Minimum Soil Temperature Research Articles

Mulching effects on water storage in soil and its depletion by alfalfa in the Loess Plateau of northwestern China

In the dryland region of the Loess Plateau of northern China, alfalfa (Medicago sativa L.) is widely grown for animal feed to develop livestock operations, while also reducing soil erosion and improving soil fertility/quality. A field experiment was carried out on a sandy loam soil from April 2007 to October 2012 to evaluate the processes of soil desiccation in the 500cm soil profiles, and the effects of mulch management on soil water content and temperature in the upper soil layer (5–15cm), water use efficiency (WUE) and forage dry matter yield (DMY) of alfalfa in rainfed pasture land. Three treatments were: no mulch control, gravel mulch and corn straw mulch. Corn straw and gravel were chosen, because these materials can be obtained easily in this region. Soil depth of water uptake by alfalfa moved down to deep soil quickly and seasonal rainfall became the main contributing factor after 5 years. The presence of straw on the soil surface reduced the maximum temperature, but it increased the minimum diurnal soil temperature. Straw mulch was more effective in regulating soil temperature than gravel in the pasture planting. Straw mulch and gravel mulch both enhanced soil water content at the 15cm depth. Straw mulch increased forage DMY of alfalfa by 420kgha−1 (by 6.7%) compared to no mulch control over the four growing seasons from 2009 to 2012, and gravel mulch reduced the forage DMY by 36kgha−1 (by 0.5%) during that period, but effects were not significant statistically. Straw mulch increased concentration of nitrate-N and available P in the upper soil layer significantly, and improved WUE. In conclusion, the findings suggest that alfalfa could extract water from progressively deeper soil layers and straw mulch was effective in minimizing fluctuations in soil temperature, and increasing water storage in surface shallow soil layers, forage yield and water use efficiency of alfalfa. Mulching grass hedges intercropping or contour hedgerow intercropping should be considered on sloping land.

Analysis of factors influencing population density of the peach fruit fly (PFF), Bactrocera zonata (Saunders) (Diptera: Tephritidae) in Assiut, Northern Upper Egypt

The results of this study showed that the attracted males exhibited a different response to the examined factors at two trap heights and during both study seasons (2011 and 2012) of study. However, statistical analysis indicated that the maturity level of guava fruits was the most effective variable in attracting males to methyl eugenol (ME)-baited traps hung at 1 and 2 m heights and had an effect on the average number of attracted males at the two height levels. The common rank of the independent variables according to the average number of males attracted to both height levels seemed to be as follows: guava maturation level (42.33%), maximum soil temperature (5.28%), maximum relative humidity (5.05%), minimum relative humidity (1.79%), minimum soil temperature at 5 cm depth (1.51%), maximum temperature (1.05%) and minimum temperature (0.48%). Our results suggest that trapping system consists of fly trap baited with 0.5 ml ME must be used at dawn period (the first appearance of light in the morning followed by sunrise) as peach fruit fly (PFF) males had highest activity at dawn period between 5 and 7 a.m. Traps must be hung from guava trees at 1 m height as this height was shown to be the most suitable for capturing high numbers of PFF males. The results indicate also that PFF adults could be emerged from pupae buried in the sand soil at a depth of 40 cm. At 50 cm, adults failed to emerge. Statistical analysis proved negative correlation between the emerged flies and the column weight of sand over the pupae.

Relation between soil temperature and biophysical parameters in Indian mustard seeds

Abstract Temporal changes in surface soil temperature were studied in winter crop. Significant changes in bare and cropped soil temperature were revealed. Air temperature showed a statistically positive and strong relationship (R2 = 0.79** to 0.92**) with the soil temperature both at morning and afternoon hours. Linear regression analysis indicated that each unit increase in ambient temperature would lead to increase in minimum and maximum soil temperatures by 1.04 and 1.02 degree, respectively. Statistically positive correlation was revealed among biophysical variables with the cumulative surface soil temperature. Linear and non-linear regression analysis indicated 62-69, 72-86 and 72-80% variation in Leaf area index, dry matter production and heat use efficiency in Indian mustard crop as a function of soil degree days. Below 60% variation in yield in Indian mustard was revealed as a function of soil temperature. In contrast, non-significant relationship between oil content and soil temperature was found, which suggests that oil accumulation in oilseed crops was not affected significantly by the soil temperature as an independent variable.

Miscanthus Establishment and Overwintering in the Midwest USA: A Regional Modeling Study of Crop Residue Management on Critical Minimum Soil Temperatures

Miscanthus is an intriguing cellulosic bioenergy feedstock because its aboveground productivity is high for low amounts of agrochemical inputs, but soil temperatures below −3.5°C could threaten successful cultivation in temperate regions. We used a combination of observed soil temperatures and the Agro-IBIS model to investigate how strategic residue management could reduce the risk of rhizome threatening soil temperatures. This objective was addressed using a historical (1978–2007) reconstruction of extreme minimum 10 cm soil temperatures experienced across the Midwest US and model sensitivity studies that quantified the impact of crop residue on soil temperatures. At observation sites and for simulations that had bare soil, two critical soil temperature thresholds (50% rhizome winterkill at −3.5°C and −6.0°C for different Miscanthus genotypes) were reached at rhizome planting depth (10 cm) over large geographic areas. The coldest average annual extreme 10 cm soil temperatures were between −8°C to −11°C across North Dakota, South Dakota, and Minnesota. Large portions of the region experienced 10 cm soil temperatures below −3.5°C in 75% or greater for all years, and portions of North and South Dakota, Minnesota, and Wisconsin experienced soil temperatures below −6.0°C in 50–60% of all years. For simulated management options that established varied thicknesses (1–5 cm) of miscanthus straw following harvest, extreme minimum soil temperatures increased by 2.5°C to 6°C compared to bare soil, with the greatest warming associated with thicker residue layers. While the likelihood of 10 cm soil temperatures reaching −3.5°C was greatly reduced with 2–5 cm of surface residue, portions of the Dakotas, Nebraska, Minnesota, and Wisconsin still experienced temperatures colder than −3.5°C in 50–80% of all years. Nonetheless, strategic residue management could help increase the likelihood of overwintering of miscanthus rhizomes in the first few years after establishment, although low productivity and biomass availability during these early stages could hamper such efforts.

Spatial heterogeneity in ecologically important climate variables at coarse and fine scales in a high-snow mountain landscape.

Climate plays an important role in determining the geographic ranges of species. With rapid climate change expected in the coming decades, ecologists have predicted that species ranges will shift large distances in elevation and latitude. However, most range shift assessments are based on coarse-scale climate models that ignore fine-scale heterogeneity and could fail to capture important range shift dynamics. Moreover, if climate varies dramatically over short distances, some populations of certain species may only need to migrate tens of meters between microhabitats to track their climate as opposed to hundreds of meters upward or hundreds of kilometers poleward. To address these issues, we measured climate variables that are likely important determinants of plant species distributions and abundances (snow disappearance date and soil temperature) at coarse and fine scales at Mount Rainier National Park in Washington State, USA. Coarse-scale differences across the landscape such as large changes in elevation had expected effects on climatic variables, with later snow disappearance dates and lower temperatures at higher elevations. However, locations separated by small distances (∼20 m), but differing by vegetation structure or topographic position, often experienced differences in snow disappearance date and soil temperature as great as locations separated by large distances (>1 km). Tree canopy gaps and topographic depressions experienced later snow disappearance dates than corresponding locations under intact canopy and on ridges. Additionally, locations under vegetation and on topographic ridges experienced lower maximum and higher minimum soil temperatures. The large differences in climate we observed over small distances will likely lead to complex range shift dynamics and could buffer species from the negative effects of climate change.

Moisture, thermal inertia, and the spatial distributions of near-surface soil and air temperatures: Understanding factors that promote microrefugia

Climate change poses significant threats to biodiversity, but some species may be able to escape its effects in small locations with unusual and stable climates (microrefugia). However, there are still great uncertainties about where microrefugia are located, and the exact role that moisture plays in buffering extreme temperatures. In this study we quantified the effects of moisture on the distribution and variability of near-surface soil and air temperatures. We collected hourly 1cm soil and 5cm air temperatures and humidities at 111 sites from May 2011 to March 2012. Sites were diverse in terms of elevation (2–1428m), distance from coast (180m–403km), canopy cover (0–100%), topographic exposure, and susceptibility to cold air drainage. We found that variability (diurnal range) of both soil and air temperatures decreased under moister conditions. While air temperatures were related more strongly to humidity, soil temperatures were related more to vapour pressure deficit (VPD). That is, both high temperature and low humidity were required before the VPD was sufficient to dry out the soil and allow soil temperatures to vary. We then used a regional regression approach to model the spatial distribution of minimum and maximum air and soil temperatures for each day over the 10 months in terms of latitude, elevation, canopy cover, distance to coast, cold air drainage potential, and topographic exposure to the south and northwest. We found that elevation was the dominant factor explaining the distribution of soil and air temperatures under moist conditions. Other factors, such as canopy cover and topographic exposure, had a stronger influence on air temperatures whenever humidity was low. However, these factors only affected soil temperatures at times when higher temperatures combined with low humidity to produce higher VPD. Our results provide new insights into how moisture influences the spatial distribution of near-surface soil and air temperatures. Microrefugia will be more apparent under drier conditions, but climate change may affect refugia for soil and air temperatures differently. Higher temperatures will cause VPD to increase more than would be expected by any change in humidity, and refugia in terms of soil temperatures may therefore become increasingly apparent.

Effect of Tillage on Soil Water Content and Temperature Under Freeze–Thaw Conditions

High resolution (hourly) soil water content and temperature data have been collected for nearly 10 yr within the 0–100 cm depth profiles under no‐till (NT) and conventional fall tillage (CT) practices. The data indicate significant differences between the two tillage practices, especially during winter and early spring freeze\thaw cycles. Results indicate that shallow minimum soil temperatures were lower under CT than NT; however, average winter shallow soil temperatures were very similar between the two treatments. Soil freezing characteristic curves (SFC) measured in situ with soil water content and temperature data were analyzed for differences between treatments as the NT system matured. The SFC shapes for NT evolved over a 7‐yr period as the age of the NT system increased. An intensive freeze–thaw episode showed strong hysteresis in SFC, a phenomenon not analyzed in detail before this study based on data collected in the field.

Effects of vegetation height and density on soil temperature variations

Reduction in vegetation cover caused by human activities has a great impact on soil temperature. It is important to assess how soil temperature responds to reduction of vegetation height and density. In this paper we first report the trends of mean annual soil surface and air temperatures recorded at the meteorological stations near the Ecological Research Station for Grassland Farming (ERSGF) from 1961 to 2007, then we setup an experiment using reed (Phragmites australis) stalks with different heights and densities to simulate effects of different vegetation height and density on soil and air temperatures. The warming rates of the mean annual soil and air temperatures were 0.043 and 0.041°C a−1, respectively. Changes of soil temperature were characterized by both increased mean annual maximum and minimum soil temperatures. At the experimental site, mean daily temperature, mean daily maximum soil and air temperatures increased significantly. In contrast, mean daily minimum soil temperature increased significantly while mean daily minimum air temperature decreased significantly as the height and density of reed stalks reduced during the experimental period. Mean diurnal soil temperature ranges were smaller than mean diurnal air temperature ranges. These results highlight that the importance of vegetation cover on soil and air temperatures.

Assessing the Influence of a Range of Spring Meteorological Parameters on Tree Phenology

The timing of phenological phases, such as leaf unfolding of trees, is partly driven by the weather. The impact of weather on the spring phenology of a selection of tree species in the phenological garden at Valentia Observatory, Caherciveen, County Kerry, Ireland, for the period 1967-2004 was assessed. In particular, the beginning of the growing season (BGS), as determined by the date of leaf unfolding, was considered. The impact on BGS of a range of meteorological parameters and derived parameters, including minimum, maximum and mean air temperature (°C), soil temperature (°C), rainfall (mm), sunshine (hours), number of air frost days and number of rain days was investigated. These parameters were averaged or summed over the months of February, March and April and linear regression analysis with BGS was carried out for several tree species. The results showed that the regression coefficients of BGS on minimum air and soil temperature were highest, with Populus canescens and Populus tremula showing the strongest relationships. Temperature parameters were found to be more important in driving advancing phenology than any other meteorological parameter tested.

INFLUENCE OF SOIL MOISTURE CONTENT ON SOIL SOLARIZATION EFFICIENCY

The experiments of this study were carried out to investigate how soil temperature is influenced by different soil moisture content regimes during soil solarization. The ten plots were brought to five volumetric moisture regimes (M1-M5). The moistened soils were mulched with 100-μm-thick black and transparent polyethylene covers. Maximum and minimum soil temperatures for depths of 10, 20 and 30 cm were recorded from 1 June to 30 July, 2010at Faculty of Agriculture, Omar Al-Mukhtar University, El-Beida, Libya. For black and transparent covers, the results showed that the maximum soil temperatures decreased with increasing soil moisture content. Moreover, soil solarization efficiency decreased with increasing moisture content. The higher temperatures under the M4 (0.39 and 0.37 m3/m3 at start solarization) irrigation regime resulted in faster eradication of the pathogenic fungus.

Preadaptation of Formica aquilonia and Formica lugubris ants (Hymenoptera, Formicidae) to low wintering temperatures in Northeast Asia

The ants Formica aquilonia and F. lugubris which inhabit the entire forest zone of the North Palaearctic and are absent from the basins of the Yana, Indigirka, and Kolyma rivers were found in the coastal area of the Sea of Okhotsk. A possible climatic conditionality of their occurrence in the Northeast is considered based on the data on the biotopic distribution of ants, the temperature causation of their overwintering, and cold hardiness. On the Sea of Okhotsk coast, these ants overwinter at a depth of 40–200 cm in the soil. During winter, the minimum soil temperature at a depth of 40 cm under the anthill was −5°C. The supercooling temperature of F. aquilonia was not lower than −20.2 ± 0.5°C, that of F. lugubris, not lower than −19.6 ± 0.4°C. Half of F. aquilonia individuals did not survive the daily exposure at −13°C, F. lugubris, at −16°C. These two cold-resistant species could inhabit some biotopes of the Kolyma River basin, similar to F. exsecta, F. lemani, and F. sanguinea, but they are absent there for some reasons that are not related to the temperature. A similar cold hardiness is characteristic of F. aquilonia in Estonia (Maavara, 1971, 1985), where it represents a side effect of diapause, since excessive cold hardiness has no adaptive significance for insects overwintering in the non-freezing soils of Estonia. Colonization of Siberia by ant species turned out to be possible only due to the existing cold hardiness, i.e. preadaptation to low temperature. On the Sea of Okhotsk coast, cold hardiness of the ants is non-adaptive due to the relatively mild conditions during winter.

Seedling emergence response to early sowings in unprimed and osmoprimed seeds of fiber sorghums for energy biomass under semi-arid climate

Fiber sorghum is a promising industrial crop for lignocellulosic biomass to be used for energy purposes. Limits to the adoption of early sowings (March-April) for this species are found in its thermal requirements for seed germination (>10°C). Seed osmopriming has been found to decrease the impact of low temperatures on seed germination of sorghum in laboratory. In this study, unprimed (UP) and primed (P) seed germination behavior in both laboratory at cold temperatures and open field conditions under early sowing in a typically Mediterranean environment, was examined in four cold-tolerant cultivars of fiber sorghum (Padana 4, PR 811F, Jumbo and PSE 24213). Seed germination in UP at 8°C was on average 82.4%, confirming the high cold-tolerance of all cultivars selected for the experiment. Germination was progressively delayed by the lowering of temperature from 25°C to 8°C. Seed osmopriming was effective in promoting germination speed at all temperatures in laboratory. It also resulted in an appreciable lowering of thermal time requirements for final germination. With the earliest planting date (March 10), minimum soil temperatures during the first ten days never dropped below 10.2°C, allowing a final seedling emergence of 79.2% in UP. However, low soil temperatures slowed down the rate of seed germination. At the 2nd sowing (end of March), daily maximum temperatures of soil exceeded 20°C but those minimum dropped below 10°C, slightly depressing seed germination in UP (76.3%). With the latest sowings (mid-April and early May), minimum soil temperatures always over exceeded minimum threshold for seed germination, allowing a regular seed germination in UP. Priming increased final emergence percentage in the two earliest sowings (those of March), whilst it enhanced the germination speed in all planting dates. Seed osmopriming also reduced thermal time requirements until the first seedling emerged from soil and promoted the seedling growth in all cultivars and sowing dates. These results suggest that it is possible to adopt early sowings (March) in cold-tolerant cultivars of sorghum under semi-arid climate, and that osmopriming allows the seed to partially overcome the limit imposed by cold soil to germination, contributing to a successful crop establishment when early plantings are adopted. Although the germination response to constant low temperatures in laboratory tests does not always provide a good index for predicting seedling emergence in soil under fluctuating uncontrolled temperatures, it may contribute to define desirable attributes for the identification of cultivars adapt to early sowings in the Mediterranean areas.

Soil Temperature Prediction on Farmland Water Level and Environmental Factors Paddy Based on BP-ANN Model

The main environmental factors of the influence of soil temperature are air temperature, total solar radiation, effective photosynthetic radiation, wind speed and relative humidity, while the farmland water and submerging duration are the main factors affecting the change of soil temperature, and it exist complex non linear relationship between them. The aim of this study was constructed the soil temperature prediction model on farmland water level and environmental factors and obtained paddy soil temperature predictive value by using the data of existing water level and environmental factors. For the flooding treatment, the minimum and maximum soil temperature appeared at 7:00 and 18:00, for the drought treatment the minimum and maximum soil temperature respectively appeared at 6:00 and 14:00. This study trained artificial neural network based on back propagation algorithm (BP-ANN) through the existing data to predict the four characteristics the soil temperature of different water level control so as to obtain the soil temperature amplitude. Results showed that there was certain deviation between the predictive value and the actual value at the four characteristic moments, relative error were 1.19%, 1.34%, 2.09% and 1.07%, the predicted outcome was satisfactory. It is significant for guiding the rice irrigation and the production of practice facilitated.

Hibernation and Overwinter Body Temperatures in Free-Ranging Thirteen-Lined Ground Squirrels, Ictidomys tridecemlineatus

Free-ranging, juvenile thirteen-lined ground squirrels (Ictidomys tridecemlineatus) in southwestern Michigan were fitted in late summer or fall with external skin-temperature loggers. Data were obtained the following spring for five males and three females. During the heterothermal period, all squirrels exhibited 11–22 prolonged ( = 9.4 d) torpor bouts punctuated by typically brief ( = 14.3 h) arousal bouts, with mean monthly torpor bouts becoming longer and deeper until Feb. and reversing thereafter. Torpor-bout duration increased as minimum skin and soil temperatures decreased. On average, males initiated the first torpor bout later in fall, terminated the last torpor bout significantly earlier in spring and thus spent less time in the heterothermal period than did females. Three males displayed relatively short torpor bouts and long arousal bouts as they approached the end of hibernation. Squirrels gained weight variably in fall and spring, and one female lost 39% of body mass during hibernation.

Variations in soil temperature at BJ site on the central Tibetan Plateau

The temporal and spatial variation in soil temperature play a significant role in energy and water cycle between land surface and atmosphere on the Tibetan Plateau. Based on the observed soil temperature data (hourly data from 1 January 2001 to 31 December 2005) obtained by GAME-Tibet, the diurnal, seasonal and interannual variations in soil temperature at BJ site (31.37° N, 91.90° E; 4509 a.s.l.) near Naqu in the central Tibetan Plateau were analyzed. Results showed that the average diurnal variation in soil temperature at 4 and 20 cm depth can be described as sinusoidal curve, which is consistent with the variation of solar radiation. However, the average diurnal variation in soil temperature under 60 cm was very weak. The average diurnal amplitude in soil temperature decreased by the exponential decay function with the increase of soil depth (R2=0.92, p<0.01). It is demonstrated that the average diurnal maximum soil temperature decreased by the exponential decay function with the increase of soil depth (R2 =0.78, p<0.01). In contrast, the average diurnal minimum soil temperature increased by the exponential grow function with increasing of soil depth (R2=0.86, p<0.01). There were a linear negative correlation between the average annual maximum Ts and soil depth (R2=0.96, p<0.01), a logarithmic function relationship between the average annual minimum soil temperature and soil depth (R2=0.92, p<0.01). The average seasonal amplitude in soil temperature followed the exponential decay function with the increase of soil depth (R2=0.98, p<0.01). The mean annual soil temperature in each layer indicated a warming trend prominently. During the study period, the mean annual soil temperature at 4, 20, 40, 60, 80, 100, 130, 160, 200 and 250 cm depth increased by 0.034, 0.041, 0.061, 0.056, 0.062, 0.050, 0.057, 0.051, 0.047 and 0.042 °C /a, respectively.

Effects of Hay Mulch on Soil Properties and Potato Tuber Yield under Irrigation and Nonirrigation in New Brunswick, Canada

Organic mulching and irrigation are considered to be important soil conservation and agricultural practices. However, the effectiveness of these practices on soil properties and potato production in the relatively cool, moist maritime region of Canada has not yet been well studied. In the growing seasons of 2000–2003, a field experiment was conducted at the Potato Research Centre, Agriculture and Agri-Food Canada, Fredericton, New Brunswick, to assess the benefits of hay mulching on a loamy sand soil under potato production. Treatments consisted of four levels of hay mulching: 0, 2.25, 4.5, and 9.0 Mg ha-1 with four replicates under irrigation or nonirrigation. Results showed that hay mulching could help conserve soil moisture in nonirrigation treatments with an increase of mean soil moisture content by 5.7 to 9.5% under 2.25 to 9.0 Mg ha-1 of hay mulch relative to a control. The greatest conservation effect on soil water in our region would be achieved with a mulch rate of 5.6 Mg ha-1. Under irrigation, mulching slightly increased soil temperature. Without irrigation, soil temperature was affected both positively and negatively by mulching, depending on time of day and quantity of mulch applied. During periods of warmer weather, mulching reduced maximum soil temperature during daytime but increased minimum soil temperature during nighttime. While the magnitude of soil temperature change was slight, it varied linearly with mulch quantity. During periods of cold weather, mulching generally increased soil temperature. The soil organic carbon content in the year following mulching increased proportionally with the amount of mulch applied in the nonirrigated treatments. Thus, thicker mulching treatments resulted in a greater increase in soil organic matter accumulation. Irrigation was found to potentially induce organic matter loss for the lower mulching treatment (2.25 Mg ha-1) and control. No significant effects of hay mulching on total potato tuber yield under irrigation were found, but tuber yield under nonirrigation increased linearly with the amount of mulch applied.

Models for estimation of hourly soil temperature at 5cm depth and for degree-day accumulation from minimum and maximum soil temperature

A model has been developed for the daily variation in soil temperature at 5 cm depth, for use where both the minimum and maximum temperatures are known or can be estimated. The model is based on data from three Australian sites with minute-by-minute data over 3–7 years. The model uses two sine curves; one for the increase from minimum to maximum and another for the relatively rapid decrease in temperature immediately after the maximum. An exponential decay function is used for the slower decrease in temperature until the minimum is reached. The time of the minimum soil temperature is primarily determined by the time of sunrise and therefore varies depending on the day of the year, whereas the time of the maximum temperature is influenced primarily by the time of the middle of the day (midpoint between sunrise and sunset). The time of the transition point between the maximum and the next minimum is related to the time of sunset. Therefore, the model uses latitude, longitude, and the day of the year to determine the time of sunrise and sunset to adjust the shape of the temperature profile throughout the day. The model has been validated using 3-hourly soil temperature data for 35 other sites in Australia, with a correlation of 0.993 between actual 3-hourly temperatures and those predicted. Its use for degree-day calculations has been validated using hourly data from a site in Victoria, where the model’s estimates of degree-days differ &lt;0.7% from the value based on individual hourly temperatures, whereas methods that assume a symmetrical change from maximum to minimum temperature overestimate degree-days by 6–7%.

Influence of soil hydrothermal environment, irrigation regime, and different mulches on the growth and fruit quality of strawberry (Fragaria × ananassa L.) plants in a sub-temperate climate

SummaryThe present study was undertaken over two consecutive years under sub-temperate climatic conditions in the mid-hill region of Himachal Pradesh (30°52'N, 77°11'E; 1,175 m asl) on loamy sand Inceptisols. The aim was to investigate the effects of irrigation and mulch material on the growth, flowering, fruiting behaviour, relative leaf water content (RLWC), yield, and quality of strawberry (Fragaria × ananassa L. ‘Chandler’). The drip irrigation treatments included irrigation with 100, 80, or 60% (coded 1.0, 0.8, and 0.6 V) of the total water requirement. Both mulches increased the minimum soil temperature to a depth of 5 cm. The drip and surface irrigation treatments raised the minimum soil temperature by 3.0º – 5.4ºC, and lowered the maximum temperature by 2.2º – 5.8ºC compared to the rainfed control. Hay mulch was more effective in raising the minimum temperature and lowering the maximum soil temperature than black polyethylene mulch. Moisture conservation increased by 2.8 – 12.8% under the black polyethylene mulch compared to the no-mulch treatment. Drip and surface irrigation methods, as well as mulching, were found to be effective for enhancing the growth, irrigation water use efficiency (IWUE), fruit yield, and quality of strawberry plants. However, the number of crowns per plant, the percentage berry set, the RLWC, root length density (RLD), and fruit yield were highest under treatment M3I3 [i.e., black polyethylene mulch plus drip irrigation (1.0 V)] by 565.5%, 94.5%, 32.8%, 394.5%, and 549.6%,respectively, compared to the no mulch plus rainfed control. The maximum IWUE values for plant biomass [1.39 metric tonnes (MT) ha–1 m–1] and fruit yield (2.79 MT ha–1 m–1) were recorded under treatment M3I5 [i.e., black polyethylene mulch plus drip irrigation (0.6 V)]; whereas, the lowest values (0.39 and 0.68 MT ha–1 m–1, respectively) were observed using treatment M1I2 (i.e., without mulch, plus surface irrigation). Fruit size, weight, sugar content, and anthocyanin content increased significantly under treatment M2I3 [i.e., hay mulch, plus drip irrigation (1.0 V)] compared with all other treatments. Total soluble solids (TSS) contents and total acidity (TA) were highest under treatment M1I1 (i.e., no mulch, plus rainfed). A linear regression model could describe the variations in quality parameters of strawberry plants grown under sub-temperate climatic conditions. Root density was found to be the best indicator with which estimate fruit quality.

Projection of Future Climate Change in a Non-Hydrostatic Regional Climate Model Nested within an Atmospheric General Circulation Model

Future climate change around Japan was projected with a non-hydrostatic regional climate model with a 5-km grid spacing. The future surface air temperature, averaged over all of Japan, is projected at the 99% confidence level to rise about 3°C in each month of the year. Diurnal temperature ranges are projected to increase in many areas, especially over plains on the Pacific Ocean side in February, as the warming rates of minimum temperatures are small as compare to other areas. This is due to that minimum soil temperatures of just below 0°C occur with high frequency in both the present and future climates, because they are constrained by the heat of solidification. Storm tracks are projected to approach the Japan Archipelago in February, leading to a remarkable increase in precipitation along the Pacific coast of Japan. The annual occurrence frequency of heavy precipitation is also projected to increase. The maximum snow depth is projected to decrease almost everywhere, but the changes will be small in high mountains and in northern Japan.

Symbiotic effectiveness of arbuscular mycorrhizal technology and Azotobacterization in citrus nursery production under soil disinfestation and moisture conservation practices

The present study was carried out with the objective to exploit indigenous arbuscular mycorrhizal (AM) fungal symbiosis and Azotobacterization on citrus seedlings inoculated under solarized, chemical sterilized and natural soil conditions along with moisture conservation mulch practices. Two potent indigenous species of AM fungi namely, Glomus fasciculatum (Thaxter sensu Gerdemann) (AM1) and G. macrocarpum Tul. & Tul. (AM2), and two strains of Azotobacter chroococcum viz., A. chroococcum strain-I (AZ1) and A. chroococcum strain-II (AZ2) were inoculated at nursery stage under four different moisture conservation mulch practices viz., black plastic mulch (BPM), grass mulch (GM), cover crops (CC), green manuring+clean cultivation (Gm+Cc). The effects of AM fungi and A. chroococcum strains on mycorrhizal spore population, Azotobacter bacterial count, vegetative growth characteristics and soil microbial densities (bacteria, fungi and actinobacteria) were studied. Different AM fungi showed the difference in the effectiveness of inter-species in citrus seedlings. The observations on the individual effect of soil disinfestations and mulch practices on microbial density, percent root colonization, vegetative growth characteristics (plant height, stem diameter, leaf area and total root length) and nutrient content of leaf of the seedlings were also recorded. Inoculation with G. fasciculatum and AZ1 showed greater positive effects in the seedlings compared to G. macrocarpum and AZ2 strain recording highest AM colonization, plant height, stem diameter, leaf area, root length and had the density of soil borne bacteria, fungus and actinobacteria reduced drastically in the solarized soil plots. Solarization increased the maximum daily temperature to 48.5°C and the average minimum daily soil temperature to 28.8°C at 5–25cm depth. It is also noticed that the plants inoculated with G. fasciculatum and AZ1 had improved vegetative growth characteristics, microbial consortium of the rhizosphere soil and nutrient content of leaf N, P, K and Zn under plots of solarization and black plastic mulching compared to chemical sterilized and natural plots under different mulch types. The present findings inferred that the combining soil solarization and inoculation of rhizosphere soil to AM fungi and A. chroococcum using black plastic mulching as moisture conservation practice could be considered as an efficient and feasible approach for excellent citrus nursery management under mid-hill rain-fed agro-climatic conditions of Himachal Pradesh.