Biomass Water Use Efficiency Research Articles

Drought stimulus enhanced stress tolerance in winter wheat (Triticum aestivum L.) by improving physiological characteristics, growth, and water productivity

The impact of drought events on the growth and yield of wheat plants has been extensively reported; however, limited information is available on the changes in physiological characteristics and their effects on the growth and water productivity of wheat after repeated drought stimuli. Moreover, whether appropriate drought stimulus can improve stress resistance in plants by improving physiological traits remains to be explored. Thus, in this study, a pot experiment was conducted to investigate the effects of intermittent and persistent mild [65%–75% soil water-holding capacity (SWHC)], moderate (55%–65% SWHC), and severe drought (45%–55% SWHC) stress on the growth, physiological characteristics, yield, and water-use efficiency (WUE) of winter wheat. After the second stress stimulus, persistent severe drought stress resulted in 30.98%, 234.62%, 53.80%, and 31.00% reduction in leaf relative water content, leaf water potential, photosynthetic rate (Pn), and indole-3-acetic acid content (IAA), respectively, compared to the control plants. However, abscisic acid content, antioxidant enzyme activities, and osmoregulatory substance contents increased significantly under drought stress, especially under persistent drought stress. After the second rehydration stimulus (ASRR), the actual and maximum efficiency of PSII and leaf water status in the plants exposed to intermittent moderate drought (IS2) stress were restored to the control levels, resulting in Pn being 102.56% of the control values; instantaneous WUE of the plants exposed to persistent severe drought stress was 1.79 times that of the control plants. In addition, the activities of superoxide dismutase, peroxidase, catalase, and glutathione reductase, as well as the content of proline, under persistent mild drought stress increased by 52.98%, 33.47%, 51.95%, 52.35%, and 17.07% at ASRR, respectively, compared to the control plants, which provided continuous antioxidant protection to wheat plants. This was also demonstrated by the lower H2O2 and MDA contents after rehydration. At ASRR, the IAA content in the IS2 and persistent moderate drought treatments increased by 36.23% and 19.61%, respectively, compared to the control plants, which favored increased aboveground dry mass and plant height. Compared to the control plants, IS2 significantly increased wheat yield, WUE for grain yield, and WUE for biomass, by 10.15%, 32.94%, and 33.16%, respectively. Collectively, IS2 increased grain growth, yield, and WUE, which could be mainly attributed to improved physiological characteristics after drought-stimulated rehydration.

Endophyte-Mediated Populus trichocarpa Water Use Efficiency Is Dependent on Time of Day and Plant Water Status

Endophytes are potential partners for improving the resource use efficiency of bioenergy feedstock systems such as short rotation coppice Populus species. Endophytes isolated from members of the Salicaceae family have broad host compatibility and can improve water use efficiency (WUE) through decreases in stomatal conductance. However, the literature is inconsistent with regard to the environmental conditions and temporal patterns of these benefits. This study investigated how endophyte-mediated changes in Populus trichocarpa ‘Nisqually-1’ stomatal conductance and WUE shift with time and scale in response to water deficit stress. Leaf gas exchange and aboveground productivity were used to evaluate the carbon and water balance of greenhouse-grown plants in response to endophyte inoculation and water deficit. Differences in stomatal conductance between control and inoculated plants were more pronounced (39.7% decrease, Welch two-sample t [14.34 adjusted degrees of freedom] = –2.358, P = 0.033) under water deficit conditions in the late morning during a period of higher light intensity. The decrease in stomatal conductance accompanied a substantial increase in intrinsic WUE (iWUE) for water deficit inoculated plants. However, increases in iWUE did not result in improvements in aboveground productivity or shoot biomass WUE for water deficit inoculated plants. This decoupling between iWUE and aboveground productivity may be an indicator of assimilate allocation to microbial metabolism as an additional carbon sink or a shift in carbon allocation toward belowground biomass. Future work should take a whole plant approach that accounts for diurnal patterns in incident irradiance to evaluate the impact of endophyte inoculation on host WUE and stress tolerance.

Effects of Soil Moisture Conservation and Nutrient Management on Soil Water Content and WUE of Grain Sorghum (Sorghum bicolor L. Moench) in Eastern Ethiopia

Water and nutrients are the most constraining factors in sorghum production in semiarids of eastern Ethiopia. Combining soil moisture conservation and nutrient management practices may reduce these limitations. The study was carried out to explore the effects of combining soil moisture preservation and integrated nutrient management practices on soil water content and water-use efficiency (WUE) of grain sorghum. A split plot experiment was conducted at Babile and Erer districts amid the 2017 cropping season. Main plots were assigned to soil moisture conservation practices (flatbed and tied ridge) and the sub-plots were assigned to six nutrient combinations of 0N0P kg + t FYM; 46N10P kg + t FYM ha-1; 0N0P kg + 5 t FYM ha-1; 23N5P kg + 2.5 t FYM ha-1; 46N10P kg + 2.5 t FYM ha-1 and 23N5P kg + 5 t FYM ha-1. Treatments were randomized in a Randomized Complete Block Design with three replications. The sorghum variety 'Teshale' was used as a test crop. The results uncovered that both biomass and grain water-use efficiencies considerably improved with tied ridges coordinates with NP and FYM than other treatments. Tied ridges combined with 46N10P kg + 2.5 t FYM ha-1 and 23N5P kg + 5 t FYM ha-1 were way better than those of tied edges. The tied edges with 46N10P kg + 2.5 t FYM ha-1 (M5) as compared to unfertilized flatbeds, had brought about approximately 110 and 99% increment in biomass WUE and around 114 and 124% increment in grain WUE at Babile and Erer areas, respectively. Essentially, soil water content was higher for tied ridges amended with FYM and integrated NP and FYM as compared to other treatments. We, hence, concluded that combining moisture conservation impacts with the integrated nutrient amendment would improve soil water content and water-use efficiency of grain sorghum in eastern Ethiopia.

Wick irrigation improves seed yield and water use efficiency in mung bean

AbstractDrought is a serious threat to crop growth, and finding new irrigation methods can save water. This study was conducted to investigate water use efficiency and seed yield in mung bean under wick irrigation. Irrigation treatments consisted of the wick irrigation method, surface irrigation (common irrigation) with water equivalent to wick irrigation, and surface irrigation with the double water use of wick irrigation. The results showed that the wick irrigation had a seed weight per plant, 100‐seed weight, seed number per pod, pod number per plant, seed yield, biological yield, water use efficiency of seed, water use efficiency of biomass and net income increase of 164, 14, 28, 80, 164, 128, 164, 128 and 300%, respectively, compared to surface irrigation with an equivalent water volume of wick irrigation. Wick irrigation resulted in increases in plant height, internode length, leaf number per plant, node number per plant, branch number per plant, leaf length and leaf width of 60, 59, 65, 91, 91, 52 and 52%, respectively, compared to surface irrigation with an equivalent water volume of wick irrigation. In conclusion, the wick irrigation method, as a new method, can save water and improve seed yield and net income.

Effect of Different Macronutrient Supply Levels on the Drought Tolerance of Rainfed Grass Based on Biomass Production, Water Use Efficiency and Macroelement Content

Water shortage, one of the main limiting factors for plant growth and development, can be alleviated by an adequate nutrient supply. The effect of different nitrogen (N), phosphorus (P) and potassium (K) supply levels and their combinations was examined in different rainfall supply periods (wet, normal, dry) on a grass sward in a field experiment. Dry and fresh aboveground biomass production were primarily increased by the N–rainfall supply interaction, from 0.739 to 6.51 and from 1.84 to 21.8 t ha−1, respectively, but the P–rainfall supply and N–P interactions and K treatment all had significant effects. Dry matter content was primarily influenced by the N–rainfall supply interaction, increasing in response to N in dry periods and declining in wet periods. Water use efficiency (WUE) was increased by the N–rainfall supply interaction from 28.3 to 127 kg ha−1 mm−1, but the N–P interaction had a similarly strong effect, and K treatment increased it in the dry period. The N, P and K contents of the aboveground biomass were increased by treatment with the corresponding element, but were also influenced by rainfall supply. The increase in biomass, mainly due to N treatment, caused the dilution of the P and K contents in grass in treatments poorly supplied with P and K. Biomass production and WUE were significantly improved up to a dose of 200 kg ha−1 year−1 of N, up to a supply level of 153 mg kg−1 of P2O5, and 279 mg kg−1 of K2O measured in the soil. Treating grass with the N, P and K macroelements may effectively increase biomass production and water use efficiency, but above a certain level their application is unnecessary.

How is the water footprint of the species Vachellia farnesiana, Amburana cearensis, and Handroanthus impetiginosus influenced by abiotic stresses as water deficit and salinity?

In semi-arid regions, is necessary to explore strategies to mitigate abiotic stresses such as water deficit and salinity. This study aimed to evaluate the stress tolerance capacity of three species subjected to different water regimes and salinity levels, based on dry matter production and water use efficiency (WUE). The species Handroanthus impetiginosus, Vachellia farnesiana, and Amburana cearensis were evaluated in combination with different water regimes (50%, 75%, and 100% of reference evapotranspiration – ET0) and salinity levels (0.18, 1.50, and 1.90 dS m−1). The results show that biomass accumulation increased at 50% and 75% ET0, while the WUE decreased at 100% ET0. The salinity level (1.90 dS m−1) caused reductions in leaf dry biomass (LDB), total dry biomass (TDB), LDB/TDB ratio, and WUE. The negative effects of high salinity on plant height were greater with the application of 75% ET0. The highest WUE was obtained at 50% ET0 for A. cearensis and H. impetiginosus, while V. farnesiana obtained the highest WUE at 75% ET0. A. cearensis exhibited the highest biomass accumulation (2.58 g) and WUE (0.21 g L−1). Overall, the species can tolerate drought and salinity conditions, being sensitive to high salinity concentrations during their initial growth.

Above and below-ground growth, accumulated dry matter and nitrogen remobilization of wheat (Triticum aestivum) genotypes grown in PVC tubes under well- and deficit-watered conditions.

The continuing decline in water resources under the ever-changing climate compels us to re-orient our focus to a more sustainable practice. This study investigates the performance of Triticum aestivum wheat genotypes viz. HD-2967, HD-3086, HD-3249, DBW-187, and HD-3226 under well- and deficit-watered conditions for their root-traits, biomass and nitrogen accumulation and remobilization, and water use efficiencies, grown in PVC-tubes. The genotypes HD-2967, HD-3086, HD-3249, DBW-187, and HD-3226 under well-watered (WW) resulted in 36, 35, 38, 33, and 42% more grain yield compared to deficit-watered (DW). Among the genotypes, HD-3249 had the highest grain yield under both well- and deficit-watered conditions. Compared to DW, the WW had 28%, 30%, and 28% greater root length, biomass, and root length density at flowering {102 days (d), Z61}, while among the genotypes, HD-3249 had relatively greater root-traits. At flowering (Z61) and maturity (132d, Z89), genotypes under WW accumulated 30-46% and 30-53%, respectively greater shoot biomass over the DW. Furthermore, the shoot biomass remobilised for HD-2967, HD-3086, HD-3249, DBW-187, and HD-3226 under the WW was 32, 37, 39, 35, and 35% greater than the DW. The nitrogen partitioning to different plant parts at flowering (Z61) and maturity (Z89) was significantly greater with the WW than with DW. The total nitrogen- remobilized and contribution to grain-N under the WW was 55, 58, 52, 53, 58% and 9, 19, 15, 17, 17% greater than the DW for the genotypes HD-2967, HD-3086, HD-3249, DBW-187, and HD-3226. The irrigation water use efficiency (WUE) at flowering (Z61) was more under the deficit-watered, but the biomass and grain total WUE was improved with the well-watered condition. Hence, it is apparent that proper scheduling of irrigation and N applications, along with the adoption of a genotype suited to a particular environment, will result in better WUE and grain yields, along with better utilization of scarce resources.

Effect of Water Regime, Nitrogen Level, and Biostimulant Application on the Water and Nitrogen Use Efficiency of Wild Rocket [Diplotaxis tenuifolia (L.) DC

The use of biostimulants in agriculture is an emerging technique that can contribute to improved production and resource use efficiency. This research was carried out in southern Italy to evaluate the biostimulating effects of seaweed extract (SW) and azoxystrobin (AZ) on wild rocket subjected to two water regimes (WRs) and three nitrogen levels (NLs), and grown in pots under unheated greenhouse conditions. The following treatments were compared: (i) two WRs: restoration of 100% (WR100) and 50% (WR50) of crop evapotranspiration; (ii) three NLs: 0 (N0), 75 (N75), or 150 (N150) kg ha−1 of N; and (iii) three biostimulants (BSs): an untreated control (C), and the application of AZ or SW. This paper reports the effects on N uptake (Nup), N use efficiency (NUE), and water use efficiency (WUE). The following indicators of NUE were assessed: apparent recovery efficiency (RE), internal utilization efficiency (IE), partial productivity factor (PFPn) of N supplied, agronomic efficiency (AE), and physiological efficiency (PE). The following indicators of WUE were assessed: photosynthetic WUE (p_WUE), yield WUE (Y_WUE), biomass WUE (B_WUE), and irrigation yield WUE (IY_WUE). The indicators of NUE were affected differently by treatments. RE was 20% higher with SW. IE was higher with AZ. PFPn increased by 10.4 and 8.1% with AZ and SW, respectively. AE increased by 10.9 and 19.9% after applying AZ and SW, respectively. PE rose by 6.7 and 9.3% after applying AZ and SW. AZ and SW improved p_WUE, mainly under water deficit (interaction of WR × BS). With AZ application, Y_WUE, B_WUE, and IY_WUE were higher by 17.8, 13.8, and 19.3%, respectively, while the application of SW resulted in a smaller increase (9.5–7.7 and 9.9%). SW and AZ were shown to be effective through the moderate improvement of wild rocket’s nitrogen and water use efficiency. The two biostimulants were more effective at improving p_WUE in water deficit conditions, proving to be particularly useful for farmers operating with water scarcity. Therefore, they can provide valuable support to farmers by improving the sustainability of resource use.

Evaluation of Pre-Emergence and Post-Emergence Herbicides for Weed Management in Miscanthus sacchariflorus and Miscanthus sinensis

Miscanthus, is a promising bioenergy crop, considered superior to other bioenergy crops because of its higher water and nutrient use efficiency, cold tolerance, and higher production of biomass. Broadleaf weeds and grass weeds, cause major problems in the Miscanthus field. A field experiment was conducted in 2018 and 2019, to assess the effects of pre-emergence (alachlor and napropamide) and post-emergence herbicides (nicosulfuron, dicamba, bentazon, and glufosinate ammonium) on broadleaf and grass weeds in M. sinensis and M. sacchariflorus fields. The weed control efficiency and phytotoxicity of pre- and post-emergence herbicides were evaluated at 30 days after treatment (DAT) and compared to those of the control plots. The results showed wide variations in the susceptibility of the weed species to the treated herbicides. Treatment with nicosulfuron 40 g.a.i.ha−1 provided the most effective overall weed control (with 10% visual injury), without affecting the height and biomass of neither Miscanthus species in the field. Post-emergence herbicides such as glufosinate ammonium 400 g.a.i.ha−1 and dicamba 482 g.a.i.ha−1 were effective and inhibited the growth and density of the majority of weeds to a 100%; however, they showed significant phytotoxicity (toxicity scale of 1–10) to both species of Miscanthus. The application of glufosinate ammonium caused severe injuries to the foliar region (90% visual injury) of both Miscanthus sps. Comparatively, M. sinensis showed a slightly higher tolerance to the herbicides nicosulfuron, bentazon and napropamide with 10% visual injury at the recommended dose than M. sacchariflorus. The present study clearly showed that infestation of broadleaf and grass weeds in Miscanthus fields can cause significant damage to the growth and biomass of Miscanthus and applying pre-emergence and post-emergence herbicides effectively controls the high infestation of these weeds.

Impacts of CO2 Enrichment on Water Use Efficiency in Terrestrial Ecosystems: A Meta-Analysis of Experimental Manipulations

Elevated CO2 (eCO2) has important impacts on plants, especially on water use efficiency (WUE). A meta-analysis was performed to determine the responses of WUE to enriched CO2. We summarized 242 studies on WUE research under ambient and enriched CO2 conditions that were published between 1989 and 2019. Our results showed that WUE had positive responses to elevated CO2 with an increase of about 46% and high heterogeneity. Elevated CO2 increased leaf, grain, biomass and whole plant WUE by 76%, 9%, 30% and 37%, respectively. The effect size on leaf WUE was higher than the other three WUE types, and the effect size on whole plant WUE was higher than grain WUE (P<0.05). In another respect, the response of WUE in forests was higher than in cropland (P<0.05). Regarding different experimental methods, WUE had a stronger response to elevated CO2 by the method of climate-controlled chamber than by the methods of OTC (Open Top Chamber) or greenhouses (P<0.05). However, the effect size obtained by the method of greenhouse was higher than that obtained by the methods of either OTC or climate chamber for whole plant WUE (P<0.05). Furthermore, our results found WUE had a positive linear relationship with the magnitude of CO2 enrichment (P<0.05). Meanwhile, the effect size of elevated CO2 on grain WUE had a positive linear relationship with the duration of CO2 enrichment. This study found that the impacts of CO2 enrichment on WUE are unique and specific for different WUE types and the various experimental conditions.

Effects of foliar biofertilization on the Water Use Efficiency in different varieties of basil (Ocimum basilicum L.)

Introduction. Basil (Ocimum basilicum L.) is a little-known crop in the Bolivian highlands as its response to water use efficiency (WUE) in a Walipini-type greenhouses. Objective. To evaluate the behavior of two varieties of basil and the water use efficiency (WUE) in the application of foliar biofertilizer in a Walipini-type greenhouse. Materials and methods. The experiment was installed at the Ventilla Ecological Farm, in the Central Highlands of Bolivia, with an experimental period of 135 days (July 13 to November 25), 2014. A factorial experiment with two factors (varieties: Nufar F1 and Italian Large Leaf) and two levels of foliar biofertilizer (Biol) was used under a completely randomized block design. Results. Through the WUE, specific leaf area, and net assimilation rate relationship, it was observed that basil had a better development in Walipini-type greenhouse (underground greenhouse) since biomass accumulation was not significantly affected. The results showed that the production of basil in this environment using foliar biofertilizer, Biol, differ mainly by the variety rather than by the doses of Biol, showing that Nufar F1 had better development. Conclusion. A significant relationship was observed between Nufar F1 and Italian large Leaf for biomass weight when applying Biol at two different levels. It shows that there does not necessarily have to be a positive and significant relationship between biomass accumulation and WUE, so it is presumed that basil can develops regularly in Walipini-type greenhouses under semi-arid region conditions.

Interaction between soil water and fertilizer utilization on maize under plastic mulching in an arid irrigation region of China

Plastic film mulching (PM) has become a widely used cropping method in arid and semiarid areas. However, it is unknown how different PMs affect crop water and N utilization and their interaction under different N supplies. A two-year field experiment was conducted in the Hetao Irrigation District (HID), in northwest China. Following local irrigation practices, 500 mm border irrigation was used to grow spring maize over two growing seasons (2019 and 2020) with two N levels: high-N (225 kg N ha–1) and low-N (150 kg N ha–1). Combined with three mulching methods, the experiment had five treatments: (i) no mulching with high-N (control, CK), (ii) black plastic film with high-N (HB), (iii) transparent plastic film with high-N (HT), (iv) black plastic film with low-N (LB), and (v) transparent plastic film with low-N (LT). The 4 PM treatments had higher average soil water storage (0–120 cm) than CK. The PM treatments had the highest water consumption coefficients (Kwcn) at 6–leaf to 12–leaf stage (Kwc2) and milking to maturity (Kwc5) stage. The HP treatments (HB and HT) had higher soil nitrogen storage than CK during the growth period. Averaged across two seasons, HB and HT had 23.9%, 29.2% respectively, higher grain yields than CK. Averaged across two seasons, the transparent PM treatments had 7.49%, 5.31%, and 1.72% higher water use efficiency (WUE), partial factor productivity of nitrogen (PFPN), and harvest index, respectively, than the black PM treatments. The PM treatments showed the relationship between water use efficiency of biomass (WUEb) and nitrogen use efficiency of biomass (NUEb), with WUEb increased, NUEb also increased. Given these results, we recommend the high-N level and transparent PM for maize cropping to increase yield and resource utilization efficiency in the HID.

Variation in actual corn (Zea mays L.) evapotranspiration, single, and dual crop coefficient under different point source irrigation systems in a semiarid region

Close management of irrigation could have considerable impacts on water resources, especially for cropping systems dominated by corn. The experiment was carried out to compare the influence of porous capsule irrigation (PCI), surface drip irrigation (DI), and subsurface drip irrigation (SDI) systems, with or without mulching, on actual evapotranspiration (ETc act), crop coefficients (Kc single and Kc dual), biomass yield, and water use efficiency (WUE) of corn in a semiarid region of Iran. The experiment was arranged in a split-plot design with the three irrigation systems assigned to the main plots and two mulching (with or without foil type) treatments (M1 and M2) assigned to the sub-plots. The corn ETc act varied significantly (P < 0.05) with the different irrigation systems, being (mm) 389.8 for PCI, 377.0 for DI, and 372.8 for SDI. The highest Kc average and Kcb (0.82 and 1.22) and the lowest Ke (0.12) were observed under the PCI system. The dry and wet biological biomass yields were highest (29.98 and 107 t/ha) under the PCI + M1 treatment, and the lowest (23.19 and 58.54 t/ha, respectively) were under the DI + M2 treatment. The highest WUE (7.89 kg/m3) was also observed under the PCI + M1 treatment; PCI produced the best biological biomass yield, WUE and IWUE in comparison to DI and SDI systems. Accordingly, the PCI system could be a viable alternative to drip irrigation for areas with scarce water resources, particularly for smallholder farmers.

Assessing Growth and Water Productivity for Drip-Irrigated Maize under High Plant Density in Arid to Semi-Humid Climates

Determining the water productivity of maize is of great significance for ensuring food security and coping with climate change. In 2018 and 2019, we conducted field trials in arid areas (Changji), semi-arid areas (Qitai) and semi-humid areas (Xinyuan). The hybrid XY335 was selected for the experiment, the planting density was 12.0 × 104 plants ha−1, and five irrigation amounts were set. The results showed that yield, biomass, and transpiration varied substantially and significantly between experimental sites, irrigation and years. Likewise, water use efficiency (WUE) for both biomass (WUEB) and yield (WUEY) were affected by these factors, including a significant interaction. Normalized water productivity (WP*) of maize increased significantly with an increase in irrigation. The WP* for film mulched drip irrigation maize was 37.81 g m−2 d−1; it was varied significantly between sites and irrigation or their interaction. We conclude that WP* differs from the conventional parameter for water productivity but is a useful parameter for assessing the attainable rate of film-mulched drip irrigation maize growth and yield in arid areas, semi-arid areas and semi-humid areas. The parametric AquaCrop model was not accurate in simulating soil water under film mulching. However, it was suitable for the prediction of canopy coverage (CC) for most irrigation treatments.

Soil Water Availability Changes in Amount and Timing Favor the Growth and Competitiveness of Grass Than a Co-dominant Legume in Their Mixtures.

The grasslands on the semi-arid Loess Plateau of China are expected to be particularly responsive to the size and frequency changes of extreme precipitation events because their ecological processes are largely driven by distinct soil moisture pulses. However, the plant growth and competitiveness of co-dominant species in response to the changes in the amount and timing of soil water are still unclear. Thus, two co-dominant species, Bothriochloa ischaemum and Lespedeza davurica, were grown in seven mixture ratios under three watering regimes [80 ± 5% pot soil capacity (FC) (high watering), 60 ± 5% FC (moderate watering), and 40 ± 5% FC (low watering)] in a pot experiment. The soil water contents were rapidly improved from low to moderate water and from moderate to high water, respectively, at the heading, flowering, and maturity stages of B. ischaemum, and were maintained until the end of the growing season of each species. The biomass production of both species increased significantly with the increased soil water contents, particularly at the heading and flowering periods, with a more pronounced increase in B. ischaemum in the mixtures. The root/shoot ratio of both species was decreased when the soil water availability increased at the heading or flowering periods. The total biomass production, water use efficiency (WUE), and relative yield total (RYT) increased gradually with the increase of B. ischaemum in the mixtures. The relative competition intensity was below zero in B. ischaemum, and above zero in L. davurica. The competitive balance index calculated for B. ischaemum was increased with the increase of the soil water contents. Bothriochloa ischaemum responded more positively to the periodical increase in soil water availability than L. davurica, indicating that the abundance of B. ischaemum could increase in relatively wet seasons or plenty-rainfall periods. In addition, the mixture ratio of 10:2 (B. ischaemum to L. davurica) was the most compatible combination for the improved biomass production, WUE, and RYTs across all soil water treatments.

Lengthening single-stem rotation improves biomass yield and water use efficiency in black poplar genotype multi-stem rotation coppice plantations

Poplar short rotation coppice (SRC) plantations have great potential for supplying environmentally friendly bio-based industries. However, little research has focussed on the linkages between SRC management regimes and the consumption of water for biomass production in the Mediterranean environment. Therefore, we compared six hybrid clones and four native black poplar genotypes with an aim to examine how two different lengthening periods (3 vs. 5 years) of single-stem rotation affected growth performance in the following three years of multi-stem rotation coppice. To achieve this goal, we assessed the aboveground dry biomass production and variation in water use efficiency (WUE) of the genotypes annually. A longer single-stem rotation increased biomass productivity and WUE in the multi-stem rotation of the native black poplar, rather than that of the hybrid genotypes. In contrast, biomass and WUE performances did not diverge between the native and hybrid genotypes under the shorter single-stem phase. These findings underline the importance of lengthening the rotation of single-stem SRC plantations in hot and dry Mediterranean climates. Native black poplar genotypes managed in SRC should be strongly considered as environmentally compatible genetic resources both in protected areas and in areas where water supply constrains biomass production.

Growth and physiological responses of cotton plants to salt stress

AbstractThe objective of this study was to investigate the growth and physiological responses cotton plants to salt stress. At seven leaf stage, cotton plants were subjected to two treatments; 0 mM NaCl as the control and 150 mM NaCl as the salt stress treatment, respectively. The effect of salt stress on leaf gas exchange rates, leaf nitrogen concentration, chlorophyll content, leaf K+ and Na+ concentrations, plant water status, endogenous phytohormone concentrations, dry matter accumulation and partitioning in plant organs was evaluated. The results showed that salt stress significantly decreased plant growth, water consumption, leaf water relations characteristics and leaf gas exchange rates as compared to the control. Under salt, photosynthetic rate was reduced to less extend than did stomatal conductance (gs) and transpiration rate, resulting in greater intrinsic and instantaneous water use efficiencies compared to the control plants. gs decreased linearly with decreasing leaf water potential and leaf hydraulic conductance under salt. Salt‐stressed plants possessed a significant higher concentration of abscisic acid ([ABA]leaf), while a significantly lower concentrations of gibberellic acid ([GA3]leaf) and zeatin riboside ([ZR]leaf) in leaf than those grown under control. Negative linear relationships were found between gs and [ABA]leaf, ratio of [ABA]leaf to [GA3]leaf, ratio of [ABA]leaf to ([GA3]leaf+[ZR]leaf), respectively. Salt stress significantly decreased leaf K+ concentration, the ratio of K+/Na+ in leaf, shoot growth and biomass partitioning into leaf and stem, whereas increased leaf chlorophyll content, leaf nitrogen concentration and biomass partitioning into boll. Although the water use efficiency of plant biomass was unaffected, the water use efficiency of boll biomass was significantly enhanced by salt stress. Collectively, salt‐induced changes in both hydraulic and chemical properties were involved in mediating the leaf gas exchange response to salt stress, and the enhanced leaf nitrogen concentration and biomass partitioning into boll may lead to a sustained yield with less water consumption in cotton plants grown under moderate salinity stress.

Nitrogen fertilization strategies for improved Mediterranean rainfed wheat and barley performance and water and nitrogen use efficiency

Adequate fertilization strategies are paramount to fulfill increasing demands for food, feed and fiber while reducing environmental impacts. However, their optimization under Mediterranean no-till systems has received little attention. The objective of this work was to assess winter cereal yield and water and N use efficiencies in a rainfed semiarid Mediterranean climate under (i) a range of pre-plant fertilizers [control without N fertilizer (0 N), and the following at 75 kg N ha−1: mineral N (MIN), swine slurry (SS), poultry manure (PM), and compost (COM)], (ii) fertilizer incorporation: no-tillage without incorporating (NT) or incorporation with a vibrocultivator (INC) and (iii) application of urea-ammonium nitrate solution (UAN) as top-dress as a control without UAN (UAN-) or 50 kg N ha−1 (UAN+). The experiment covered six cropping seasons (2012–2019).Pre-plant applications had similar responses in crop yield, biomass, N uptake, grain N, water-use efficiency for biomass (WUEb), and water-use efficiency for yield (WUEy) but were greater than 0 N. The lack of differences between pre-plant fertilizers would be explained by the high amount of residual N and the mineralized N during the crop cycle. Top-dress UAN increased WUEy and crop yield in all the cropping seasons by an average of 587 kg grain ha−1, which represented 18 % of the total annual production. Averaged across variables and the growing seasons, INC reduced soil water content and WUEb by 10 % (from 24.3 to 21.8 kg ha−1 mm−1). Also, INC reduced grain yield by 9% (from 3799 to 3450 kg ha−1) by reducing the number of spikes m-2 produced, pointing out that INC resulted in water deficit during the early reproductive period of the crop. While INC is often consider a best management practice to reduce NH3 volatilization losses from broadcast fertilizer applications, the results demonstrate that in rainfed Mediterranean agroecosystems water is more limiting than the N that could be potentially lost by volatilization.

Effects of whole soil-plastic mulching system and fertilization rates on water consumption characteristics and yield of tartary buckwheat in arid land

<p indent=0mm>In order to study the effects of whole soil-plastic mulching planting and different fertilization rates on soil water consumption characteristics and yields of tartary buckwheat, a three-year (2015–2017) located experiment was carried out in semi-arid region of east-central Gansu Province, China, under whole soil-plastic mulching planting system. Four fertilization treatments under soil-plastic mulching were accordingly designed, including high application rate (HF, N <sc>120 kg</sc> hm^–2 + P₂O₅ <sc>90 kg</sc> hm^–2 + K₂O <sc>60 kg</sc> hm^–2), medium rate (MF, N <sc>80 kg</sc> hm^–2 + P₂O₅ <sc>60 kg</sc> hm^–2 + K₂O <sc>40 kg</sc> hm^–2), low rate (LF, N <sc>40 kg</sc> hm^–2 + P₂O₅ <sc>30 kg</sc> hm^–2 + K₂O <sc>20 kg</sc> hm^–2), and zero fertilization rate (ZF), whereas ZF with traditional non-mulching planting was set as the control (CK) to illustrate the effects of soil-plastic mulching and fertilization on water consumption characteristics, yields and water use efficiency (WUE) of tartary buckwheat in semi-arid area of China. The results showed that the effects of rainwater collection and soil moisture conservation were obvious after planting tartary buckwheat with whole soil-plastic mulching, which also improved soil water environment and increased pre-anthesis soil water storage (SWS, mm). LF was able to regulate soil water consumption before and after anthesis stage according to different precipitation years and soil moisture conditions. Compared with ZF, MF, HF, and CK in dry years, LF improved post-anthesis SWS by <sc>2.8–23.5 mm</sc> and increased crop pre-anthesis water consumption in the <sc>0–100 mm</sc> soil profile by <sc>26.3–32.4 mm</sc> in tartary buckwheat. As a result, LF increased total crop water consumption in the whole growth period by <sc>44.5 mm,</sc> and boosted water consumption module coefficient and intensity. Moreover, compared with ZF, MF, HF and CK, LF treatment increased dry matter weight at maturity stage by 1.2%–58.8%, leaf area index (LAI) at filling stage by 4.1%–68.5%, grain weight per plant by 1.6%–61.6%, plumpness rate by 0.6%–29.2%, biomass yield by 1.1%–182.5%, grain yield by 1.1%–130.4%, and water use efficiency (WUE, kg hm^–2 mm^–1) by 0.3%–102.7%, respectively. In conclusion, the storage effect of low amount fertilizer treatment for tartary buckwheat planting with whole soil-plastic mulching in dry land was obvious, which could achieve the coupling effects of soil moisture and fertilizer and regulate crop water consumption according to the environmental conditions such as precipitation during crop growth period, and it could significantly improve the biomass yield, grain yield and WUE of tartary buckwheat. Therefore, it was a suitable cultivation mode for yield-increasing and efficiency-boosting of tartary buckwheat in semi-arid area.

Soil water extraction pattern and water use efficiency of spring canola under growth-stage-based irrigation management

The rapid depletion rate of the Ogallala aquifer threatens agriculture sustainability in the U.S. Southern Great Plains (SGP). Adoption of drought tolerant crop with suitable irrigation strategy is critical to improve water use efficiency and sustain crop production in the region. The objective of the study was to assess soil water extraction pattern and water use efficiency of spring canola (Brassica napus L.) under deficit irrigation strategy (DI). Three diverse canola cultivars (‘H930’, ‘H955’ and ‘L140’) were grown under four different irrigation treatments; full-season irrigation (FI), no irrigation at the vegetative stage (VS), no irrigation at the reproductive stage (RS) and dryland (DL). Treatment VS extracted similar amount (20 mm) of total water from planting to harvest as FI in wetter year of 2015. However, VS extracted 10 mm of extra water from soil depth down to 1.6 m until harvest compared to FI in drier year of 2016. As water extraction during reproductive stage in 2016 was almost similar (70 and 67 mm in FI and VS, respectively) in VS and FI, most of the extra water extracted was utilized during vegetative stage when irrigation was skipped in VS. Canola sustained vegetative growth utilizing soil water extraction and efficiently utilized irrigation received during reproductive stage to reduce seasonal evapotranspiration (ET) in VS compared to FI. Treatment RS and DL also reduced seasonal ET, but they reduced average 11 and 13 % oil content compared to FI in 2015 and 2016, respectively. The VS had similar oil content as FI and optimized water use efficiency for biomass (WUEpb), and seed (WUEsy) and oil (WUEoy) yields. Among cultivars, L140 consistently had the greatest WUEpb in both experimental years and 34 and 36 % greater WUEsy and WUEoy in 2016 compared to both H930 and H955, respectively. Adopting spring canola cultivar L140 and skipping irrigation during vegetative stage could maximize water productivity in water deficit conditions of the SGP.