Higher Water Use Research Articles

Hydraulic Traits and Non-Structural Carbon Responses to Drought Stress in Reaumuria soongorica (Pall.) Maxim. and Salsola passerina Bunge

Drought-induced plant mortality, resulting from either hydraulic failure or carbon starvation, is hypothesized to be modulated by the drought intensity. However, there is a paucity of research investigating the response strategies in desert shrubs under drought stress with different intensities. We transplanted potted Reaumuria soongorica (Pall.) Maxim. and Salsola passerina Bunge seedlings in the rain-out shelter, and implemented three water treatments: a control (well-watered, CK), a chronic drought (gradually less watered, CD), and a flash drought (not watered, FD). We then quantified plant physiological traits associated with water use and carbon assimilation. Both R. soongorica and S. passerina showed similar changes in water use and carbon characteristics under different drought treatments. Water use efficiency was not significantly changed, but embolism resistance was significantly lower in CD, and leaf specific conductivity and embolism resistance were significantly lower in FD compared to CK. Under the drought treatment, both shrubs had significantly lower hydraulic safety margins than CK, with FD being significantly lower than CD. Notably, FD had lower carbon assimilation and a lower leaf non-structural carbon concentration, but higher stem non-structural carbon concentration. The results of a principal component analysis showed that net photosynthetic rate, sapwood specific conductivity, embolism resistance, midday water potential, and leaf and stem soluble sugar concentration were the main axes of variation for R. soongorica traits. CK had the highest water use efficiency, net photosynthetic rate, and gas exchange rate, while FD had the lowest embolism resistance and highest osmoregulation. Midday water potential, leaf and stem soluble sugar concentration were the main axes of variation for S. passerina traits, and individual distribution under three water treatments was associated with drought tolerance traits. The findings suggest that species exhibit different response strategies for resistance to drought stress, with R. soongorica being drought-avoidant and S. passerina being drought-tolerant. These findings highlight the adaptive capacity of desert shrubs to water deficit and provide insights for assessing hydraulic failure and carbon starvation in desert shrubs.

C4 monocots and C4 dicots exhibit rapid photosynthetic induction response in contrast to C3 plants.

Considering the prevalence of ever-changing conditions in the natural world, investigation of photosynthetic responses in C4 plants under fluctuating light is needed. Here, we studied the effect of dynamic illumination on photosynthesis in totally 10 C3, C3-C4 intermediate, C4-like and C4 dicots and monocots at CO2 concentrations of 400 and 800 μmol mol-1. C4 and C4-like plants had faster photosynthetic induction and light-induced stomatal dynamics than C3 plants at 400 μmol mol-1, but not at 800 μmol mol-1 CO2, at which the CO2 supply rarely limits photosynthesis. C4 and C4-like plants had a higher water use efficiency than C3 plants at both CO2 concentrations. There were positive correlations between photosynthetic induction and light-induced stomatal response, together with CO2 compensation point, which was a parameter of the CO2-concentrating mechanism of C4 photosynthesis. These results clearly show that C4 photosynthesis in both monocots and dicots adapts to fluctuating light conditions more efficiently than C3 photosynthesis. The rapid photosynthetic induction response in C4 plants can be attributed to the rapid stomatal dynamics, the CO2-concentrating mechanism or both.

Effect of Irrigation and Nutrient Management Studieson Sesame (Sesamum indicum L.)

Aim: To study the effect of Irrigation and nutrient management studieson Sesame (Sesamum indicum L.) in red and laterite soil of Odisha. Study Design: Treatments included three irrigation levels (I1: 2 irrigations at 21 and 63 days after sowing, I2: 2 irrigations at 21 and 42 days after sowing and I3: 3 irrigations at 21, 42 and 63 days after sowing ) are treated in main plot and four nutrient management (N1: 100% RDF, N2: 100% RDF + 2 t/ha FYM, N3: 100% RDF + 2 t/ha FYM + Jeevamrut @250 l/ha and N4: 75% RDF + 2 t/ha FYM + Jeevamrut @250 l/ha) are treated in sub plot were experimented in split plot design replicate thrice. Place and Duration of Study: A field experiment was conducted during Summer at khujimahal, Chandaka, Faculty of Agricultural Sciences, Siksha ‘O’ Anusandhan (Deemed to be University), Bhubaneswar Odisha. Results: The results showed that highest seed yield (643.49 kg ha-1), haulm yield (1820.13 kg ha-1) and harvest index (26.04%) was obtained in I3. N4 (75% RDF + 2 t/ha FYM + Jeevamrut @250 l/ha) showed second highest seed yield (652.21 kg ha-1), haulm yield (1882.07 kg ha-1) and harvest index (25.74%) which is at per with N3. Highest water use efficiency (2.72 kg ha-1 m-1) was calculated in I2N3. Conclusion: cultivation of sesame under75% RDF + 2 t/ha FYM + Jeevamrut @250 l/ha with 2 irrigations at 21 and 42 days after sowing proved better in terms of yield, economics and water use efficiency.

MYC2 regulates stomatal density and water use efficiency via targeting EPF2/EPFL4/EPFL9 in poplar.

Although polyploid plants have lower stomatal density than their diploid counterparts, the molecular mechanisms underlying this difference remain elusive. Here, we constructed a network based on the triploid poplar transcriptome data and triple-gene mutual interaction algorithm and found that PpnMYC2 was related to stomatal development-related genes PpnEPF2, PpnEPFL4, and PpnEPFL9. The interactions between PpnMYC2 and PagJAZs were experimentally validated. PpnMYC2-overexpressing poplar and Arabidopsis thaliana had reduced stomatal density. Poplar overexpressing PpnMYC2 had higher water use efficiency and drought resistance. RNA-sequencing data of poplars overexpressing PpnMYC2 showed that PpnMYC2 promotes the expression of stomatal density inhibitors PagEPF2 and PagEPFL4 and inhibits the expression of the stomatal density-positive regulator PagEPFL9. Yeast one-hybrid system, electrophoretic mobility shift assay, ChIP-qPCR, and dual-luciferase assay were employed to substantiate that PpnMYC2 directly regulated PagEPF2, PagEPFL4, and PagEPFL9. PpnMYC2, PpnEPF2, and PpnEPFL4 were significantly upregulated, whereas PpnEPFL9 was downregulated during stomatal formation in triploid poplar. Our results are of great significance for revealing the regulation mechanism of plant stomatal occurrence and polyploid stomatal density, as well as reducing stomatal density and improving plant water use efficiency by overexpressing MYC2.

Effect of different soil moisture regimes on yield and water use efficiency of groundnut at Kobo irrigation scheme, Kobo Ethiopia

In the arid and semi-arid part of Eastern Amhara, water is the most important yield-limiting factor for agricultural production. Application of the right amount of irrigation water at a right time helps to optimize water loss and increases crop yield. Therefore, a field experiment was conducted at Kobo irrigation scheme to determine the optimal crop water requirement and irrigation frequency for yield and water use efficiency of groundnut. The CROPWAT model could generate the 100% irrigation scheduling as 40 mm irrigation water with 8 days. Field base validation and ground truthing is vital. Therefore, the treatments were formulated by the factorial combinations of the three crop water levels as 75% ETc (30 mm), 100% ETc (40 mm), 125% ETc (50 mm) with three irrigation intervals (6 days, 8 days and 10 days). The treatments arranged in randomized complete block design with three replications. The statistical analysis was carried out using Genstat 15.0 software and the mean comparison was done using least significant difference (LSD) test. The analysis revealed that the crop water use efficiency was significantly (p<0.05) affected by the main effects of crop water levels, irrigation interval and by their interaction, whereas the grain yield does not show a significant (p>0.05) response. As the water levels declined and the irrigation intervals varied, the grain yield tends a fairly constant trend. However, based on the commerciality of the crop, application 75% ETc (30 mm) with 8 days irrigation interval gave numerically maximum grain yield of 3466.9 kg/ha and it has nearly more than 200 kg relative yield advantage over most treatments. The highest water use efficiency (0.9 kg/m3) was recorded from the combination 75% ETc (30 mm) with 10 days; while it was statistically at par with 75% ETc with 8 days interval (0.8 kg/m3) applied treatment. From the result, it could be concluded that the maximum yield and maximum water productivity were simultaneously achieved by combined application of 75% ETc with 8 days interval and saves 4600 m3 water to irrigate an additional 1.2 ha compared with 125% (50 mm) ETc with 6 days interval applied treatment.

Response of spring maize to irrigation scheduling and mulching in Punjab

Aim: This study was planned and conducted to find the optimum IW:CPE level of irrigation scheduling along with mulching for spring maize in Punjab. Methodology: An experiment was conducted in spring, 2022 on agriculture farm of Lovely Professional University, Punjab comprising of four levels of irrigation scheduling viz., I1 (Surface irrigation at critical growth stages), I2 (Surface irrigation at 1.0 IW:CPE), I3 (Surface irrigation at 0.8 IW:CPE), I4 (Surface irrigation at 0.6 IW:CPE) assigned to main plots and two mulching treatments viz., M1 (No Mulch), M2 (With Mulch) allotted to the sub plots, which were replicated 4 times in split plot design. Results: Application of irrigation at IW:CPE ratio of 1.0 and 0.8 in spring maize were equally good as they recorded higher growth and yield parameters. Among the mulching practices, M2 resulted in better growth and yield parameters over no mulching. Highest green cob yield, grain yield and stover yield were also attained under irrigation applied at 1.0 IW:CPE combined with mulching, but it remained statistically at par with irrigation at 0.8 IW:CPE with mulching. Highest water use efficiency was seen under 0.8 IW:CPE. Interpretation: Optimum level of irrigation along with mulching for spring maize was assessed based on the results obtained for growth, yield as well as water use efficiency. It was recorded that irrigation at 0.8 IW:CPE with mulching was found best for higher grain yield of maize hybrid. Key words: Grain yield, Hybrid maize, Irrigation scheduling, Mulching, Water use efficiency

Humic acid application on soil stability indices and enzyme activity at different bell pepper water requirements

Use of organic materials helps in reducing the consumption of chemical fertilizers, contributing to the sustainability of agricultural ecosystems. Humic acid can improve soil structure, especially in soils with low clay content, aiding in water retention and enhancing water absorption by plants. This characteristic has led to the attention of humic acid application in drought stress, particularly in arid soil regions. The present study aimed to investigate the simultaneous effects of humic acid and plant water requirements on the physical and biological properties of soil under bell pepper cultivation. The factorial experiment was conducted in a completely randomized block design with three levels of humic acid: 0 (HA0), 2 (HA2), and 4 (HA4) g/Kg of soil and four levels of plant water requirements: 60 (L60), 80 (L80), 100 (L100), and 120 % (L120), with four replications under greenhouse conditions. Bell pepper seedlings were transferred to 10 Kg pots after applying humic acid treatments and after the establishing of seedlings, plant water requirement treatments were applied for 80 days. During this period, plants were maintained at a temperature of 25 degrees Celsius during the day, 18 degrees Celsius at night, and a relative humidity of 75%, with a carbon dioxide concentration of 80 milligrams per liter. The results of this study showed that treatments L80HA4, L100HA4, and L120HA4 had the most significant impact on improving soil physical properties, such as normal stability index, total soil stability index, mean weight diameter of soil particles, soil particle stability, geometric mean diameter of soil particles, and reduction in soil particle destruction percentage. The highest values of wet and dry weight diameter of soil particles were observed in treatment L100HA4, which were 42.92%, 74%, and 67.01% higher, respectively, compared to the control (L60HA0). In contrast, the highest percentage of soil particle destruction was observed in treatment L60HA0, showing a 32.90% increase compared to treatment L100HA4. Furthermore, the best performance of bell pepper yield was observed in treatments L80HA4, L100H4, and L120HA4, although the differences between treatments were not statistically significant. The application of humic acid, in addition to improving bell pepper yield, increased water use efficiency and reduced water use. The lowest yield (3283 Kg/ha) and the lowest water consumption (3584 cubic meters/ha) were observed in treatments L60HA0 and L60HA4, respectively. Additionally, the results showed that the highest water use efficiency observed in L80HA4 treatment (7.45 Kg/m³), while the lowest was in L60HA0 treatment (0.80 Kg/m³). Moreover, humic acid significantly influenced the activity of soil enzymes, including soil phosphatase and urease. With more application of humic acid, soil moisture retention, microbial biomass carbon, urease, phosphatases activities increased. However, in treatments with full water requirements and 20 percent more than plant water requirements, enzyme activities decreased.

Effect of Deficit Irrigation on Wheat (Triticum aestivum L.) Yield and Water Use Efficiency in the Semi-Arid Region of Awash Basin, Ethiopia

Crop production is largely limited by water availability in arid and semi-arid regions of Ethiopia. Changing climate conditions and declining water resources demand appropriate approaches to improve crop yield and water use efficiency through a reduced and more reliable water supply. A field experiment was conducted to evaluate the effect of limited irrigation water use on bread wheat production and water use efficiency under the semi-arid climate conditions of Awash basin of Ethiopia. Five irrigation levels, that is, full irrigation (100% ETc/control), 85% ETc, 70% ETc, 55% ETc, and 40% ETc, were evaluated using a randomized complete block design (RCBD) with four replicates. Statistical analysis has shown a significant effect of irrigation levels on wheat grain yield, water use efficiency, economic profit, wheat grain quality, and aboveground biomass. The highest grain yield (5,085 kg ha−1) was obtained from 100% ETc irrigation application (i.e. 417.2 mm of water), and the lowest grain yield was obtained from 40% ETc (i.e. 223.7 mm of water) application. A deficit level of 85% ETc resulted in a yield that was comparable to that of full irrigation. Compared to other treatments, the 70% ETc application produced the highest water use efficiency (1.42 kg m−3). Using the saved water obtained from 70% ETc deficit irrigation application, 23.4% more wheat could be produced on 1.38 ha of land, resulting in the highest profit (US$2,563.9) and higher MRR (137%). The yield response factor and crop-water production function indicated that maintaining irrigation at optimal levels can prevent potential yield reductions. Consequently, a 70% ETc deficit irrigation application was found to be optimal for increasing wheat grain yield, water use efficiency, and economic benefits from irrigated wheat production. These results suggest that deficit irrigation for wheat under semi-arid climatic conditions is a viable irrigation management option for enhancing water use efficiency.

Growth, Yield, Water use Efficiency and Economic benefit for Brinjal as Influenced by Drip Irrigation in Western Ganga Catchment

This study was conducted in the College of Agriculture Sciences and Engineering, IFTM University, Moradabad, Uttar Pradesh (India). Drip irrigation, a relatively new technology in the world, has increased in vegetable crops. In India, eggplant, also known as brinjal, is cultivated across approximately 0.72 million hectares of land. The study included various drip irrigation treatments: T1 (1 hour every day), T2 (2 hours every two days), T3 (3 hours every three days), T4 (4 hours every four days), and T5 (Control with furrow irrigation). The findings showed that the best outcomes in terms of plant height, growth, yield, water use efficiency (WUE), benefit-cost ratio (B:C ratio), and economic returns were observed in T2, whereas T5 had the lowest values. The highest water use efficiency (WUE) was recorded in T2 at 327.29 kg/ha-mm through drip irrigation, while the lowest WUE in T5 was 169.88 kg/ha-mm through flood irrigation method. The maximum net return was obtained in treatment (T2) 163306 Rs/ha, while compared lowest net return at (T5) 101624 Rs/ha. Overall, the study underscores the significance of adopting modern irrigation technologies, particularly drip irrigation, to enhance agricultural productivity, conserve water resources, and improve the economic viability of vegetable crop cultivation, as evidenced by the superior results obtained in the treatment (T2).

Performance Evaluation of the Water Advisory for Irrigation Scheduling System (WAISS) Capacitance Soil Moisture Sensor

The agriculture sector accounts for 80% of the total freshwater resource use in the Philippines. With increasing competition for the scarce water supply, it is necessary to utilize water resources efficiently. The application of smart irrigation technology can help achieve higher water use efficiency, increase farm water productivity, and maximize crop yield. To minimize excess or insufficient irrigation water application to crops, and provide more effective and efficient water management, an integrated water monitoring system called Water Advisory for Irrigation Scheduling System (WAISS) was developed. The performance of WAISS was initially evaluated by comparing the soil moisture measurements of its capacitance soil moisture sensor with a commercially developed sensor and the standard gravimetric method. Statistical analysis shows that the low-cost WAISS soil moisture sensors are comparable with the commercially developed sensors with a Percent Error of 5.5% compared to METER ECH2O EC-5's 16.1%. This highlights WAISS' potential as a cost-effective yet reliable alternative for soil moisture monitoring.

Transpiration rates from mature Eucalyptus grandis × E. nitens clonal hybrid and Pinus elliottii plantations near the Two Streams Research Catchment, South Africa

Abstract. Pine plantations are the dominant species currently planted within the South African commercial forestry industry. Improvements in bio-economy markets for dissolving wood pulp products have seen an expansion in fast-growing Eucalyptus plantations due to their higher productivity rates and better pulping properties than pine. This has raised concerns regarding the expansion of Eucalyptus plantations and how they will affect water resources as they have been reported to have higher water use (quantified using transpiration rates) than pine. We measured transpiration rates (mm yr−1), diameter at breast height (quantified as quadratic mean diameter, Dq, m) and leaf area index of an 8-year-old Eucalyptus grandis × Eucalyptus nitens clonal hybrid (GN) and a 20-year-old Pinus elliottii. Transpiration rates were measured for two consecutive hydrological years (2019/20 and 2020/21) using a heat ratio sap-flow method, calibrated against a lysimeter. In the 2019/20 year, annual transpiration for P. elliottii exceeded GN by 28 %, while for the 2020/21 hydrological year, there was no significant difference between the transpiration of the two species, despite a 17 % and 21 % greater leaf area index for P. elliottii than GN in 2019/20 and 2020/21 measurement years respectively. Quadratic mean diameter increments were statistically similar (p > 0.05) in 2019/20, whereas the 2020/21 year produced significant differences (p<0.05). Tree transpiration is known to be influenced by climatic variables; therefore, a random forest regression model was used to test the level of influence between tree transpiration and climatic parameters. The soil water content, solar radiation and vapour pressure deficit were found to highly influence transpiration, suggesting these variables can be used in future water-use modelling studies. The profile water content recharge was influenced by rainfall events. After rainfall and soil profile water recharge, there was a rapid depletion of soil water by the GN trees, while the soil profile was depleted more gradually at the P. elliottii site. As a result, trees at the GN site appeared to be water stressed (reduced stem diameters and transpiration), suggesting that there was limited access to alternative water source (such as groundwater). The study concluded that previous long-term paired catchment studies indicate that eucalypts use more water than pine; however, periods of soil water stress and reduced transpiration observed in this study must be accommodated in hydrological models. Long-term total soil water balance studies are recommended in the same region to understand the long-term impact of commercial plantations on water resources.

Differences in photosynthetic and water use characteristics of four co-existing tree species at the treeline of the Japanese Alps

ABSTRACT Physiological characteristics of trees in the alpine treeline are critical for assessing the vulnerability of alpine forest ecosystems, but differences in water relations between co-existing deciduous and evergreen trees remain poorly understood. In this study, we analyzed the photosynthetic and water use characteristics of two deciduous broad-leaved (Sorbus matsumurana and Betula ermanii) and two evergreen coniferous (Abies mariesii and Pinus pumila) tree species at the treeline – i.e. the line connecting the highest patches of forest composed of trees at least three meters high – of Mt. Norikura in central Japan, to explore the physiological adaptations of trees to alpine environments. We monitored diurnal changes in leaf gas exchange rates and leaf and soil water potentials in each tree species during the growing season, as well as bulk leaf water relations based on pressure – volume curves and whole-tree hydraulic structures. The four species under study relied on different physiological characteristics at both leaf and plant levels for adaptation to their natural habitat. For maintaining water in leaves, S. matsumurana showed higher water use efficiency (WUE; the ratio of photosynthesis to transpiration) and osmotic adjustment. In contrast, B. ermanii showed lower WUE, while maintaining higher soil-to-leaf hydraulic conductivity with less stomatal control. In turn, A. mariesii showed higher WUE and leaf succulence. Meanwhile, P. pumila showed lower WUE but compensated for water loss through higher leaf hydraulic capacitance and tissue elasticity. Our observations demonstrate that tree species rely on specific physiological characteristics to adapt to the alpine treeline environment.

Engineering Crassulacean Acid Metabolism in C3 and C4 Plants.

Carbon dioxide (CO2) is a major greenhouse gas contributing to changing climatic conditions, which is a grand challenge affecting the security of food, energy, and environment. Photosynthesis plays the central role in plant-based CO2 reduction. Plants performing CAM (crassulacean acid metabolism) photosynthesis have a much higher water use efficiency than those performing C3 or C4 photosynthesis. Therefore, there is a great potential for engineering CAM in C3 or C4 crops to enhance food/biomass production and carbon sequestration on arid, semiarid, abandoned, or marginal lands. Recent progresses in CAM plant genomics and evolution research, along with new advances in plant biotechnology, have provided a solid foundation for bioengineering to convert C3/C4 plants into CAM plants. Here, we first discuss the potential strategies for CAM engineering based on our current understanding of CAM evolution. Then we describe the technical approaches for engineering CAM in C3 and C4 plants, with a focus on an iterative four-step pipeline: (1) designing gene modules, (2) building the gene modules and transforming them into target plants, (3) testing the engineered plants through an integration of molecular biology, biochemistry, metabolism, and physiological approaches, and (4) learning to inform the next round of CAM engineering. Finally, we discuss the challenges and future opportunities for fully realizing the potential of CAM engineering.

Effect of Irrigation Intervals, Irrigation Method and Different Nitrogen Fertilizer Rates on Wheat Performance and Water use Efficiency in Northern State of Sudan

Most soils under arid conditions have extremely low quality due to poor physical conditions, low organic matter and water retention capacity, soil fertility and consequently both low water and fertilizer use efficiencies. The present study was planned to investigate the effects of irrigation interval (II), irrigation methods (IM) and nitrogen fertilizer rates (NF) on wheat performance (yield and its components) and water use efficiency. The experiment was conducted at National Institute of Desert Studies Research Farm for two consecutive winter seasons of (2020/21) and (2021/22) in a sandy soil of North Sudan. The experiment design was complete randomized block in factorial arrangement with four replications. Factor (A) was irrigation methods with two types (furrow and basin), factor (B) was irrigation interval with three rates (7, 10, 13 days) and factor (c) was assigned to nitrogen with three rates (43, 86 and 129 Kg/fed). The results showed that irrigation methods had not significant p (≤.05) effect on wheat yield and its components and water use efficiency, irrigation interval affected significantly p (≤.05) on plant height, biomass, spike per meter square, grain yield and water use efficiency in both seasons Nitrogen fertilizer were effective highly significant p (≤.05) in improving biomass p (≤.05) and significantly p (≤.05) effect on plant height, number of spike per meter square, grain yield and water use efficiency in both seasons. Both irrigation interval and nitrogen fertilizer rates were not significant p (≤.05) effect on plant per meter. Maximum yield and high water use efficiency were obtained when irrigated every 7 days and added nitrogen fertilizer in rate of 129 Kg per fedan.

One size does not fit all: Different strategies employed by triticale and barley plants to deal with soil salinity

Salinity stress tolerance is a polygenic trait conferred by multiple physiological mechanisms, operating at various levels of plant structural organization. In this work, we have compared adaptative strategies employed by barley and triticale, two most tolerant cereal species, to deal with saline conditions. While the photosynthetic attributes were considerably reduced by 200 mM NaCl treatment in both species, triticale plants maintained higher photosynthetic capacity per unit leaf area compared with barley. Triticale plants also showed higher stomatal conductance under both saline and non-saline conditions, explaining the above photosynthetic rate. However, this high photosynthetic capacity in triticale was not translated into higher biomass (as compared with barley) due to stronger salinity-induced inhibition of tillering in the former species. Leaf elemental analysis revealed that salinity tolerance in triticale was related to its ability to exclude Na+ from the shoot while tolerant barley plant tended to accumulate more Na in shoot upon exposure to salt stress, for osmotic adjustment purposes. Salinity tolerance in both species was also causally associated with higher Fe content that was essential for activation of superoxide dismutase (SOD) to reduce the extent of oxidative stress. Electrophysiological experiments also revealed several patterns associated with control of ion transport in root epidermis, of which desensitization of K+- and Ca2+- ROS-inducible cation channels were the main trait conferring salinity tolerance. Cytosolic K+ retention in the root elongation zone in response to salt stress was more efficient in both triticale genotypes compared to barley. Finally, barley and salt tolerant genotypes of triticale showed higher speed of stomata, thus possessing higher water use efficiency.

Comparison of Physiological, Anatomical, and Morphological Traits between Sugarcane Hybrids and Their Parents with Different Stalk Dry Weights in the Early Growth Stage under Hydroponic Conditions

The high stalk weight sugarcane cultivar has a special mechanism to obtain greater growth, which was inherited from its parents. Thus far, comparisons of the high stalk weight sugarcane cultivar growth with its parents and cultivars with a low stalk weight have never been reported. The purpose of this research was to reveal the growth mechanism of the high stalk dry weight cultivar KK3 by comparing its physiological, anatomical, and morphological traits to those of a low stalk dry weight cultivar (UT12) and their four parental cultivars under hydroponic conditions. Their growth characteristics were evaluated at 15-day intervals from 30 to 90 days after planting. The root traits were measured at 2 months after planting (MAP), whereas the anatomical and physiological parameters were collected at 3 MAP. Biomass was recorded at 1, 2, and 3 MAP. KK3 had similar anatomical root traits to its female parent, whereas it had similar aboveground morphological traits to its male parent. The comparison between UT12 and its parents revealed that almost all its root anatomical traits were similar to the female parent, but it did not differ in leaf anatomy and root system size. Some physiological traits of KK3 were not different from those of its parents. In contrast, the net photosynthesis rate (PN), height, tiller number, stem dry weight, and stomatal density of UT12 were lower than those of its parent. For KK3, its small root stele and vessel size and high root length, surface area, and volume supported water uptake. The increase in stomatal density and decreased stomatal pore length may be appropriate characteristics for reducing water loss in this drought-resistant cultivar. Furthermore, KK3 exhibited a high water use efficiency (WUE) to promote biomass accumulation and growth despite its low transpiration and photosynthesis rates. This basic knowledge will be useful for selecting the parents based on their characteristics to create new sugarcane cultivars with a high stalk dry weight for drought stress during the early-growth-stage breeding programs and predicting their performance.

Grassland Greening and Water Resource Availability May Coexist in a Warming Climate in Northern China and the Tibetan Plateau

AbstractGreening of Northern China and the Tibetan Plateau (NCTP) has been observed by increases in the remotely sensed leaf area index (LAI), driven primarily by CO2 fertilization effects, anthropogenic warming, and the implementation of ecological restoration programs. Continued growth of LAI throughout the 21st century is also projected by the Coupled Model Intercomparison Project Phase 6 (CMIP6) scenarios. However, the question of whether local water resources can sustain ongoing grassland greening has not been adequately investigated. Here we assessed the sustainability of water resources under grassland greening across NCTP under various climate scenarios using water yield (WY, defined as precipitation minus actual evapotranspiration) as the key metric. Unexpectedly, we observe the coexistence of increases in LAI and WY in most of NCTP. In a warming climate with increasing precipitation and CO2, we find that grasses maintain high water use efficiency to sustain their growth, contributing to continued local water resource availability. Thus, livestock production may also continue to increase under the simultaneous growth of LAI and WY in the future.

Effect of Interval and Depth Irrigation on Water Use Efficiency, Cucumber Productivity under Green House Conditions and Drip Irrigation

A field experiment was conducted to study the effect of intervals and depths irrigation on water use efficiency and productivity of Cucumber under drip irrigation system. It was carried out during fall season 2021 in Al-Saqlawia, far about 45km southeast of Al-Ramadi, located at longitude 33° 24’ 57’' E and latitude 33° 24’ 57’' N. The experiment included two factors; the first is irrigation interval (I) which included two-days interval (I2) and four-days interval (I4). While the second one is irrigation depth which included 100% water depth and 50% water depth. The drip irrigation system was evaluated at operational pressure 50 kPa (0.5 bar) in order to determine the closest actual discharge to the design discharge, and calculating the uniformity coefficient and discharge variance. The results showed that 50kPa operational pressure gave an actual discharge of 3.94 Lh−1, which was the closest to the design discharge 4Lh−1, highest uniformity coefficient of 96.61% and lowest variance of 9.58%. While the highest yield achieved was 108 and 80-ton ha−1 at water depth (d50) for two irrigation interval 2 and 4 days compared to the lowest yield of 50 and 70-ton ha−1 at water depth (d100) for the same irrigation interval, respectively. While the highest water use efficiencies achieved was 20.9 and 15.48 kg m−3 at depth (d50) for 2-day and 4-day intervals, respectively. Finally, the best value for crop water consumptive use was obtained under drip irrigation system of 51.6 cm season−1.

Quantifying links between topsoil depth, plant water use, and yield in a rainfed maize field in the U. S. Midwest

Agricultural production in highly variable soils is a challenge, especially when those soils are shallow. Precision agriculture techniques were developed to improve yields and minimize spatial and interannual variability in profit. In the Central Claypan region of the Midwest United States, many of the precision agriculture techniques were based on the assumption that topsoil depth controlled plant available water, and therefore yield. But this assumption has not been empirically tested. In this study, we use measurements of sap flow installed on maize plants with a gradient in topsoil depth, caused by a claypan layer. We hypothesize that plants with higher water use have higher yield, plants in areas with thicker topsoil have higher water use, and soils in the areas with thicker topsoil have higher soil water content. Sap flow sensors were installed on 5 plants each at three locations with topsoil depths of 19.6 cm (shallow), 21.6 cm (medium), and 30.5 cm (deep) from June – September, 2022. An ANOVA analysis demonstrates that the average total season transpiration at the deep site (279 mm) was significantly larger than at the shallow site (151 mm), while the medium site was in the middle with transpiration not significantly different from either shallow or deep sites (218 mm). At the end of the season, the plants were harvested and total biomass and grain yield were measured. Increase in plant transpiration was significantly related to both increases in biomass and yield. Finally, we measured volumetric soil water content at each location and found higher soil water content at the site with thicker topsoil. Our results demonstrate the link between topsoil depth, soil water content, plant transpiration, and yield. These findings will help improve precision agriculture techniques in areas with highly variable topsoil thickness.

Changes in Blue/Green Water Partitioning Under Severe Drought

AbstractMuch attention has been given to the disproportionate streamflow deficits (relative to rainfall deficits) experienced by many catchments during the Millennium Drought (1998–2009) in southeastern Australia, along with lack of post‐drought streamflow recovery in some cases. However, mechanisms behind the coupled hydrologic and ecosystem dynamics are poorly understood. We applied a process‐based ecohydrologic model (RHESSys) in a Melbourne water supply catchment to examine changes in ecohydrologic behavior during and after the drought. Our simulations suggested that average transpiration (green water) was maintained under drought despite a substantial (12%) decrease in average rainfall, meaning that the entire rainfall deficit translated to reduced streamflow (blue water). Altered spatial patterns of vegetation behavior across the terrain helped the ecosystem maintain this unexpectedly high green water use. Decreased transpiration upland was compensated by increases in the riparian zone, which was less water limited and therefore able to meet higher water demand during drought. In the post‐drought period, we found greater transpiration and reduced subsurface water storage relative to pre‐drought, suggesting a longer‐term persistence in altered water partitioning. The post‐drought outcome was attributed to a combination of warmer climate and the persisting effects of the drought on nutrient availability. Given the importance of shifting ecohydrologic patterns across space, our results raise concerns for applying lumped conceptual hydrologic models under nonstationary or extreme conditions. Additionally, the processes we identified have important implications for water supply in Australia's second largest city under projected drying.