Search Results (14)

Various high-throughput screening methods have been developed to explore plant phenotypes, primarily at the organ and whole plant levels. There is a need to develop phenomics methods at the cellular level to narrow down the genotype to phenotype gap. This study used double-resonator piezoelectric cytometry biosensors to capture the dynamic changes in mechanical phenotypes of living cells of two rice species, drought-resistant Lvhan No. 1 and drought-sensitive 6527, under PEG6000 drought stress. In rice cells of Lvhan No. 1 and 6527, mechanomics parameters, including cell-generated surface stress (ΔS) and viscoelastic parameters (G′, G″, G″/G′), were measured and compared under 5–25% PEG6000. Lvhan No. 1 showed larger viscoelastic but smaller surface stress changes with the same concentration of PEG6000. Moreover, Lvhan No. 1 cells showed better wall–plasma membrane–cytoskeleton continuum structure maintaining ability under drought stress, as proven by transient tension stress (ΔS > 0) and linear G′~ΔS, G″~ΔS relations at higher 15–25% PEG6000, but not for 6527 cells. Additionally, two distinct defense and drought resistance mechanisms were identified through dynamic G″/G′ responses: (i) transient hardening followed by softening recovery under weak drought, and (ii) transient softening followed by hardening recovery under strong drought. The abilities of Lvhan No. 1 cells to both recover from transient hardening to softening and to recover from transient softening to hardening are better than those of 6527 cells. Overall, the dynamic mechanomics phenotypic patterns (ΔS, G′, G″, G″/G′, G′~ΔS, G″~ΔS) verified that Lvhan No. 1 has better drought resistance than that of 6527, which is consistent with the field data. Full article

The extreme weather and the deteriorating water environment have exacerbated the crisis of freshwater resource insufficiency. Many studies have shown that salty water could replace freshwater to partly meet the water demand of plants. To study the effects of early-stage drought hardening and late-stage salt stress on tomatoes (Solanum lycopersicum L.), we conducted a 2-year pot experiment. Based on the multi-objective demands of high yield, high quality, and water saving, yield indicators, quality indicators, and a water-saving indicator were selected as evaluation indicators. Three irrigation levels (W1: 85% field capacity (FC), W2: 70% FC, W3: 55% FC) and three salinity levels (S2: 2 g/L, S4: 4 g/L, S6: 6 g/L) were set as nine treatments. In addition, a control treatment (CK: W1, 0 g/L) was added. Each treatment was evaluated and scored by principal component analysis. The results for 2022 and 2023 found the highest scores for CK, W2S2, W3S2 and CK, W2S4, W2S2, respectively. Based on response surface methodology, we constructed composite models of multi-objective demands, whose results indicated that 66–72% FC and 2 g/L salinity were considered the appropriate water–salt combinations for practical production. This paper will be beneficial for maintaining high yield and high quality in tomato production using salty water irrigation. Full article

The spatial extent of semi-arid hot regions is forecasted to grow through the twenty-first century, complicating restoration and reforestation plans. In arid and semi-arid climates, seedlings are more susceptible to transplant shock due to lower soil moisture throughout the year. Determining strategies to reduce seedling stress and improve survival post-planting will be paramount to continued reforestation efforts in a changing climate. We quantified seedling physiological, morphological, and field performance (mortality and growth) response for five species native to the semi-arid region of South Texas (Erythrina herbacea L., Celtis pallida Torr., Fraxinus berlandieriana DC, Malpighia glabra L., and Citharexylum berlandieri B.L Rob) to an antitranspirant (abscisic acid), drought, and elevated CO₂. We examined post-treatment seedling gas exchange, non-structural carbohydrates, osmolality, root structure, and stomatal density and evaluated mortality and growth rate on a sample of the treatment population. For elevated CO₂ and drought hardening treatments, seedling gas exchange, solute content, specific root length, and stomatal density varied by species, while abscisic acid strongly reduced transpiration and stomatal conductance in all species. However, these physiological and morphological differences did not translate to reduced mortality or improved growth rate due to high herbivory and above-normal precipitation after planting precluding seedlings from stress. We conclude that the simpler antitranspirant approach, rather than the more logistically challenging eCO₂, has the potential to reduce drought-related transplant shock but requires more widespread testing. Full article

Drought hardening could promote the development of plant roots, potentially improving the resistance of crops to other adversities. To investigate the response and resistance of physiological and growth characteristics induced by drought hardening to salt stress in the later stages, a greenhouse experiment was carried out from 2021 to 2022 with one blank control treatment and twelve treatments that comprised combinations of four irrigation regimes (W1 = 85%, W2 = 70%, W3 = 55%, and W4 = 40% of the field capacity) and three irrigation water salinity levels (S2, S4, and S6, referring to 2 g, 4 g, and 6 g of sodium chloride added to 1000 mL of tap water, respectively). The results show that saline water irrigation introduced a large amount of salt into the soil, resulting in the deterioration of tomato growth, physiology, yield, and water use efficiency (WUE), but had a positive, significant effect on fruit quality. When the irrigation water salinity was 2 g L⁻¹, the W2 treatment could reduce soil salt accumulation, even at the end of the maturation stage; consequently, enhancing the increments in plant height and leaf area index during the whole growing stage. The physiological activity of tomato plants under the W2 and W3 treatments showed a promoting effect. Correspondingly, the maximum values of the fruit quality of tomato plants irrigated with the same saline water were all obtained with the W2 or W3 treatment. However, the yield and WUE of the W3 treatment were lower than that of the W2 treatment, which was the highest among the same saline water irrigation treatments, consistent with the reflection of the changing trend of the ratio of fresh weight to dry weight. Overall, drought hardening can be considered an economically viable approach to mitigate the hazards of saline water irrigation, and the W2S2 combination is recommended for tomato production due to the maximum values of yield and WUE with a higher fruit quality among the twelve saline water irrigation treatments. Full article

Heat and drought stresses are increasingly relevant topics in the context of climate change, particularly in the Alps, which are warming faster than the global average. Previously, we have shown that alpine plants, including Primula minima, can be gradually heat hardened under field conditions in situ to achieve maximum tolerance within a week. Here, we investigated the antioxidant mechanisms of P. minima leaves that had been heat hardened (H) without or with (H+D) additional drought stress. Lower free-radical scavenging and ascorbate concentrations were found in H and H+D leaves, while concentrations of glutathione disulphide (GSSG) were higher under both treatments without any change in glutathione (GSH) and little change in glutathione reductase activity. In contrast, ascorbate peroxidase activity in H leaves was increased, and H+D leaves had >two-fold higher catalase, ascorbate peroxidase and glucose-6-phosphate dehydrogenase activities compared with the control. In addition, the glutathione reductase activity was higher in H+D compared with H leaves. Our results highlight that the stress load from heat acclimation to maximum tolerance is associated with a weakened low-molecular-weight antioxidant defence, which may be compensated for by an increased activity of antioxidant enzymes, particularly under drought conditions. Full article

Endocarp development in olive trees includes three periods: growth (Period I), massive sclerification (Period II) and maximum hardening (Period III). The two first are strongly related to yield and irrigation management. Period I was reported to coincide with mesocarp cell division and thus with final fruit size. Period II was considered to be the most drought-resistant phenological stage. However, little is known in olive trees about the length of these periods and their capacity for predicting fruit size at harvest. The aim of this work was to evaluate the length of both periods in different cultivars and different location of full irrigated orchards. We also aimed to study the fruit feature impact on harvest at the end of Period I. Data from full irrigated olive orchards of cv Cornicabra, Arbequina and Manzanilla in two different locations (Ciudad Real, Central Spain, and Seville, South Spain) were used. The pattern of pit-breaking pressure throughout the season was measured with fruit samples for several years (2006 to 2022). These data and climatic data were used to compare different estimation methods for the length of Period I and II of endocarp development. Then, fruit volume and dry weight at the end of Period I were used to estimate fruit features at harvest. Results suggest that the Period I length was less temperature- and cultivar-dependent than expected. The duration of this period was almost constant at around 49 days after full bloom. Thermal time was negatively correlated with fruit size at the end of Period I. On the contrary, a lineal thermal model presented the lowest variability when estimating the Period II length, which was also affected by the cultivar. The best fit between fruit dry weight and volume at Period I vs. harvest was unique for oil cultivars (Cornicabra and Arbequina), while cv Manzanilla presented a different relationship. A temperature increase in the future would not affect the Period I length but would reduce the fruit size at the end of this period and at harvest. Full article

Very limited information is available on the drought tolerance of European beech and silver fir in mixed cultivation, both for mature forests and natural regeneration. Particularly, little information is available regarding the significance on memory effects of drought exposure. Therefore, drought memory was analyzed in seedlings of these species grown in mixed cultivation in the present study. The results showed that previous-year drought hardening mediated enhanced biomass accumulation of beech leaves and root in the subsequent year, but did not impact fir growth. Total carbon (C) content was decreased by drought hardening in both the leaves and roots of beech and previous-year needles and roots of fir, in beech probably as a consequence of increased growth. Previous-year drought hardening had no significant effect on relative water contents, total nitrogen (N), or soluble protein contents in leaves and roots of beech and fir, but resulted in decreased total amino acid contents of beech leaves and fir needles. It further reduced structural N in current-year fir needles and decreased C/N ratios in roots of both beech and silver fir seedlings. Generally, the number of interspecific neighbors had no considerable effect on biomass or total C or N contents, as well as N partitioning in leaves and roots of beech and fir seedlings. The present study highlights that drought hardening induces memory effects in European beech and silver fir seedlings in their mixture in the subsequent year of growth, but these memory effects are stronger in beech than in fir. Full article

To alleviate the enhanced frequency, duration, and intensity of drought as a consequence of global warming, admixing drought-sensitive European beech (Fagus sylvatica L.) with deep rooting silver fir (Abies alba Mill.) has been proposed. However, information on the performance of the admixtures of seedlings of these tree species at limited water availability has so far not been reported. In the present study, we investigated the significance of water deprivation in mixtures of beech and fir seedlings on the foliar relative water content (RWC), δ¹³C signature, total C and N contents, and C:N ratios of both species in a drought-rewetting cycle. Surprisingly, moderate drought triggered increased RWC in beech leaves and current year fir needles indicating drought hardening. The enhanced foliar RWC was preserved after rewatering in beech leaves, but not in current year fir needles. Drought did not significantly affect δ¹³C abundance in beech leaves, but enhanced the δ¹³C abundance (less negative values) in current and one-year old fir needles, indicating stomatal control in fir needles but not in beech leaves upon moderate drought. Total C contents of beech leaves were significantly increased upon drought and rewatering, but remained constant in fir needles. Foliar total N increased in both species upon drought and decreased upon rewatering. Accordingly, C:N ratios decreased in response to drought and recovered after rewatering. These results suggest that drought hardening may be achieved at least partially via osmotic adjustment by different compatible solutes in beech leaves and fir needles. No apparent effects of the number of neighbours were observed, although more fir neighbours tended to increase the RWC and total C contents of beech leaves. These results indicate that drought hardening in mixtures of beech and fir seedlings is largely independent of the number of interspecies neighbours. Full article

Harsh environmental conditions derived from current climate change trends are among the main challenges for agricultural production worldwide. In the Mediterranean climatic region of central Chile, sudden occurrence of spring cold temperatures in combination with water shortage for irrigation (drought) constitutes a major limitation to highbush blueberry (Vaccinium corymbosum) plantations, as flowering and fruiting stages are highly sensitive. Hardening crops may be achievable by boosting beneficial interactions of plants with microorganisms. Inoculation with symbiotic fungi isolated from plants adapted to extreme environments could be a good strategy, if they are able to maintain functional roles with non-original hosts. Here, we evaluated the effect of two Antarctic fungal endophytes (AFE), Penicillium rubens and P. bialowienzense, on the tolerance of V. corymbosum plants to cold events in combination with drought under controlled conditions. Inoculated and uninoculated plants were exposed for a month to one event of a cold temperature (2 °C/8 h) per week with or without drought and were evaluated in physiological, biochemical, and molecular variables. A complementary set of plants was kept under the same environmental conditions for two additional months to evaluate survival as well as fruit weight and size. There was an overall positive effect of AFE on plant performance in both environmental conditions. Endophyte-inoculated plants exhibited higher gene expression of the Late Embryogenesis Abundant protein (LEA1), higher photochemical efficiency (Fv/Fm), and low oxidative stress (TBARS) than uninoculated counterparts. On the other hand, plant survival was positively affected by the presence of fungal endophytes. Similarly, fruit diameter and fruit fresh weight were improved by fungal inoculation, being this difference higher under well-watered condition. Inoculating plants with fungal endophytes isolated from extreme environments represents a promising alternative for hardening crops. This is especially relevant nowadays since agriculture is confronting great environmental uncertainties and difficulties which could became worse in the near future due to climate change. Full article

A previous study revealed low survival rates for Japanese larch (Larix kaempferi) summer-planted seedlings grown in Hiko-V-120 containers. This study examines nursery practices that could potentially prevent deterioration of the seedling water balance after planting to improve the survival rate of this species, which has a low drought tolerance. During summer planting, we tested (1) drought hardening or high-potassium fertilization for two months before planting, (2) antitranspirant or topping treatment at planting, and (3) the use of the JFA-150 container with a larger capacity and lower growing density than the Hiko-V-120 container. Drought hardening increased seedling drought tolerance because of the low leaf:root ratio, due to lower leaf mass production, resulting in increased survival from 74% to 93% in Hiko-V-120 containers. When JFA-150 containers were used, the leaf:root ratio was lower because of higher root mass, resulting in an increase in survival to 87%, with the highest survival of 97% when combined with drought hardening. The application of antitranspirant increased survival to over 90%, whereas topping did not, probably because of severer competition from weeds. High-potassium fertilization did not affect seedling traits or survival. For better survival of summer-planted container-grown Japanese larch seedlings, it is recommended that they be grown in containers providing sufficient cell volume and density for root growth while the seedlings are in the nursery and that irrigation be withheld for two months before planting. In addition, to obtain higher survival, an antitranspirant can be applied at planting at a cost. Full article

Water shortage is a major environmental stress that destructively impacts maize production, particularly in arid regions. Therefore, improving irrigation management and increasing productivity per unit of water applied are needed, especially under the rising temperature and precipitation fluctuations induced by climate change. Laboratory and field trials were carried out in the present study, which were aimed at assessing the possibility of promoting maize germination, growth, grain yield and crop water productivity (CWP) using seed priming under different irrigation regimes. Two seed priming treatments, i.e., hydro-priming and hardening versus unprimed seeds, were applied under four irrigation regimes, i.e., 120, 100, 80 and 60% of estimated crop evapotranspiration (ETc). The obtained results indicated that increasing irrigation water from 100% up to 120% ETc did not significantly increase grain yield or contributing traits, while it decreased CWP. Deficit irrigation of 80 and 60% ETc gradually decreased grain yield and all attributed traits. Seed priming significantly ameliorated seedlings’ vigor as indicated by earlier germination, higher germination percentage, longer roots and shoots, and heavier fresh and dry weight than unprimed seeds with the superiority of hardening treatment. Additionally, under field conditions, seed priming significantly increased grain yield, yield contributing traits and CWP compared with unprimed treatment. Interestingly, the results reflect the role of seed priming, particularly hardening, in mitigating negative impacts of drought stress and enhancing maize growth, grain yield and attributed traits as well as CWP under deficit irrigation conditions. This was demonstrated by a significant increase in grain yield and CWP under moderate drought and severe drought conditions compared with unprimed treatment. These results highlight that efficient irrigation management and seed priming can increase maize yield and water productivity in arid environments. Full article

Climate models in Japan predict that the annual mean air temperature and number of consecutive dry days will increase in the future, leading to high seedling mortality rates. Maintaining high survival rates of Cryptomeria japonica seedlings, a commercially important tree species, is therefore, important in terms of appropriate forest management under climate change. Although drought hardening, in which seedlings are acclimated to dry conditions in the nursery prior to planting, contributes to increased survival under drought conditions, little is known about the effective irrigation frequency of drought hardening in C. japonica seedlings. In this study, we therefore, examine the effectiveness of different drought-hardening treatments in C. japonica. We first clarify the effects on physiological and morphological traits by comparing three drought-hardening treatments [control (C): Irrigation once daily; mild (M): irrigation once every three days; and severe (S): irrigation once every five days] for one month. Next, to confirm the effects during consecutive dry treatment, we stopped irrigation for 13 days and once again compared the physiological traits between the three drought-hardening treatments. Drought hardening reduced whole-plant transpiration (E_whole), resulting in conserved water use, and this tendency was particularly evident under the S treatment. Moreover, during consecutive dry treatment, the E_whole, proportions of non-embolized xylem, and cambium status of basal stem regions were maintained for the longest duration under the S treatment, followed by the M treatment. Our findings suggest that the efficiency of drought hardening increased with drought severity. Furthermore, one month of drought hardening contributed to both water conservation and the maintenance of cell differentiation under consecutive dry treatment, likely increasing the tolerance and survival of C. japonica seedlings under prolonged drought. Full article

Potato is an important food crop and its production is susceptible to drought. Drought stress in crop growth is usually multiple- or long-term. In this study, the drought tolerant potato landrace Jancko Sisu Yari was treated with drought stress, rehydration and re-dehydration, and RNA-seq was applied to analyze the characteristics of gene regulation during these treatments. The results showed that drought-responsive genes mainly involved photosynthesis, signal transduction, lipid metabolism, sugar metabolism, wax synthesis, cell wall regulation, osmotic adjustment. Potato also can be recovered well in the re-emergence of water through gene regulation. The recovery of rehydration mainly related to patatin, lipid metabolism, sugar metabolism, flavonoids metabolism and detoxification besides the reverse expression of the most of drought-responsive genes. The previous drought stress can produce a positive responsive ability to the subsequent drought by drought hardening. Drought hardening was not only reflected in the drought-responsive genes related to the modified structure and cell components, but also in the hardening of gene expression or the “memory” of drought-responsive genes. Abundant genes involved photosynthesis, signal transduction, sugar metabolism, protease and protease inhibitors, flavonoids metabolism, transporters and transcription factors were subject to drought hardening or memorized drought in potato. Full article

Coastal communities exist on the front lines of diverse natural hazards and the growing impacts of climate change. While traditional strategies for dealing with coastal hazards have often involved the hardening or armoring of shorelines, more recent research and practice have demonstrated the value and cost-effectiveness of “living shorelines” and other ecosystem-based strategies for coastal protection. To explore potential relationships among geographic exposure (waterfront vs. inland), shoreline condition (armored vs. natural), and hazard concerns, we surveyed 583 waterfront and inland residents in the northern Gulf of Mexico. We found that overall concern for coastal hazards was similar across waterfront and inland residents, as well as among residents with both armored and natural shorelines. However, concern for specific hazards differed across these groups. Waterfront residents were significantly more concerned about major hurricanes and erosion than inland residents. Conversely, inland residents were more concerned with drought and flooding than waterfront residents. Among waterfront residents, specific hazard concerns were similar between residents with natural and armored shorelines with two key exceptions. Residents with armored shorelines reported higher concern for erosion and sea level rise than residents with natural shorelines. Our results suggest that armored shorelines do not necessarily alleviate concerns about coastal hazards. In the context of balancing social and ecological objectives in addressing coastal hazards or adapting to climate change, understanding the perceptions and behaviors of coastal residents is essential for conserving and protecting coastal ecosystems along residential shorelines. Full article