Effects Of Water Regime Research Articles

Effect of Water Regime and Organic Amendment on Agromorphological Parameters of Tomato (Solanum lycopersicum L.) Grown in the Open Field on Gleysol in Diabo Department, Central Côte d’Ivoire

The aim of the study was to improve the productivity of the PADMA 108 F1 tomato grown in the field on gleysol in the off-season by the combined application of a water regime and an organic amendment. The study took place in the off-season (July-August) in 2022 at Yomian-Kouadiokro (7°49N, 5°9W) in the Gbêkê region and Diabo department of central Côte d'Ivoire. The methodology consisted in clearing a hydromorphic fallow (a gleysol) of about 10 years and delimiting microplots in randomized Fisher blocks of 3 replicates. In each replication, 12 microplots of 5m2 were distributed in 3 blocks, each comprising 4 treatments (poultry manure and sawdust composts, NPK12-22-22 fertilizer and the no-fertilizer control). In each microplot, tomato seedlings were transplanted into 10 pots. At transplanting, fertilizers were applied as a basal fertilizer at a rate of 0.5Kg/pack (poultry droppings and sawdust) and 85g/pack of NPK at the foot of the tomato compared with the control. After planting, a regular watering of 60 liters of water was applied to each block using a watering can (10L), subjecting the seedlings to a specific watering regime of 7 waterings/week, 4 waterings/week and 2 waterings/week. The results showed a highly significant specific effect of watering 7 times/week and of the organic amendment (poultry droppings) on the agromorphological parameters with the highest values compared with the other treatments. On the other hand, the best values for tomato agromorphological parameters were obtained with the combined effect of watering 2 times/week with organic amendments (poultry manure compost), NPK 12-22-22 mineral fertilizer and sawdust compost to some extent. In conclusion, this study shows that to improve the productivity of the PADMA 108 F1 tomato in the ecosystem studied in the off-season, a watering regime of 2 waterings per week is appropriate, regardless of the type of treatment applied (organic or mineral fertilizers).

Genotype by environment interaction across water regimes in relation to cropping season response of quinoa (Chenopodium quinoa).

Genotype × environment (GxE) interaction effects are one of the major challenges in identifying cultivars with stable performance across agri-environments. In this study we analysed GE interactions to identify quinoa (Chenopodium quinoa) cultivars with high and stable yields under different soil moisture regimes, representing control conditions, waterlogging and drought. Waterlogging and drought treatments were artificially induced using normoxia, a combination of hypoxia-normoxia, and 10% PEG (Polyethylene glycol) under hydroponic growth conditions, respectively. Both waterlogging and drought conditions significantly reduced the plant height (PH), number of leaves (NoL) and number of branches (NoB), stem diameter (SD), leaf area (LA) and dry weight (DW) of quinoa genotypes. The genotype, water regime, and genotype by water regime effects all significantly affected the measured quinoa traits. Based on the additive main effects and multiplicative interaction (AMMI) model for DW, the genotypes G18, Puno, Q4, 2-Want, Puno, Real1 x Ruy937 and Titicaca were found to exhibit tolerance and were stable across water regimes. A second-stage evaluation was conducted to test genotype × environment interaction effects in crop production field trials, selecting two contrasting seasons based on soil moisture conditions involving a diverse set of genotypes (58 varieties in total). Our results demonstrate significant variations in both growth and yield among the quinoa genotypes across the cropping seasons. The GGE analysis for grain yield indicate that field conditions matched to G × E under hydroponic experimental conditions and the cultivars G18, Q1, Q4, NL-3, G28, 42-Test, Atlas and 59-ALC were classified within a range of high productivity. Our findings provide a basis for understanding the mechanisms of wide adaptation, while identifying germplasm that enhances the water stress tolerance of quinoa cultivars at early growth stages.

Interaction Effects of Water and Nitrogen Practices on Wheat Yield, Water and Nitrogen Productivity under Drip Fertigation in Northern China

Water resource shortage and unreasonable application of nitrogen (N) fertilizer have been problems in wheat production of northern China. However, the interaction effects of water regimes and N practices on wheat root growth, grain yield, soil water, and inorganic N changes as well as water-N use efficiency are still unclear under drip irrigation. A field experiment was conducted during the 2020–2021 and 2021–2022 winter wheat (Triticum aestivum) growing seasons. In this study, three irrigation schedules (i.e., irrigation was applied up to 80% [D1], 75% [D2], and 70% [D3] as soon as the soil water content decreased to 65%, 60% or 55% of field capacity) and two N practices (i.e., N applied at the base, jointing, booting stages were 90, 72, 48 kg ha−1 [N1], and the base, jointing, booting, filling stages were 90, 40, 40, 40 kg ha−1 [N2], respectively) were considered. The decease in irrigation water amount was offset by the increase in soil water consumption. In addition, N practices significantly interacted with irrigation on soil NO3−–N accumulation (2021–2022), NH4+–N accumulation, SPAD value (2020–2021), N content in stems and grains at maturity, and average root length and weight density at the flowering stage. Irrigation, rather than N practices, significantly affected grain yield, total N uptake, crop N transformations (NT), the contribution of NT to grain (NTPC), water and N productivity, in which, for the value of these two seasons, D2 increased total N uptake by 18.1% (p < 0.05), and NT by 39.4% (p < 0.05) under N1 as compared to D3. Additionally, the highest WUE and ANUE were found in D2 during 2021–2022. Heavy irrigation water amount caused high a LAI; further analysis proved that the LAI was the key factor affecting grain yield, and positively and significantly correlated to yield. However, no significant difference in the LAI between D1 and D2 was found. N1 was beneficial to prevent N leaching and increase water and N use efficiency, biomass, and N transformation amount. This study recommends that D2 + N1 might be a promising system for manipulating irrigation and fertilization practices under sub-surface drip irrigation systems to improve water and N use efficiency and grain yields in semi-arid regions.

Effect of water regimes and weed-management practices on growth, yield and weed-control efficiency of rice under system of rice intensification

A field experiment was conducted during the rainy (kharif) seasons of 2012 and 2013 at Khudwani, Jammu and Kashmir, to evaluate the effect of water regimes and weed-management practices on growth and yield of rice (Oryza sativa L.) grown on silty clay loam soil. The treatments comprised 3 irrigations schedules, viz. alternate wetting and drying (AWD), saturated conditions (SC) and continuous flooding (FL), and 7 weed-management op tions including 4 herbicidal treatments, viz. pyrazosulfuron ethyl @ 20 g/ha at 3 days after transplanting (DAT, W1 ); cyhalofop butyl @ 80 g/ha at 15 DAT (W2 ); pyrazosulfuron ethyl 20 g followed by (fb) cyhalofop butyl 80 g/ha at 3 and 15 DAT (W3 ); butachlor @ 1.5 kg/ha at 3 DAT (W4 ); 3 cono weeding at 15, 25 and 35 DAT (W5 ) along with weedy check (W6 ) and weed free (W7 ). The experiment was laid out in a split-plot design with 3 replications under SRI. The data revealed that significant higher growth parameters like leaf-area index (LAI), dry-matter accumula tion and tillers/plant and yield attributes, i.e. panicle length, panicles/m2, grains/panicle, panicle weight, grains/ panicles, 1,000-grain weight, and higher grain yield were recorded in saturated water regime. On an average a yield superiority of 2.2 and 5.8% was recorded by saturated water regime over AWD and continuous flooding. Among the herbicides tested, pyrazosulfuron-ethyl @ 20 g/ha (3 DAT) fb cyhalofop-butyl @ 80 g/ha (15 DAT) re sulted in significantly higher panicle length, panicles/m2, panicle weight, grains/panicles, 1,000-grain weight and higher grain yield comparable to the weedy check. The mean yield advantage recorded by the use of pyrazosulfuron-ethyl fb cyhalofop-butyl was 19.3, 14.0 and 10.3% over cyhalofop-butyl, cono-weeding and butachlor, respectively, during both the years of experimentation.

Water regime and fertilizer‐phosphorus source effects on greenhouse gas emissions from rice

AbstractGreenhouse gas (GHG) emissions from rice (Oryza sativa) systems have been correlated to water management practice, but to date, no study has directly evaluated three main GHGs (i.e., methane [CH4], nitrous oxide [N2O], and carbon dioxide [CO2]) under flood‐ and furrow‐irrigated conditions at the same time as affected by various fertilizer‐phosphorus (P) sources, in particular the reportedly slow‐release struvite‐P source. Therefore, the objective of this study was to evaluate the effect of water regime (flooded and furrow‐irrigated) and fertilizer‐P source (diammonium phosphate, chemically precipitated struvite, electrochemically precipitated struvite [ECST], triple superphosphate, and an unamended control) on GHG emissions and two‐ and three‐gas global warming potentials (GWP* and GWP, respectively) in the greenhouse. Methane emissions were 10 times greater (p < 0.05) under flooded (29.4 kg CH4 ha−1 season−1) than under furrow‐irrigated conditions (2.9 kg CH4 ha−1 season−1), and four times lower (p < 0.05) with ECST (3.4 kg CH4 ha−1 season−1) than other fertilizer‐P sources, while CO2 emissions were three times greater (p < 0.05) under furrow‐irrigated (23,428 kg CO2 ha−1 season−1) than under flooded (8290 kg CO2 ha−1 season−1) conditions. The GWP* under furrow‐irrigated conditions was almost 40% lower (p < 0.05) than under flooded conditions. Although N2O emissions were unaffected by fertilizer‐P source, the N2O contribution to GWP* was more than 80% under furrow‐irrigated conditions. Flood‐ and furrow‐irrigated water regimes require diversified approaches in GHG mitigation, where the best management for ECST needs to be more fully evaluated.

Effects of water regime and inoculation with arbuscular mycorrhizal fungi on mycorrhizal communities of roots of rice and pearl millet in upland and lowland fields

Effects of water regime and inoculation with arbuscular mycorrhizal fungi on mycorrhizal communities of roots of rice and pearl millet in upland and lowland fields

Investigating the influence of varying water regimes on the growth and development and nutritional water productivity of bush tea (Athrixia phylicoides DC.)

AbstractBush tea (Athrixia phylicoides DC.) is an indigenous shrub of South Africa known for its medicinal properties. However, due to a lack of comprehensive information to develop suitable irrigation management strategies, the cultivation of bush tea is currently limited to small‐scale operations. Considering this limitation, the current research investigated the effect of water regimes on the growth and development, yield, and nutrient content along with its nutritional water productivity (NWP) under field conditions. The treatment consisted of a crop water requirement (ETa) of 100%, 30%, and the control (stress) in a complete randomized block design (CRBD). Each treatment was replicated three times to ensure robustness and accuracy of the findings. Results demonstrated that the highest gravimetric moisture content readings were found in the control treatment and the lowest in the 100% treatment. Conversely, the 30% ETa treatment significantly (p < 0.05) impacted bush tea's growth, development, productivity, and NWP. However, it was observed that the 100% ETa treatment resulted in a higher biomass yield (259.1 kg/ha) compared to the 30% ETa treatment (171.2 kg/ha) and control (stress) (68.2 kg/ha). The water productivity exhibited notable differences across the varying water regimes. These findings contribute valuable insights for developing appropriate irrigation management strategies to overcome existing limitations in the scale of bush tea production. The research lays the groundwork for future studies and practical applications aimed to foster the sustainable cultivation of bush tea in South Africa.

Effect of Water Regime and Soil Maintenance Mode on Vegetative Growth and Peach Tree Production

The peach tree is a very water-demanding species that is affected by water stress, which is worsening due to global warming. The soil environment is also influenced by tillage and cropping methods, which affect the water content, temperature, aeration, and organic matter of the soil. Weed control is one of the most crucial cultural practices in arboriculture since weeds can compete with fruit trees for resources. This paper aims to measure the impact of water stress combined with different soil maintenance methods on vegetative growth and peach tree production. Different evapotranspiration conditions (ETc) were used. Two irrigation doses R1 (80% of ETc) and R2 (100% of ETc) were combined with three soil maintenance modes T1 (Sapping), T2 (Sickle tillage), and T3 (Chemical maintenance). The findings highlighted water stress reduces the growth and development of the peach tree but did not have a significant impact on yield when the irrigation dose was reduced by 20%. The sapping and sickle maintenance modes recorded the best results for most of the parameters, while the chemical maintenance mode had a positive effect on the total number of fruits and yield under the 100% of ETc water regime.

An analysis of the effects of water regime on grapevine canopy status using a UAV and a mobile robot

In this paper, we propose a novel approach for analyzing the effects of water regime on grapevine canopy status using robotics as an aid for monitoring and mapping. Data from an unmanned aerial vehicle (UAV) and a ground mobile robot are used to obtain multispectral images and multiple vegetation indexes, and the 3D reconstruction of the canopy, respectively. Unlike previous works, sixty vegetation indexes are computed precisely by using the projected area of the vineyard point cloud as a mask. Extensive experimental tests on repeated plots of Pinot gris vines show that the GDVI, PVI, and TGI vegetation indexes are positively correlated with the water potential: GDVI (R2=0.90 and 0.57 for the stem and pre-dawn water potential, respectively), PVI (R2=0.90 and 0.57), TGI (R2=0.87 and 0.77). Furthermore, the canopy volume and the canopy area projected on the ground are impacted by the water status, as well as stem and pre-dawn water potential measurements. The results obtained in this work demonstrate the feasibility of the proposed approach and the potential of robotic technologies, supporting precision viticulture.

Annual greenhouse gas emissions from a rice paddy with different water-nitrogen management strategies in Central China

Current water-nitrogen (N) management strategies are necessary to be improved to increase crop productivity while reducing environmental costs. However, the effects of improved water-N management strategies on paddy CH4 and N2O emissions simultaneously generated during the growing and non-growing seasons have not been explored. Therefore, in this study, four water-N management practices—urea plus conventional irrigation (UREA+CI), urea plus alternate wetting-drying irrigation (UREA+AWD), controlled-release N fertilizer plus CI (CRNF+CI), and CRNF plus AWD (CRNF+AWD)—were evaluated in a 3-year field experiment following a randomized complete block design with three replications each. The results demonstrated that during rice growing seasons, CH4 emissions significantly decreased by 12.6–44.9% under UREA+AWD and by 17.2–32.1% under CRNF+CI, compared to UREA+CI, respectively, and CRNF+SWD showed the highest mitigation potential. N2O emissions were reduced in CRNF treatments (CRNF+CI and CRNF+AWD) but increased by replacing CI with AWD during rice growing seasons, suggesting the potential effects of water regimes on N2O emissions. Furthermore, AWD and CRNF reduced CH4 emissions during the land preparation period before the late rice growing season and the fallow period, whereas CRNF treatments triggered the release of N2O in the fallow period. Moreover, there were no significant differences in soil organic carbon sequestration rates among the treatments. The results indicated that AWD, CRNF and their combination significantly reduced annual net total greenhouse gas emissions without yield loss. Collectively, this study unravels the potential of alternative water-N management strategies to improve rice yields while minimizing GHG emissions in double rice cropping systems.

Effects of Watering Regimes and Planting Density on Taro (Colocasia esculenta) Growth, Yield, and Yield Components in Embu, Kenya

Taro (Colocasia esculenta (L.) Schott) is one of the most underutilized crops in sub-Saharan Africa and an important staple food in the tropics. Understanding its growth response under selected watering regimes and planting densities underpins this research. A study was conducted at the Kenya Agricultural and Livestock Research Organization (KALRO), Embu Research Centre, during the long rains (LR) in 2021 and the short rains (SR) in 2021–2022. A factorial experiment with a split-plot layout arranged in a completely randomized block design was used. The main factor was the irrigation levels, while the subfactor was the planting density, with three replications. The three irrigation levels were at 100%, 60%, and 30% based on the field capacity (FC). The planting densities used were 0.5 m × 0.5 m (40,000 plants ha−1), 1 m × 0.5 m (20,000 plants ha−1), and 1 m × 1 m (10,000 plants ha−1), representative of high, medium, and low planting densities, respectively. Time and season ( P < 0.05 ) significantly influenced taro growth components (plant height, leaf area, leaf area index, and vegetative growth index) and yield components (corm length, corm diameter, corm mass, yield, and total biomass). Planting density influenced the leaf area and the leaf area index ( P < 0.05 ). The watering regime did not affect taro growth or yield components. Corm mass (0.59 kg), total biomass (49.8 t/ha), and yield (13.38 t/ha) were all the highest in the 30% FC. The 1 m × 0.5 m spacing produced the highest corm mass (0.62 kg). The high planting density (0.5 m × 0.5 m) resulted in the highest total biomass (70.2 t/ha), yield (20.84 t/ha), and harvest index (30.44%). As a result, the 0.5 m × 0.5 m planting density and 30% FC watering regime are recommended to farmers in the area for increased yields and food security.

Morphology, photosynthetic physiology and biochemistry of nine herbaceous plants under water stress.

Global climate warming and shifts in rainfall patterns are expected to trigger increases in the frequency and magnitude of drought and/or waterlogging stress in plants. To cope with water stress, plants develop diverse tactics. However, the adoption capability and mechanism vary depending upon the plant species identity as well as stress duration and intensity. The objectives of this study were to evaluate the species-dependent responses of alpine herbaceous species to water stress. Nine herbaceous species were subjected to different water stresses (including moderate drought and moderate waterlogging) in pot culture using a randomized complete block design with three replications for each treatment. We hypothesized that water stress would negatively impact plant growth and metabolism. We found considerable interspecies differences in morphological, physiological, and biochemical responses when plants were exposed to the same water regime. In addition, we observed pronounced interactive effects of water regime and plant species identity on plant height, root length, root/shoot ratio, biomass, and contents of chlorophyll a, chlorophyll b, chlorophyll (a+b), carotenoids, malondialdehyde, soluble sugar, betaine, soluble protein and proline, implying that plants respond to water regime differently. Our findings may cast new light on the ecological restoration of grasslands and wetlands in the Qinghai-Tibetan Plateau by helping to select stress-tolerant plant species.

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.

Effect of water regime, nitrogen level and biostimulants application on yield and quality traits of wild rocket [Diplotaxis tenuifolia (L.) DC.

Wild rocket is an expanding vegetable crop, especially as a fresh-cut product that requires high quality standards. These can be achieved through appropriate management of agronomic practices such as water supply and nitrogen nutrition, in combination with emerging techniques such as the application of biostimulating substances. Hence, this study is focused on evaluating the response of the wild rocket to the application of two biostimulants in relation to different water regimes and nitrogen levels. The combined effect of two watering regimes (WR) (restoration of 50% and 100% of crop evapotranspiration-ETc, named WR50 and WR100, respectively); three N levels (NL) (0, 75 and 150 kg ha-1 N, named N0, N75 and N150, respectively); two biostimulants (BS) based on seaweed extract (SW), Azoxystrobin (AZ) and an untreated control (C) are investigated. The split-split plot experimental design with three replicates was used by arranging WR in the main plots, NL in the subplots and BS in the sub-subplots. Experiment was carried out in an unheated greenhouse during two growth cycles. Water shortage caused root biomass/total biomass ratio (RR) increase by 11.3% and 31.1% drop in yield, mainly because of the reduction in leaf size and number. Total phenols (TP), total antioxidant activity (TAA), total carotenoids (TCa) and nitrate (Ni) content were higher in WR50 in respect to WR100 by 10.4%, 18.7%, 12.0%, and 35.5%, respectively, while total chlorophyll (TCh) was lower by 5.3%. The increase of NL between N0 and N150 raised yield (222%), TCh (32.5%) and Ni (288.3), but reduced RR (43%), TP (16.2%), TAA (21.4%) and TCa (31.0%). SW and AZ increased yield respectively by 10.3% and 16.9%, mainly because raised leaf number for SW and leaf size for AZ. Moreover, SW increased RR by 7.2%, while AZ reduced it by 17.2%. SW and AZ improved TP, TAA, TCh and TCa respectively by 8.8%, 13.1%, 10.2% and 23.8% and by 10.8%, 19.7%, 16.0% and 35.6%. BS reduced Ni content by 21.5 (SW) and 36.8% (AZ). SW and AZ have shown good biostimulating efficacy by increasing yield and improving quality, reducing the harmful effects of water deficit. Tested BSs can be a useful tool for wild rocket farmers, especially under scarce water resources.

Interactive effect of water regime, nitrogen rate and biostimulant application on physiological and biochemical traits of wild rocket

A research was carried out to evaluate the biostimulating effects of Azoxystrobin (Azo+) and a brown seaweed extract (SW+) on wild rocket grown during two crop cycles in pots placed in a cold greenhouse. Two watering regimes were applied (restoring 50% and 100% of crop evapotranspiration, indicated respectively WR50 and WR100) along with three N levels (0, 75 and 150 kg ha−1 of N). The experimental layout was a split-split plot with three replications, arranging water regimes in the main plots, N levels in the plots and biostimulants in the sub-plots. The paper reports the results related to the effects on i) leaf chlorophyll content (Chl), ii) parameters related to gas exchanges including net assimilation (A), transpiration (T), stomatal conductance (gs), internal CO2 concentration (Ci) and intrinsic water use efficiency (WUEi), iii) some enzymes involved in oxidative stress including superoxide dismutase (SOD), peroxidase (POD), ascorbate peroxidase (APX), catalase (CAT). The water deficit led to a drop in A and T, an increase in WUEi and in the antioxidant enzymes content of wild rocket. Chl rised with the N availability increase. The increase in N level caused the rise of A and T in WR100 while it exacerbated the negative effect of water deficit in WR50. Azo+ caused 15.0% increase in A, 13.4% drop in gs and 33.5% rise in WUEi. Additionally, Azo+ increased by 8.7% Chl and by 489%, 112%, 193%, and 336% SOD, POD, APX and CAT, respectively. SW+ improved A (+7.9%), WUEi (+14.9%), Chl (+6.1%), SOD (+395%), POD (+160%), APX (+155%) and CAT (+334%). The increase in antioxidant enzymes after the application of Azo+ and SW+ was greater under water deficit. The wild rocket benefited of Azo+ and SW+ application, which stimulated the biosynthesis of chlorophyll and antioxidant enzymes, demonstrating the potential role in limiting water stress. Therefore, the two biostimulants can represent a useful tool to improve the production of wild rocket and increase the water use efficiency.

Effect of water regime on the dynamics of free ammonia during high solid anaerobic digestion of pig manure

Free ammonia (FAN) inhibition is commonly encountered during high solid anaerobic digestion (HSAD) of pig manure. The performance of HSAD is highly related to its operational water regime; however, little information is available regarding the dynamics of free ammonia with varied water regimes. In this work, four treatments were set with equal amount of water supply but varied addition frequencies, i.e. add once but at different times in treatments T1 and T2, add twice in T3 while it was three times in treatment T4. Results showed that the whole methanogenic process ran smoothly with the average methane gas production rate maintaining at 191.1 LCH4/kgVSadded. Although a higher methane gas production rate of 217.4 LCH4/kgVSadded was achieved in T1, one time water addition triggered a higher ammonia inhibition potential. Cumulative FAN release was 6.03 mgFAN/kgVSadded in T1 while the balance between FAN and ammonia tended to the fraction of FAN. In T4, cumulative FAN of 5.07 mgFAN/kgVSadded was evolved, which was lower than that in T1 but similar to the situation in T2. The lowest FAN was observed in T3, indicating that a moderate frequency of dilution might be conducive to alleviate free ammonia inhibition.

Native and invasive seedling drought-resistance under elevated temperature in common gorse populations

AbstractThe assumption that climatic growing requirements of invasive species are conserved between their native and non-native environment is a key ecological issue in the evaluation of invasion risk. We conducted a growth chamber experiment to compare the effect of water regime and temperature on the growth and mortality of native and invasive populations of common gorse seedlings (Ulex europaeus L.). Seeds were sampled from 20 populations of five areas from both native (continental France and Spain) and non-native areas (New Zealand, Canary and Reunion islands). The seedlings were grown over 36 days in two temperature treatments (ambient and elevated) combined with two water treatments (irrigated or droughted). The elevated temperature (ET) was defined as the highest temperature observed at the niche margin in the different countries. While ET increased seedlings growth, the drought treatment increased mortality rate and limited seedlings growth. Under ET and drought, native populations showed a greater mortality rate (53%) than invasive populations (16%). Invasive seedlings also showed higher above- and belowground development than native ones under these constrained climatic conditions. While phenotypic plasticity did not differ between native and invasive populations, the difference between populations in terms of total dry mass could be related to differences in the climate of origin (precipitation in particular). Assessing the importance of phenotypic changes between populations within invasive species is crucial to identify the margins of their climatic distribution range and to highlight areas where management efforts should be concentrated in order to limit its spread.

Evaluation and genetic variation of lutein content in Chinese common wheat

Selection of lutein-rich genotypes through breeding can enhance the nutritional value of wheat and provide a healthier diet. The present study used high performance liquid chromatography to analyze the lutein content of the Chinese wheat Mini Core Collection of 262 common wheats. In addition, the effects of water regime, accession type, release year, geographical origin, and the correlation of lutein content with various agronomic traits was examined. The lutein content among genotypes varied ten-fold, ranging from 0.87 to 8.90 μg/g. Ten cultivars with an average content more than 5.0 μg/g were identified as sources of the high lutein trait. Lutein content among different environments was significantly correlated and the genotype (G) and environment (E) response showed G > G × E > E with the effect of water level likely to be small. These results also demonstrated that the lutein content of Chinese wheat had not undergone extensive selection during the breeding process and was independent of accession type, plant habit, and grain color. However, lutein content was related to the geographical origin of accessions. Among ten agronomic traits evaluated, only grain related traits were associated with lutein content. These results provided essential information for breeding programs to improve the nutritional quality of wheat by enhancing lutein content.

Effect of water regimes and harvest times on yield and phytochemical accumulation of two ginger species

In South Africa, both Commercial ginger (Zingiber officinale Roscoe) and African ginger (Siphonochilus aethiopicus (Schweinf.) BL Burtt) are significant medicinal plants. This study aimed to determine the effect of water regimes on the two-ginger species' phenolic content, antioxidant properties and yield at various harvest times. During the 2015/2016 and 2016/2017 crop seasons, a field experiment was conducted. The experiment used a randomised complete block design (RCBD) and included two ginger species, four irrigation regimes, and three replicate blocks. Four different levels of soil water availability (20-25%, 40-45%, 60-65%, and 80-85% maximum allowable depletion, MAD) were used. The severely stressed treatment (80-85% MAD) significantly increased total flavonoid and phenolic content and total antioxidant activity in both species, but the biomass yield was lower than the other treatments. The well-watered control (20-25% MAD) resulted in a significant increase in rhizome yield at different harvesting times but resulted in lower total flavonoid and phenolic content and total antioxidant activity for both species. However, the moderately stressed treatment (40-45% MAD) obtained a higher WUE, flavonoid, phenolic and antioxidant content without reducing yield significantly in both species. The results indicated a similar trend in phytochemical constituents for leaves and rhizomes. The species can be harvested seven to eight months after planting under open field conditions. The accumulation of phytochemicals is dependent on water regime, harvesting time, and plant part; growers should consider 40-45% MAD and harvest seven to eight months after planting when growing ginger species to save the scarce resource (water), high phytochemical content and rhizome yield.

Effect of water regime and palm mass on cultivation of green pepper

In this study, we aimed to evaluate the agronomic behavior of green peppers subjected to different water regimes and masses of forage cactus incorporated into sandy soil in a tropical climate. The treatments were organized in a 4 × 4 factorial scheme, with water regimes and forage cactus masses incorporated into the soil in a randomized block design. The results allowed us to observe an isolated significant difference for each factor studied. The water regime RH=100% of the vessel capacity (VC) and mass density of 100 g dm−3 of forage cactus incorporated into the soil positively affected the plant height variables, stem diameter, total chlorophyll, and water potential; specifically, these treatments were superior to soil with water restriction and without the addition of forage palm by 63%, 15%, 61%, and 71%, and 87%, 85%, 81%, and 63%, respectively. The doses of soil conditioner masses containing 0 g dm−3 and 100 g dm−3 of palm in the soil showed the best results for the number of fruits (3.25 and 2.00 fruits), number of commercial fruits (2.0 and 1.5 fruits), and fruit length (88.87 mm and 95.92 mm). Forage cactus mass of 100 g dm−1 of Quartzarenic Neosol and 100% VC irrigation water regime is the most recommended treatment for the protected cultivation of green pepper, as it positively influences productivity and the morphophysiological characteristics of the crop.