Search Results (26)

Peanut (Arachis hypogaea L.) is a rainfed crop grown in both tropical and subtropical agro-climatic regions of the world where drought causes around 20% yield losses per year. In the United States, annual losses caused by drought are around $50 million. The objective of this research was to (1) identify genetic variation for the normalized difference vegetation index (NDVI), canopy temperature depression (CTD), relative chlorophyll content by SPAD reading (SCMR), CO₂ assimilation rate, and wilting among recombinant inbred lines (RILs) derived from two diverse parents N08086olJCT and ICGV 86015, to (2) determine if the physiological traits can be used for expediting selection for drought tolerance, and (3) experimental validation to identify lines with improved yield under water-limited conditions. Initially, 337 lines were phenotyped under rainfed production and a selected subset of 52 RILs were tested under rainout shelters, where drought was imposed for eight weeks during the midseason (July and August). We found that under induced drought, pod yield was negatively correlated with wilting and CTD, i.e., cooler canopy and high yield correlated positively with the NDVI and SPAD. These traits could be used to select genotypes with high yields under drought stress. RILs #73, #56, #60, and #31 performed better in terms of yield under both irrigated and drought conditions compared to check varieties Bailey, a popular high-yielding commercial cultivar, and GP-NC WS 17, a drought-tolerant germplasm. Full article

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. Full article

In the context of climate change, future patterns of precipitation are expected to increase the intensity and frequency of drought and flooding stress. This is also likely to result in more frequent flooding–drought alternation events. Drought and flooding stress can have negative effects on tree morphology, physiology, and biochemistry, which can potentially pose long-term threats to tree survival and further disrupt the stability of forest ecosystems. However, it remains unclear how trees would cope with these stressors and their alternations through growth and physiology responses. Potted seedlings of C. camphora were grown under a rainout shelter in the field with four water treatments for 40 days: well-watered (WW), drought stress (DS), flooding stress (FS) and flooding–drought alternation (FDF). Growth, leaf gas exchange, water potential, and biochemical traits were measured. Results show different seedling growth patterns under drought and flooding stress. Drought increased the root-to-shoot ratio (+25%) but flooding favored leaf growth (+33%). Decreases in photosynthesis under drought and flooding were mainly related to stomatal limitations, accompanied by abscisic acid accumulation under drought but not under flooding. Drought reduced water potential, and flooding–drought alternation only decreased water potential in its drought phase. Flooding treatment had no effect on water potential. Drought treatment increased the proline concentrations (+74%) and carbon isotopic composition (+3.7%), but all treatments had no effect on the concentrations of elements in leaves. Drought stress led to carbon depletion in both stem and root, whereas flooding stress primarily induced carbon depletion in the root. Flooding–drought alternation was accompanied by complex physiological responses, including physiological recovery when the stress (flood, drought) was relieved. Our results have shown the different effects of drought and flooding on the growth and physiology of C. camphora seedlings, emphasizing the need to consider specific water stress conditions in future studies and providing a theoretical basis for better management of this tree species in urban areas under variable rainfall patterns. Full article

To investigate the different responses of crops to drought stress under field conditions of Central European Climate for selected crop rotations, a field experiment was conducted at a test site in the Czech Republic from 2014 to 2021. Depending on the crop, rainout shelters were placed in late spring and early summer to study the effects of drought in the final stages of crop development. Due to these rainout shelters and the associated lower water availability for the crops during the summer, a reduction in leaf area index, biomass and yield was observed. For example, a yield decrease of more than 30% was observed for spring barley, winter rape and winter wheat compared to conditions without rainout shelters. The reduction was 25% and 18% for winter rye and silage maize, respectively, under rainout shelters. Soil moisture played a significant role in yield, where a predictive model based on monthly soil moisture explained up to 79% (winter rape) of the yield variance. Full article

Canola plants suffer severe crop yield and oil content reductions when exposed to water-deficit conditions, especially during the reproductive stages of plant development. There is a pressing need to develop canola cultivars that can perform better under increased water-deficit conditions with changing weather patterns. In this study, we analysed genetic determinants for the main effects of quantitative trait loci (QTL), (Q), and the interaction effects of QTL and Environment (QE) underlying seed yield and related traits utilising 223 doubled haploid (DH) lines of canola in well-watered and water-deficit conditions under a rainout shelter. Moderate water-deficit at the pre-flowering stage reduced the seed yield to 40.8%. Multi-environmental QTL analysis revealed 23 genomic regions associated with days to flower (DTF), plant height (PH) and seed yield (SY) under well-watered and water-deficit conditions. Three seed yield QTL for main effects were identified on chromosomes A09, C03, and C09, while two were related to QE interactions on A02 and C09. Two QTL regions were co-localised to similar genomic regions for flowering time and seed yield (A09) and the second for plant height and chlorophyll content. The A09 QTL was co-located with a previously mapped QTL for carbon isotope discrimination (Δ¹³C) that showed a positive relationship with seed yield in the same population. Opposite allelic effects for plasticity in seed yield were identified due to QE interactions in response to water stress on chromosomes A02 and C09. Our results showed that QTL’s allelic effects for DTF, PH, and SY and their correlation with Δ¹³C are stable across environments (field conditions, previous study) and contrasting water regimes (this study). The QTL and DH lines that showed high yield under well-watered and water-deficit conditions could be used to manipulate water-use efficiency for breeding improved canola cultivars. Full article

The root system in plants absorbs water and minerals. However, the relationship among root size, yield, and water use efficiency (WUE) is controversial. Two pot experiments were conducted to explore these relationships by using two maize varieties with contrasting root sizes and reducing the root–shoot ratio (R/S) through root pruning to eliminate genotypic effects. Maize plants were grown in an open rainout shelter under both water-sufficient and deficient conditions. Yield-related parameters, root hydraulic conductivity (Lpr), and WUE were determined. The results showed that the small root variety (XY) has a higher yield and WUE compared to large root variety (QL) under both soil moisture conditions, likely related to the higher Lpr of XY. XY also had a higher leaf water potential than QL under drought stress, indicating that small root system could provide enough water to the shoot. Further pot experiment showed that both small and large root pruning on QL (cut off about 1/5 roots, RP1; and cut off about 1/3 roots, RP2, respectively) improved WUE and Lpr, and the RP1 yield increased by 12.9% compared to the control under well-watered conditions. Root pruning decreased transpiration and increased photosynthesis. Thus, this study reveals that it is possible to increase water absorption, yield, and WUE by reducing R/S in modern maize varieties, which may be important for the future breeding of new cultivars suitable for arid regions. Full article

Drought stress often occurs concurrently with heat stress, yet the interacting effect of high vapor pressure deficit (VPD) and soil drying on the physiology of potato plants remains poorly understood. This study aimed to investigate the physiological and growth responses of potatoes to progressive soil drying under varied VPDs. Potato plants were grown either in four separate climate-controlled greenhouse cells with different VPD levels (viz., 0.70, 1.06, 1.40, and 2.12 kPa, respectively) or under a rainout shelter in the field. The VPD of each greenhouse cell was caused by two air temperature levels (23 and 30 °C) combined with two relative humidity levels (50 and 70%), and the VPD of the field was natural conditions. Irrigation treatments were commenced three or four weeks after planting in greenhouse cells or fields, respectively. The results indicated that soil water deficits limited leaf gas exchange and shoot dry matter (DM_shoot) of plants while increasing the concentration of abscisic acid (ABA) in the leaf and xylem, as well as water use efficiency (WUE) across all VPD levels. High VPD decreased stomatal conductance (g_s) but increased transpiration rate (T_r). High VPD increased the threshold of soil water for T_r began to decrease, while the soil water threshold for g_s depended on temperature due to the varied ABA response to temperature. High VPD decreased leaf water potential, leaf area, and DM_shoot, which exacerbated the inhibition of soil drying to plant growth. Across the well-watered plants in both experiments, negative linear relationships of g_s and WUE to VPD and positive linear relations between T_r and VPD were found. The results provide some novel information for developing mechanistic models simulating crop WUE and improving irrigation scheduling in future arid climates. Full article

A combining-ability analysis is key to select desirable parents and progenies with enhanced response to selection under water-limited environments. The objective of this study was to determine combining ability for agronomic and physiological traits among distantly related drought-tolerant bread wheat (Triticum aestivum L.) genotypes under well-watered (WW) and terminal-drought (TD) conditions to determine their genetic merit for breeding. Ten heat- and drought-tolerant wheat genotypes were crossed in a half-diallel mating design to generate 45 F₁s, which were evaluated under WW and TD moisture regimes in rainout shelter (RS) and greenhouse (GH) environments. The following agronomic traits were assessed: days to 50% maturity (DTM), plant height (PH), spike length (SL), number of productive tillers (TN), spikelets number per spike (SPS), number of grains per spike (GPS), grain yield (GY) and thousand-kernel weight (TKW); and physiological traits (stomatal conductance (SC) and chlorophyll content index (CCI)). Variances attributable to general combining ability (GCA) and specific combining ability (SCA) were significant (p < 0.05) for GY, DTM, PH, SL, SPS, GPS, TKW and CCI. The parental genotypes LM72, LM81 and LM95 with positive and significant GCA effects on GY were selected to make crosses to develop high-yielding wheat genotypes for water-limited environments. Crosses LM71 × LM02, LM71 × LM81, LM82 × LM02, LM82 × LM81, LM22 × LM100, LM22 × LM81 and LM95 × LM22 were selected with positive and significant SCA effects for GY. The selected parents and crosses are valuable genetic resources for breeding and genetic advancement. Full article

Effective irrigation strategies are of great significance for improving crop yields. There is an increasing concern that short-season corn hybrids are gradually being encouraged to plant in the North China Plain (NCP) with the development of mechanized grain harvesting, but the photosynthetic characteristics and productivity of short-season hybrids are not well documented. The objective of the study was to investigate the effects of different irrigation treatments on photosynthetic characteristics, dry matter accumulation (DMA) and photo-assimilate translocation (PAT/PT), grain yield (GY) and water productivity (WP) of two corn hybrids differing in maturity. In the experiment plots under the rainout shelter facility, short-season hybrid Denghai518 (DH518) and medium- and full-season hybrid Denghai605 (DH605) were grown under three irrigation levels (severe water stress, T1; mild water stress, T2; and non-stress, T3) by two irrigation methods (flood irrigation, FI; surface drip irrigation, SDI) in 2020 and 2021. The results indicated that non-stomatal limitation (NSL) was the main factor leading to the reduction in photosynthesis during the reproductive stage. Severe water stress significantly decreased net photosynthetic rate (P_n) and chlorophyll soil-plant analysis development (SPAD) value, resulting in lower DMA and GY. The contribution rate of vegetative organ photosynthate before flowering (CRP) decreased with the irrigation levels increasing. DMA, GY and WP of SDI increased by 16.23%, 21.49% and 51.31%, respectively, compared to FI. The yields of DH518 were 7.22% lower than those of DH605. The WP penalty for DH605 was attributed to a relatively larger ET. It suggested that applying the optimum irrigation level (T3) under SDI could increase DMA, GY and WP of summer corn in the NCP. Full article

Extreme climate events such as heat waves, drought, and heavy rainfall are occurring more frequently and are more intense due to ongoing climate change. This study evaluated the early growth performance of one-year-old Larix kaempferi (Lamb.) Carr. seedlings under open-field extreme climate conditions including experimental warming and different precipitation regimes. We recorded the survival rate, root collar diameter, height, biomass, shoot-to-root ratio, and seedling quality index using nine treatments (three temperature levels, i.e., control, warming by 3 °C and by 6 °C, × three precipitation levels, i.e., control, drought, and heavy rainfall) in July and August 2020. The survival rate of seedlings did not differ between treatments, showing high values exceeding 94% across treatments. The measured shoot height was largest under warming by 3 °C and high rainfall, indicating that moderate warming increased seedling height growth in a moist environment. Heavy rainfall decreased stem volume by 21% and 25% under control and warming by 6 °C treatments, respectively. However, drought manipulation using rain-out shelters did not decrease the growth performance. Overall, extreme climate events did not affect the survival rate, biomass, shoot-to-root ratio, and seedling quality index of L. kaempferi. We thus conclude that, regarding growth responses, L. kaempferi seedlings may be resistant to short-term extreme warming and drought events during summer. Full article

Undersowing catch crops (CCs) in cereals provides many environmental benefits and potentially contributes to building agricultural resilience to climate change. The increasing soil water deficit due to global warming is becoming a challenge for the sustainability of Central European agriculture. Some of the multiple functions of CCs may be altered under water shortage. Two pot experiments were conducted in Poland to assess the effect of water deficit on N, P, K, and Mg accumulated in post-harvest residues left by spring barley undersown with Italian ryegrass or red clover, and in the soil under these crops. In both experiments, barley grown alone provided a reference, and two levels of water supply were adopted: higher (sufficient for barley) and lower (reduced by 50%). Under water deficit, CCs undersown in spring barley maintained their function of capturing and storing nutrients. Post-harvest residues of barley undersown with CC and stressed with water shortage accumulated the same or higher amounts of N, P, K, and Mg than residues of barley grown alone under sufficient water supply. Soil nutrient contents were negatively correlated with crop biomass. Further research with other CC species and studies based on field experiments under rainout shelters are recommended. Full article

We investigated seasonal water use, growth and acceptable root-zone water depletion levels to develop tools for the more precise irrigation of two Southeast U.S. landscape species in a monsoonal climate—Magnolia grandiflora and Viburnum odoratissimum. The study was conducted under a rainout shelter consisting of two concurrent studies. One, weighing lysimeter readings of quantified water use (ET_A) at different levels of irrigation frequency that dried the root zone to different allowable depletion levels (ADL). Two, planting the same species and sizes inground and irrigating them to the same ADLs to assess the effect of root-zone water depletion on growth. The projected crown area (PCA) and crown volume were concurrently measured every three weeks in both studies as well as reference evapotranspiration (ETo). Plant factor values were calculated from the ratio of ET_A (normalized to depth units by PCA) to ETo. The two species had different tolerances for irrigation frequency depending on the season: peak magnolia canopy growth was mid-spring to mid-summer, while peak viburnum canopy growth was summer. Canopy growth for both species was most sensitive to greater ADL-water stress during the peak growth stages of both species. For urban landscape irrigation, these data suggest that 60–75% of available water in magnolia and viburnum root zones can be depleted before irrigation and that they can be irrigated at a plant factor (PF) value of 0.6 of ETo. For landscape situations with high expectations, such as during establishment and especially during peak growth, a wetter water budget that minimizes water stress would be more appropriate: 30–45% ADL and PF values of 0.7–0.8. The results of this study are aimed at water managers and landscape architects and designers in a humid climate who need to account for water demand in planning scenarios. Full article

The yield and fruit quality parameters of tomatoes are influenced by environmental conditions, and cultivation systems play an important role in improving quality, apart from breeding. We examined five breeding lines and one cultivar in five cultivation systems for yield and fruit quality parameters. The cultivation systems include a single-glazed greenhouse with and without supplementary LED interlighting; a double-glazed greenhouse with and without supplementary LED interlighting; and an organic cultivation system on the field with a rainout shelter. Plants and fruits grown in the double glazing system showed significantly lower values for plant height, yield, DM, TSS, fructose, glucose, antioxidant capacity (DPPH, TEAC), TPC, calcium, phosphorus, and manganese content than in the single-glazed greenhouse, which can be explained by the lower light transmittance. However, it could be seen that the additional LED interlighting could lower the negative effect on yield and quality traits due to double glazing. Full article

Soybean grain yield has regularly been impaired by drought periods, and the future climatic scenarios for soybean production might drastically impact yields worldwide. In this context, the knowledge of soybean yield is extremely important to subsidize government and corporative decisions over technical issues. This paper aimed to predict grain yield in soybean crop grown under different levels of water availability using reflectance spectroscopy and partial least square regression (PLSR). Field experiments were undertaken at Embrapa Soja (Brazilian Agricultural Research Corporation) in the 2016/2017, 2017/2018 and 2018/2019 cropping seasons. The data collected were analyzed following a split plot model in a randomized complete block design, with four blocks. The following water conditions were distributed in the field plots: irrigated (IRR), non-irrigated (NIRR) and water deficit induced at the vegetative (WDV) and reproductive stages (WDR) using rainout shelters. Soybean genotypes with different responses to water deficit were distributed in the subplots. Soil moisture and weather data were monitored daily. A total of 7216 leaf reflectance (from 400 to 2500 nm, measured by the FieldSpec 3 Jr spectroradiometer) was collected at 24 days in the three cropping seasons. The PLSR (p ≤ 0.05) was performed to predict soybean grain yield by its leaf-based reflectance spectroscopy. The results demonstrated the highest accuracy in soybean grain yield prediction at the R5 phenological stage, corresponding to the period when grains are being formed (R² ranging from 0.731 to 0.924 and the RMSE from 334 to 403 kg ha⁻¹—7.77 to 11.33%). Analyzing the three cropping seasons into a single PLSR model at R5 stage, R² equal to 0.775, 0.730 and 0.688 were obtained at the calibration, cross-validation and external validation stages, with RMSE lower than 634 kg ha⁻¹ (13.34%). The PLSR demonstrated higher accuracy in plants submitted to water deficit both at the vegetative and reproductive periods in comparison to plants under natural rainfall or irrigation. Full article

Most nitrogen (N) in organic fertilizers must be mineralized to become available to plants, a process in which microorganisms play crucial roles. Droughts may impact microorganisms associated with the N cycle, negatively affecting N mineralization and plant N supply. The effects of drought on N-related processes may further be shaped by the farming system. We buried ¹⁵N-enriched plant material and reduced precipitation in conventionally and organically (biodynamically) managed wheat fields. On two sampling dates, we evaluated the soil water content, plant parameters and the plants’ ¹⁵N isotope signature. We intended to study the microbial communities associated with the N cycle to link potential treatment effects on plant N provisioning with characteristics of the underlying microbial community. However, floods impaired the experiment after the first sampling date, and the molecular work on the microbial communities was not performed. Focusing on the pre-flooding sampling date, our data suggested that processes associated with N transformation are sensitive to drought, but the role of the farming system needs further investigation. Since the underlying research question, the set-up and the lessons learned from this study may guide future experiments, we presented improvements to the set-up and provided ideas for additional analyses, hoping to promote research on this topic. Full article