June and the number of flowers opened per day reached more than 200. Water stress did not affect fruit growth or quality of fruit. These results indicate that the number of first-flush flowers increases under water stress after termination of new shoot growth and that the required duration of water stress is about 2 weeks.

Effects of water stress on photosystem II photochemistry and its thermostability in wheat plants

Modulated chlorophyll fluorescence, rapid fluorescence induction kinetics and the polyphasic fluorescence transients (OJIP) were used to evaluate PSII photochemistry in wheat plants exposed to water stress and/or heat stress (25-45°C). Water stress showed no effects on the maximal quantum yield of PSII photochemistry (F v /F m ), the rapid fluorescence induction kinetics, and the polyphasic fluorescence transients in dark-adapted leaves, indicating that water stress had no effects on the primary photochemistry of PSII. However, in light-adapted leaves, water stress reduced the efficiency of excitation energycapture by open PSII reaction centres (F' v /F' m ) and the quantum yield of PSII electron transport (Φ PSII ), increased the non-photochemical quenching (q N ) and showed no effects on the photochemical quenching (q P ). This suggests that water stress modified the PSII photochemistry in the light-adapted leaves and such modifications may be a mechanism to down-regulate the photosynthetic electron transport to match a decreased CO 2 assimilation. In addition, water stress also modified the responses of PSII to heat stress. When temperature was above 35 °C, thermostability of PSII was strongly enhanced in water-stressed leaves, which was reflected in a less decrease in F v /F m , q P , F' v /F' m , and Φ PSII in water-stressed leaves than in well-watered leaves. There were no significant variations in the above fluorescence parameters between moderately and severely water-stressed plants, indicating that the moderate water stress treatment caused the same effects on thermostability of PSII as the severe treatment. It was found that increased thermostability of PSII may be associated with an improvement of resistance of the O 2 -evolving complex and the reaction centres in water-stressed plants to high temperature.