Land‐Atmosphere Cascade Fueled the 2020 Siberian Heatwave

1. Tree growth, yield and fruit quality of Jonathan apples cultured in the large size pots were observed under four different conditions of soil moisture, such as“High”80-75%, “Medium”70-70%, “Low”45% and“Very low”30% of water holding capacity. And further observations were made on the morphological charactors of leaves and fruits, apparent photosynthesis, transpiration, and nutrient content of leaves with changing soil moisture.2. Tree growth, especially top growth was markedly inferior with decreasing soil moisture, and yield and fruit size were also proportional to soil moisture.3. Skin color of fruits in the“High”plot was inferior considerably to that of the others, and sugar content of fruits decreased with increasing soil moisture. In the“Very low”plot, fruits had no crispness. From these points, it seems that dessert quality of fruits was most superior in the“Low” plot.4. Daily changes of fruit size and trunkgirth were checked in summer. Both of the fruits and the trunks shrunk during daytime and swelled again at night. The difference of fruit size between day and night became greater with increasing soil moisture, because the number of leaves per fruit increased conspicuously with increasing soil moisture.5. Leaves in the lower soil moisture plot were inferior in area, thickness, cell size and the extent of intercellular spaces, however, they were superior in the thickness of cuticle layer and the density of stomata to those in the higher one. Fruits in the lower soil moisture plot had a thick skin and a firm flesh filled compactly with small cells, which had a thick wall as compared with those in the higher one. There is no significant difference in the number of cells in flesh in each plot.6. In the“Very low”plot, many of the older leaves became yellow and abscised in summer.7. In the“Very low”plot, almost half of the fruits produced corky core owing to boron deficiency, and also, internal breakdown occurred in some fruits after the storage for two months.8. There was no significant difference in the rate of apparent photosynthesis between the“High”and “Medium”plots, but in the lower plots, it decreased apparently with decreasing soil moisture. The rate of transpiration is also proportional to soil moisture.9. As the result of leaf analysis for N, P, K, Ca, Mg and B, the contents of P and B in leaves decreased considerably with decreasing soil moisture.

Effects of different irrigation regimes on soil moisture availability evaluated by CSM-CERES-Maize model under semi-arid condition

Soil moisture governs vegetation growth and distribution, which in turn affects its dynamics through transpiration, interception, root water uptake, and soil structure improvement. Understanding these interactions is vital for effective ecosystem management and sustainable development. This study analyzes the interactions and lag effects between soil moisture at different depths and NDVI on the Mongolian Plateau from 1982–2022 using trend, correlation, and nonlinear Granger causality analyses. The results show that the significant increase in vegetation is accompanied by a notable decrease in soil moisture. Increased vegetation promotes shallow soil moisture retention but accelerates deep soil moisture depletion as drought intensifies, extending the lag time. Concurrently, while soil moisture generally positively affects NDVI, this relationship becomes negatively correlated in deeper layers. Overall, soil moisture had a causal relationship with NDVI in 65.7 to 76.9% of the areas, indicating broad influence by soil moisture. Conversely, vegetation exerted a regulatory effect on soil moisture in 38.9to 66.5% of the regions. As depth increased, bidirectional causality gradually weakened, transitioning to a unidirectional influence of soil moisture on NDVI. In arid regions, NDVI more significantly impacted deep soil moisture, highlighting the need for increased focus on vegetation's effect on water consumption.

Carbon and water cycle dynamics of vegetation are controlled primarily by photosynthesis and stomatal conductance (gs). Our goal is to improve the representation of these key physiological processes within the JULES land surface model, with a particular focus on refining the temperature sensitivity of photosynthesis, impacting modelled carbon, energy and water fluxes. We test (1) an implementation of the Farquhar et al. (1980) photosynthesis scheme and associated plant functional type-dependent photosynthetic temperature response functions, (2) the optimality-based gs scheme from Medlyn et al. (2011), and (3) the Kattge and Knorr (2007) photosynthetic capacity thermal acclimation scheme. New parameters for each model configuration are adopted from recent large observational datasets that synthesise global experimental data. These developments to JULES incorporate current physiological understanding of vegetation behaviour into the model, and enable users to derive direct links between model parameters and on-going measurement campaigns that refine such parameter values. Replacement of the original Collatz et al. (1991) C3 photosynthesis model with the Farquhar scheme results in large changes in GPP for current-day, with ~10 % reduction in seasonal (June–August; JJA and December–February; DJF) mean GPP in tropical forests, and ~20 % increase in the northern high latitude forests in JJA. The optimality-based gs model decreases the latent heat flux for the present-day (~10 %, with an associated increase in sensible heat flux) across regions dominated by needleleaf evergreen forest in the northern hemisphere summer. Thermal acclimation of photosynthesis coupled with the Medlyn gs scheme reduced tropical forest GPP by up to 5 %, and increased GPP in the high northern latitude forests by between 2 to 5 %. Evaluation of simulated carbon and water fluxes by each model configuration against global data products show this latter configuration generates improvements in these key areas. Thermal acclimation of photosynthesis coupled with the Medlyn gs scheme improved modelled carbon fluxes in tropical and high northern latitude forests in JJA, and improved the simulation of evapotranspiration across much of the northern hemisphere in JJA. Having established good model performance for the contemporary period, we force this new version of JULES offline with a future climate scenario corresponding to rising atmospheric greenhouse gases (SSP5 RCP8.5). In particular, these calculations allow understanding of the effects of long-term warming. We find that the impact of thermal acclimation coupled with the optimality-based gs model on simulated fluxes increases latent heat flux (+50 %) by year 2050 compared to the JULES model configuration without acclimation. This new JULES configuration also projects increased GPP across tropical (+10 %) and northern latitude regions (+30 %) by 2050. We conclude that thermal acclimation of photosynthesis with the Farquhar photosynthesis scheme and the new optimality-based gs scheme together improve the simulation of carbon and water fluxes for current-day, and has a large impact on modelled future carbon cycle dynamics in a warming world.

Growth, developmental, and physiological responses of two sweetpotato (Ipomoea batatas L. [Lam]) cultivars to early season soil moisture deficit

The effects of soil moisture variation on the litter decomposition of main tree species Betula platyphylla, Abies nephrolepis and Pinus koraiensis were evaluated in a primary forest of Korean pine (P. koraiensis) in Fenglin National Nature Reserve of the Northeast China, based on the measurements of surface (0-10 cm) soil moisture from 1998 to 2017. The results showed that litter decomposition rates increased with the increase of litter quality. The order of litter decomposition rate was B. platyphylla > A. nephrolepis > P. koraiensis at the same soil moisture. The litter decomposition rates decreased with the decrease of soil moisture. The sensitivity index of litter decomposition rates on soil moisture (M10) were 0.782, 0.789 and 0.827, respectively, for B. platyphylla, A. nephrolepis and P. koraiensis. The initial litter decomposition rate decreased by 21.8%, 21.1% and 17.3% for B. platyphylla, A. nephrolepis and P. koraiensis, respectively, when soil moisture decreased by 10%. The decomposition rates of high-quality litter (high nitrogen content, low carbon to nitrogen ratio, and low lignin content) were more sensitive to the variation of soil moisture. The difference in decomposition rate among different litter types was reduced with the decrease of soil moisture. In the recent 20 years, the average soil moisture presented a significantly decreasing trend, which would inhibit litter decomposition in the primary Korean pine forest. Under the scena-rios of global change, soil moisture would further decrease with the increase of air temperature. It would definitely intensify the inhibitory effect on litter decomposition, and partly offset the enhanced effects of increased air temperature.

Water use and soil moisture depletion by olive trees under different irrigation conditions

Climate change is expected to alter primary production and community composition in alpine ecosystems, but the direction and magnitude of change is debated. Warmer, wetter growing seasons may increase productivity; however, in the absence of additional precipitation, increased temperatures may decrease soil moisture, thereby diminishing any positive effect of warming. Since plant species show individual responses to environmental change, responses may depend on community composition and vary across life form or functional groups. We warmed an alpine plant community at Niwot Ridge, Colorado continuously for four years to test whether warming increases or decreases productivity of life form groups and the whole community. We provided supplemental water to a subset of plots to alleviate the drying effect of warming. We measured annual above-ground productivity and soil temperature and moisture, from which we calculated soil degree days and adequate soil moisture days. Using an information-theoretic approach, we observed that positive productivity responses to warming at the community level occur only when warming is combined with supplemental watering; otherwise we observed decreased productivity. Watering also increased community productivity in the absence of warming. Forbs accounted for the majority of the productivity at the site and drove the contingent community response to warming, while cushions drove the generally positive response to watering and graminoids muted the community response. Warming advanced snowmelt and increased soil degree days, while watering increased adequate soil moisture days. Heated and watered plots had more adequate soil moisture days than heated plots. Overall, measured changes in soil temperature and moisture in response to treatments were consistent with expected productivity responses. We found that available soil moisture largely determines the responses of this forb-dominated alpine community to simulated climate warming.

BackgroundClimate change and increasing demand in non-agricultural sectors profoundly affect the availability and quality of water resources for irrigated agriculture. The FAO AquaCrop simulation model provides a sound theoretical framework to investigate crop yield response to environmental stress. This model has successfully simulated crop growth and yield as influenced by varying soil moisture environments for crops. Integrating crop models that simulate the effects of water on crop yield with targeted experimentation can facilitate the development of irrigation strategies for high yield procurement and improving farm level water management and water use efficiency (WUE) under climatic condition of District Hyderabad, Sindh, Pakistan.ResultsThis study was based on completely randomized block design with three treatments including T1 (30% soil moisture depletion), T2 (50% soil moisture depletion) and T3 (70% soil moisture depletion) with three replicates. In order to determine the crop water requirements under desired treatments, the gypsum blocks were used for computing the daily soil moisture depletion. The result shows that total volume of water applied to crop under T1, T2 and T3 was 9689, 5200 and 2045 m3 ha−1, respectively. As a result, the grain yield under T1, T2 and T3 was 13.2, 12.1 and 14.3 t ha−1, respectively. These results advocate that total yield of crop under T1 and T2 was less as compared to T3. The T3 gave higher yield and WUE compared than other treatments. On the other hand, results revealed that the simulated sunflower yields showed a good agreement with their measured under T3. The simulated grain yield was 15.5 t ha−1, while the measured yield varied from 12.1 to 14.3 t ha−1. This study suggested that WUE under T3 was more as compared to T1 and T2. The results showed that the T3 gave the highest crop yield in relation to WUE and optimize yield of sunflower crop under water scarcity.ConclusionThe Aquacrop model could very well predict crop yield and WUE at T3 under experiential region for sunflower production.

Vegetation distribution along mountain environmental gradient predicts shifts in plant community response to climate change in alpine meadow on the Tibetan Plateau

Variations in quality constituents of green tea leaves in response to drought stress under south Indian condition

Influence of changes in rainfall and soil moisture on trends in flooding

Growth, nicotine and phosphorus content of tobacco, as influenced by soil temperature, soil moisture and soil phosphorus levels, were investigated by growing the flue-cured variety Hicks in a combination of three soil temperature, four soil moisture, and three soil phosphorus treatments.Soil temperature of 22 °C. and soil moisture of 75 per cent of available moisture appeared to be the best for the over-all growth of tobacco. The over-all growth was a little lower at the 30 °C. soil temperature than at the 22 °C. temperature while at the 14 °C temperature it was very poor. Nicotine and phosphorus content in leaf tissue decreased with decreasing soil temperature. A decrease in soil moisture decreased the growth but increased the nicotine content of tobacco. Phosphorus content was influenced little by soil moisture treatments. Low soil moisture treatments were more detrimental to growth of tobacco at the low soil temperature than at the higher ones. Phosphorus produced growth responses at the low soil temperature only. Nicotine content was not influenced by soil phosphorus treatments. Phosphorus applications increased the leaf phosphorus content. At the 14 °C. soil temperature there was an increase in leaf and stalk weight and leaf area with added phosphorus while at the 22° and 30 °C. increases with soil temperature were very small. Stalk weights increased with increasing phosphorus applications at the higher but not at the lower soil moisture levels. The growth was decreased more at the soil temperature of 14 °C. and soil moisture treatments of 25, and near 0 per cent of available moisture than at the soil temperature of 22° and 30 °C. At the low soil moisture phosphorus applications decreased root growth while at the higher soil moisture treatments this phosphorus effect was reversed.

An experiment was conducted in Jamalpur during the Rabi seasons of 2004-2005 and 2005-2006 to investigate the yield and scab infection of potato variety Diamant under different irrigation frequencies and quantities. Three irrigation intervals, 7, 12 and 17 days along with three levels of water quantities equaling 50, 100 and 150% of depleted soil moisture were tested for yield and scab infection of potato tubers. It was observed in 2004-2005 that irrigation interval of 12 days and watering at 100% depletion of soil moisture produced the highest fresh and total yields of 24.64 t/ha and 27.56 t/ha, respectively, whereas irrigation interval of 7 days and watering at 150% of depleted soil moisture produced the lowest fresh and total yields (21.68 t/ha and 25.98 t/ha, respectively). In 2005-2006, irrigation interval of 12 days and watering at 100% depletion of soil moisture produced the fresh and total yields of 26.27 t/ha and 27.41 t/ha, respectively, and were not found statistically different from those obtained under water application of 150% depleted soil moisture and irrigation interval of 12 days. The scab infected tubers were found the highest 4.30 t/ha in 2004-2005 and 2.97 t/ha in 2005-2006 for water application of 150% depleted soil moisture and 7 days irrigation intervals. This indicates that scab disease is more susceptible to frequent and over irrigation. Key Words: Irrigation interval; moisture depletion; scab disease. DOI: 10.3329/bjar.v34i4.5843Bangladesh J. Agril. Res. 34(4) : 683-692, December 2009

Vitamin D deficiency and co-morbidities in COVID-19 patients – A fatal relationship?