Soil Moisture Treatments Research Articles

Phytoaccumulation of As by Pteris vittata supplied with phosphorus fertilizers under different soil moisture regimes – A field case

The ability of As-hyperaccumulator Pteris vittata (PV) to remove As from real As (75.2 mg/kg) contaminated farmland soils under two soil moisture treatments [water retention (WR) and non-water retention (NW)] and three types of P fertilizers (acidic, alkaline and weakly acidic P fertilizers, indicated by SSP, CaP and KP, respectively) under field condition over 5 months was investigated for the first time. The results showed that yields of PV were increased by water retention irrespectively of P treatments. The results revealed that the uptake of As by PV was significantly increased by CaP and KP treatments, the opposite was observed with SSP treatment. Under WR condition, the uptake of As by PV treated with CaP and KP treatments was further significantly increased compared with SSP treatment. This study suggested that the combination of P fertilizer with soil moisture control is a more promising approach to increase remediating efficiency of PV under the real field conditions.

Bioenergy from Periodically Waterlogged Cropland in Europe: A First Assessment of the Potential of Five Perennial Energy Crops to Provide Biomass and Their Interactions with Soil

Harvesting of silage maize in late autumn on waterlogged soils may result in several ecological problems such as soil compaction and may subsequently be a major threat to soil fertility in Europe. It was hypothesized that perennial energy crops might reduce the vulnerability for soil compaction through earlier harvest dates and improved soil stability. However, the performance of such crops to be grown on soil that are periodically waterlogged and implications for soil chemical and microbial properties are currently an open issue. Within the framework of a two-year pot experiment we investigated the potential of the cup plant (Silphium perfoliatum L.), Jerusalem artichoke (Helianthus tuberosus), giant knotweed (Fallopia japonicum × bohemica), tall wheatgrass (Agropyron elongatum), and reed canary grass (Phalaris arundinacea) for cultivation under periodically waterlogged soil conditions during the winter half year and implications for soil chemical and biological properties. Examined perennial energy crops coped with periodical waterlogging and showed yields 50% to 150% higher than in the control which was never faced with waterlogging. Root formation was similar in waterlogged and non-waterlogged soil layers. Soil chemical and microbial properties clearly responded to different soil moisture treatments. For example, dehydrogenase activity was two to four times higher in the periodically waterlogged treatment compared to the control. Despite waterlogging, aerobic microbial activity was significantly elevated indicating morphological and metabolic adaptation of the perennial crops to withstand waterlogged conditions. Thus, our results reveal first evidence of a site-adapted biomass production on periodical waterlogged soils through the cultivation of perennial energy crops and for intense plant microbe interactions.

Functional Traits Explain Variation in Chaparral Shrub Sensitivity to Altered Water and Nutrient Availability.

Worldwide drylands are threatened by changes in resource availability associated with global environmental change. Functional traits may help predict which species will be most responsive to these alterations in nutrient and water availability. Current functional trait work focuses on tissue construction and nutrient concentrations, but plant performance in low resource environments also may be strongly influenced by traits related to nutrient budgets and allocation. Our overall objective was to compare trait responses in a suite of serpentine and nonserpentine congener pairs from the California chaparral, a biodiverse region facing nutrient deposition and future changes in precipitation. In a common garden greenhouse environment, we grew small plants of Arctostaphylos manzanita, A. viscida, Ceanothus cuneatus, C. jepsonii, Quercus berberidifolia, and Q. durata in contrasting soil nutrient and moisture treatments. We measured a suite of traits representing physiological, growth, and mineral nutrient responses to these treatments. Overall, plant growth rate and leaf-level phosphorus use efficiency were greatest in the low water, high nutrient treatment, and lowest in the high water, low nutrient treatment. Variation in growth rate and plasticity among species and treatments was primarily associated with differences in mineral nutrition-based traits as opposed to differences in biomass allocation or specific leaf area. Namely, faster growing species and species with greater plasticity allocated more nitrogen and phosphorous to leaves and demonstrated greater photosynthetic phosphorus use efficiency. Overall, nonserpentine species had greater plasticity and biomass response to resource addition than serpentine species, and congener pairs responded to these resource additions more similarly to each other than species across congener pairs. This study extends our general understanding of how functional traits may influence species responses to environmental change and highlights the need to integrate mineral nutrition-based traits, including allocation of nutrient pools and nutrient use efficiency into this larger trait framework. Ultimately, this insight can help identify, in part, why coexisting species may vary in sensitivity to anthropogenic driven changes in soil resource availability.

Earthworm activity and availability for meadow birds is restricted in intensively managed grasslands

Abstract Earthworms are an important prey for the endangered meadow birds of northwest Europe. Although intensive grassland management with high manure inputs generally promotes earthworm abundance, it may reduce the effective food availability for meadow birds through desiccation of the topsoil, which causes earthworms to remain deeper in the soil. We studied the response of Red Worm Lumbricus rubellus, a detritivore, and Grey Worm Aporrectodea caliginosa, a geophage, to soil moisture profiles in the field and under experimental conditions. Surfacing earthworms were counted weekly in eight intensively managed grasslands (treated with high inputs of slurry by slit injection) with variable groundwater tables in the Netherlands. At each count, soil penetration resistance, soil moisture tension and groundwater level were measured, while air temperature and humidity were obtained from a nearby weather station. The response to variation in the vertical distribution of soil moisture was also experimentally studied in the two earthworm species. In the field, earthworms’ surfacing activity at night was negatively associated with soil moisture tension and positively by relative air humidity. Surprisingly, there was no effect of groundwater level; an important management variable in meadow bird conservation. Under experimental conditions, both L. rubellus and A. caliginosa moved to deeper soil layers (>20 cm) in drier soil moisture treatments, avoiding the upper layer when moisture levels dropped below 30%. Synthesis and applications. We propose that in intensively managed grasslands with slurry application, topsoil desiccation reduces earthworm availability for meadow birds. This can be counteracted by keeping soil moisture tensions of the top soil above −15 kPa. We suggest that the late raising of groundwater tables in spring and the disturbance of the soil by slit injection of slurry increase topsoil desiccation. This decreases earthworm availability when it matters most for breeding meadow birds. Meadow bird conservation will benefit from revised manure application strategies that promote earthworm activity near or at the soil surface.

Response of adult sour cherry trees to woodchip mulch and drip irrigation

The aim of this study was to evaluate the growth, productivity, and tree condition of sour cherries, depending on the cultivar and soil-moisture treatment. The research was carried out at the Institute of Horticulture, Latvia University of Agriculture. Five sour cherry cultivars were investigated using drip irrigation and woodchip mulch. The following data were collected and processed: trunk cross-section area (TCSA), trunk growth intensity (TGI), fruit set, yield tree(-1) and yield efficiency as a ratio of TCSA, photosynthesis performance index, and the level of defoliation caused by cherry leaf spot after natural infection in the field. Woodchip mulch preserved soil moisture at optimal levels or higher during most vegetation seasons. Sour cherry cultivars differed significantly in terms of growth, productivity, and tree condition, and in the response to soil-moisture treatment. Most of the sour cherry cultivars responded to drip irrigation and woodchip mulch by increasing the growth and productivity of trees; however, a negative (in 'Orlica') or minimal (in 'Bulatnikovskaya') effect of mulch was observed in a few cultivars. Our study highlights the variability of sour cherry cultivars and the necessity of further research before recommendations can be made to growers.

Genotypic differences in growth behavior and quality parameters of sugarcane (Saccharum officinarum) varieties under moisture stress conditions

A field experiment was conducted at CCS Haryana Agricultural University, Regional Research Station, Karnal to investigate the effect of available soil moisture regimes on productivity potential of sugarcane (Saccharum officinarum L.) varieties during 2014-15 and 2015-16. The experiment consists of three moisture regimes based on available soil moisture (ASM), i.e. irrigation at 50% ASM (control), 40% ASM (mild stress) and 30% ASM (severe stress) in main plots and four commercial sugarcane varieties differing in maturity duration, i.e. CoS 767 (Mid late), CoH 128 (Mid late), CoJ 64 (Early) and Co 0238 (Early) in sub plot was laid out in split-plot design with three replications. Soil moisture treatments were initiated after 45 days of planting (DAP). Higher germination was recorded in CoJ 64 (65.5%) and CoS 767 (58.0%) as compared to Co 0238 (49.0%) and CoH 128 (48.5%) at 45 DAP. At 30% ASM levels, higher reduction in stalk height was recorded in CoH 128 (33.6 and 85.96 cm) and CoJ 64 (36.33 and 83.03cm) as compared to CoS 767 (41.83 and 107.06 cm) and Co 0238 (50.6 and 122.76 cm) in June and July, respectively. Total number of tillers was reduced by 12.99, 14.37 and 14.5% at 40% ASM level and 16.97, 24.29 and 20.04% at 30% ASM level as compared to irrigation at 50% ASM level in the month of May, June and July, respectively. Significantly higher values of brix, pol and CCS (%) were recorded in CoJ 64 and Co 0238 as compared to CoS 767 and CoH 128 at 8th, 10th and 12th month at all levels of ASM. Varieties and ASM levels had no effect on the specific activity of sucrose synthase. Sugar yield significantly reduced by 31.11 per cent at 40% ASM level and 40.57 per cent at 30% ASM level, respectively as compared to 50% ASM level. Co 0238 and CoS 767 showed minimum reduction in yield than CoH 128 and CoJ 64. From the present study it is concluded that Co 0238 and CoS 767 are identified relatively more tolerant at 30% and 40% ASM levels than CoH 128 and CoJ 64.

Study of soil respiration and fruit quality of table grape (Vitis vinifera L.) in response to different soil water content in a greenhouse

ABSTRACTTo understand the response of grape (Hutai No.8) quality and soil respiration (Rs) to different soil relative water contents (SRWCs), this study was designed with three soil moisture levels (A: 80–95%, B: 60–75%, and C: 40–55% of SRWC) for grape cultivation. Meanwhile, environmental factors, including air temperature (Ta), air relative humidity, and light intensity, were also recorded. The results showed the following: (1) Through the comprehensive analysis of fruit quality by the method of subordinate function, we concluded that the optimum soil moisture treatment was 60–75% SRWC, and the soluble sugars, proanthocyanidin, and resveratrol were most abundant. In addition, vitamin C (Vc) content was the largest under C treatment. (2) Photosynthetic characteristic under high soil moisture was better than those under low soil moisture condition during grape coloring periods, and it was largest under A treatment in 2015. Rs rate was in accordance with the trend of grape photosynthesis. High soil moisture could accelerate the photosynthetic rate of grape leaves and increase Rs. (3) Correlation analysis showed that higher soil moisture and air humidity and lower soil temperature (Ts) and Ta could promote the accumulation of more nutrients in grape berries; it also could increase photosynthetic rate and Rs during grape coloring periods. In conclusion, 60–75% SRWC was the optimum soil moisture condition, which could improve the nutrient contents and accumulate more bioactive substances. Of course, keeping a lower Ts and Ta, as well as higher air humidity, was also necessary.Abbreviations: SRWC: soil relative water content; A, 90-95% SRWC; B, 70-75% SRWC; C, 40-55% SRWC; Rs: soil respiration; Ta: air temperature; Ts: soil temperature; OPC: proanthocyanidin; TSS: total soluble solids.

Effect of Cultivar, Ethephon, Flooding, and Storage Duration on Sweetpotato Internal Necrosis

The reason for internal necrosis occurrences in sweetpotato (Ipomoea batatas) storage roots is not well understood. This disorder begins internally in the storage roots as small light brown spots near the proximal end of the root that eventually can become more enlarged as brown/black regions in the cortex. The objective of this study was to determine the effect of ethephon and flooding on the development of internal necrosis in the sweetpotato cultivars Beauregard, Carolina Ruby, and Covington over storage durations from 9 to 150 days after harvest (DAH) when roots had been cured. Soil moisture treatments were no-flooding, and simulated flooding that was created by applying 10 inches of overhead irrigation during 2 weeks before harvest. Ethephon was applied at 0, 0.75, and 0.98 lb/acre 2 weeks before harvest. Overall, ‘Covington’ and ‘Carolina Ruby’ had greater internal necrosis incidence (22% to 65% and 32% to 51%, respectively) followed by ‘Beauregard’ (9% to 22%) during storage duration from 9 to 150 DAH at both soil moistures. No significant change was observed for either internal necrosis incidence or severity for ‘Beauregard’ and ‘Carolina Ruby’ over the storage duration of 9–150 DAH. However, there was an increase of internal necrosis incidence and severity 9–30 DAH in ‘Covington’, with incidence and severity remaining similar 30–150 DAH. Storage roots in treatments sprayed with 0.75 or 0.98 lb/acre ethephon had higher internal necrosis incidence and severity compared with the nontreated, regardless of cultivars at both soil moistures. This research confirms that sweetpotato cultivars differ in their susceptibility to internal necrosis (incidence and severity), ethephon applied to foliage can contribute to internal necrosis development in storage roots, and internal necrosis incidence reaches a maximum by 30 DAH in ‘Covington’ and 9 DAH in ‘Carolina Ruby’ and ‘Beauregard’.

Stand development and other intrinsic factors largely control fine-root dynamics with only subtle modifications from resource availability

Forest productivity depends on resource acquisition by ephemeral roots and leaves. A combination of intrinsic and environmental factors influences ephemeral organs; however, difficulties in studying belowground organs impede mechanistic understanding of fine-root production and turnover. To quantify factors controlling fine-root dynamics, we grew a deciduous hardwood (Populus deltoides Bartr.) and an evergreen conifer (Pinus taeda L.) with distinct soil moisture and nutrient availability treatments. We monitored fine-root dynamics with minirhizotrons for 6 years during early stand development and expressed results on a root length, biomass and mortality-risk basis. Stand development and other intrinsic factors consistently influenced both species in the same direction and by similar magnitude. Live-root length increased to a peak during establishment and slowly declined after roots of neighboring trees overlapped. Root longevity was highest during establishment and decreased thereafter. Root longevity consistently increased with depth of appearance and initial root diameter. Season of appearance affected root longevity in the following order: spring > summer > fall > winter. The influence of soil resource availability on fine-root dynamics was inconsistent between species, and ranked below that of rooting depth, initial diameter, stand development and phenology. Fine-root biomass either increased or was unaffected by greater resource availability. Fine-root production and live root length decreased with irrigation for both species, and increased with fertilization only for poplar. Fine-root mortality risk both increased and decreased depending on species and amendment treatment. Differing responses to soil moisture and nutrient availability between species suggests we should carefully evaluate generalizations about the response of fine-root dynamics to resource availability. While attempting to describe and explain carbon allocation to fine-root production and turnover, modelers and physiologists should first consider consistent patterns of allocation caused by different depth, diameter, stand development, phenology and species before considering allocation due to soil resource availability.

Phloem Girdling of Norway Spruce Alters Quantity and Quality of Wood Formation in Roots Particularly Under Drought.

Carbon (C) availability plays an essential role in tree growth and wood formation. We evaluated the hypothesis that a decrease in C availability (i) triggers mobilization of C reserves in the coarse roots of Picea abies to maintain growth and (ii) causes modification of wood structure notably under drought. The 6-year-old saplings were subjected to two levels of soil moisture (watered versus drought conditions) and root C status was manipulated by physically blocking phloem transport in the stem at three girdling dates (GDs). Stem girdling was done before the onset of bud break [day of the year (doy) 77], during vigorous aboveground shoot and radial stem growth (GD doy 138), and after cessation of shoot growth (GD doy 190). The effect of blockage of C transport on root growth, root phenology, and wood anatomical traits [cell lumen diameter (CLD) and cell wall thickness (CWT)] in earlywood (EW) and latewood (LW) was determined. To evaluate changes in belowground C status caused by girdling, non-structural carbohydrates (soluble sugars and starch) in coarse roots were determined at the time of girdling and after the growing season. Although fine root mass significantly decreased in response to blockage of phloem C transport, the phenology of root elongation growth was not affected. Surprisingly, radial root growth and CLD of EW tracheids in coarse roots were strikingly increased in drought-stressed trees, when girdling occurred before bud break or during aboveground stem growth. In watered trees, the growth response to girdling was less distinct, but the CWT of EW significantly increased. Starch reserves in the roots of girdled trees significantly decreased in both soil moisture treatments and at all GDs. We conclude that (i) radial growth and wood development in coarse roots of P. abies saplings are not only dependent on current photosynthates, and (ii) blockage of phloem transport induces physiological changes that outweigh drought effects imposed on root cambial activity and cell differentiation.

Effects of UV-B Radiation on Soil Carbon and Nitrogen Transformation under Different Soil Moisture Contents from Two Paddy Fields

Carbon and nitrogen in soils play an important role in the global carbon and nitrogen cycle. The enhancement of ultraviolet radiation (predominantly UV-B) resulting from the depletion of stratospheric ozone has raised significant concern. The effects of UV-B radiation on soil carbon and nitrogen transformation is connected directly to the physical and chemical properties of the soil. In order to clearly understand the effects of soil moisture on UV-B radiation, this study collected soil samples from two paddy fields with different levels of organic matter in a subtropical region of China. The response of the total organic carbon (TOC), dissolved organic carbon (DOC), ammonia nitrogen (NH4+ -N), nitrate nitrogen (NO3- -N) and cumulative net nitrogen mineralization to UV-B radiation under three different moisture gradients (W1=25%, W2=50%, and W3=100%) were monitored in laboratory for 120 h. After this period, the results were compared with a control treatment (CK) and it was found that:the TOC content had significantly decreased under UV-B radiation (p<0.05). From low to high moisture content (W1, W2 and W3), the TOC decreased by 9.9%, 4.5% and 6.3%, respectively for soil with low organic matter (L), and by 10.9%, 5.6% and 6.3%, respectively for soil with high organic matter (H), under UV-B radiation. However, UV-B radiation was found to enhance the DOC content in the soil compared with the CK. Furthermore, the DOC for soil moisture contents under 100% (W3) was higher than for other moisture contents (W1, W2). The measured DOC increased by 21.5% (W1), 9.4% (W2), and 26.3% (W3) for soil with L. In addition, the measured DOC increased by 26.7% (W1), 14.2% (W2) and 33.8% (W3) for soil with H under UV-B radiation after 120 h. Compared with control treatment (CK), UV-B radiation decreased the NH4+ -N content significantly, but there was an increased NO3- -N content. The decrease of the NH4+ -N content was largest for W3 and smallest for W1. The increase in NO3- -N content was largest for W2 and smallest for W1 for the two soil samples under UV-B radiation. UV-B radiation demonstrated an obvious effect on the cumulative net nitrogen mineralization (p<0.05) after 24 h compared with the CK and the effect of different soil moisture treatment was also significant (p<0.05). Overall, light degradation played a major role in the stabilization of soil organic matter, soil moisture, and UV-B radiation could accelerate the loss of soil organic carbon and has a major impact on the transformation of mineral nitrogen in the soil. Therefore, in agricultural production systems, completely bare surfaces should be avoided. For example, paddy rice-upland crop rotation systems could reduce the use of fallow periods.

Polyamines and ethylene in rice young panicles in response to soil drought during panicle differentiation

This study tested the hypothesis that polyamines (PA) and ethylene (ETH) mediate the effects of soil drought on spikelet development in rice (Oryza sativa L.). Two rice cultivars, Yong You-2640 and Yang Dao-6, with vastly different panicle sizes were grown in pots under three soil moisture treatments: well-watered (WW), moderate soil drought (MD) and severe soil drought (SD), from the onset of panicle initiation to the pollen completion stage. MD treatment significantly increased spikelet differentiation, spikelet number per panicle, fully filled grain percentage and grain yield, decreasing the percentage of degenerated spikelets, sterile spikelets and partially filled grains compared to WW treatment. In contrast, SD treatment showed opposite effects. MD also increased the contents of free spermidine (Spd), free spermine (Spm) and the ratios of free putrescine, free-Spd and free-Spm to 1-aminocylopropane-1-carboxylic acid (ACC), decreasing the ETH evolution rate and ACC content in young panicles. In contrast, SD treatment showed opposite effects. Furthermore, free-Spd and free-Spm contents increased significantly, while ETH and ACC levels, and the percentage of degenerated and sterile spikelets decreased significantly under application of Spd or an inhibitor of ETH synthesis. The results were reversed when ACC or an inhibitor of Spd and Spm synthesis was applied. These findings suggest antagonistic interactions between free-PA (Spd and Spm) and ETH in response to soil drought, mediating spikelet development in rice.

Half-sibling loblolly pine clones exhibited intraspecific variation, a G × E interaction, and differences in stable isotope composition in response to soil moisture availability

We examined the response of three loblolly pine half-sibling clones (hereafter referred to as Clone 1, 2, and 3) to soil moisture availability in a greenhouse study. Three soil moisture treatments were imposed. Two were constant soil moisture treatments at either high (−0.3MPa) or low (−1.5MPa) soil water potential. The third was an alternating wet-dry treatment that alternated between one week at high (−0.3MPa) and three weeks at low (−1.5MPa) soil water potential, which simulated several natural wetting-drying cycles. At intervals throughout the experiment we measured biomass accumulation (via sequential harvesting), change in height, pre-dawn needle water potential, afternoon needle water potential, dark respiration, and morning and afternoon gas exchange (photosynthesis, stomatal conductance, intercellular CO2, and transpiration). Carbon allocation to root and shoot biomass, stomatal density, and carbon isotope composition were measured at the end of the experiment.All clones accumulated more biomass in the high soil moisture treatment than in the low soil moisture treatment, but there was a genetic by environment (G×E) interaction: Clone 1 accumulated more biomass than the other clones in the low soil moisture treatment and less than the others in the high soil moisture treatment. Stable carbon isotope composition, which we interpreted as a time-integrated index of water use efficiency, was significantly higher (indicating greater water use efficiency) in Clone 2, compared to Clones 1 and 3 across all soil moisture treatments except in the wet-dry treatment, where Clone 1 and 3 were not significantly different. A strong negative correlation was found between stable carbon isotope composition and biomass accumulation. Gas exchange parameters and needle water potential were higher in the high soil moisture treatment compared to the other treatments across all clones. Morning measurements of gas exchange were higher in Clones 2 and 3 than in Clone 1 across all treatments. Stomatal density varied significantly among clones but not among treatments. These results demonstrated that closely related clones differed in their growth and physiological responses to moisture availability, suggesting that clonal variation could be used to breed for increased drought resistance or to identify drought resistant genotypes for selective deployment.

Observations of the Germination Behavior of &amp;lt;i&amp;gt;Tilletia indica&amp;lt;/i&amp;gt; Teliospores on the Soil Surface under Varying Simulated Environmental Conditions

A series of replicated growth chamber studies were conducted to determine the effects of soil type and simulated European temperature conditions from fall planting to anthesis in Hungary, United Kingdom, Italy and Norway on the initiation of Tilletia indica teliospore germination on the soil surface. A concurrent study examined effects on teliospore germination of a simulated temperature profile for Ciudad Obregon, Mexico, where Karnal bunt is known to occur. Three soil moisture treatments were tested; 40.5% water holding capacity (WHC), 16.2% WHC and weekly fluctuation of soil WHC. Results suggest that soil type would not have a significant effect on germination during the cropping season. Under all conditions tested, some portion of the teliospore population remained dormant but viable throughout the entire season. In comparing Mexican and Hungarian temperature profiles, highest soil surface germination for the Hungarian profile was at 40.5% WHC during the first 30 days of the simulation (30 days after planting date). The highest germination for the Mexican profile was at the 16.2% WHC during the last 30 days of the study (time of anthesis).

Influence of Soil Moisture Stress on Vegetative Growth and Mycorrhizal Colonization in Hound’s-tongue (Cynoglossum officinale)

Hound’s-tongue is an invasive, biennial weed that thrives in dry rangelands of British Columbia. Rosette formation in the first year of growth and a deep root system offer this weed a competitive advantage against associated grasses under dry conditions. To study effects of water stress on seedling growth and mycorrhizal colonization in hound’s-tongue, seedlings of this weed were grown in pots in a greenhouse and subjected to four (100, 80, 60, and 40% of field capacity) soil moisture treatments. Effects of soil moisture stress (SMS) on several growth parameters as well as mycorrhizal colonization of roots were studied. The total biomass, shoot and root fresh and dry weights, leaf number, petiole length, leaf area, and specific leaf weight (leaf dry weight per unit leaf area) decreased with increasing SMS; shoot and root water content was not affected. Because of a greater effect of SMS on root compared with the shoot biomass, shoot:root ratio increased as the moisture stress increased. Water stress decreased mycorrhizal colonization and arbuscule and vesicle abundance. A reduction in total biomass, leaf number and leaf area per plant, petiole length, and mycorrhizal colonization may reduce the competitive advantage of hound’s-tongue over its neighbors under drought conditions. The effect on plant size may also influence herbivory, by biocontrol agents and other herbivores, and fecundity of this weed.

Winter hardiness of sour cherries influenced by cultivar and soil moisture treatment

Winter hardiness of sour cherries influenced by cultivar and soil moisture treatment

The effect of peat and iron supplements on the severity of potato common scab and bacterial community in tuberosphere soil.

The control of common scab (CS) of potatoes includes resistant cultivars, specific fertilization, increase of soil moisture and chemical treatments. Yet, these management practices do not have common or reproducible results at differing sites. In order to determine the effects of soil organic matter, iron and pH on CS development, peat and DTPA-chelated iron were supplemented to pots filled with soil conducive for CS. All results were compared with the same data obtained for a suppressive soil, which has naturally low severity of CS and occurs nearby. Bacteria, Actinobacteria and the txtB genes from the biosynthetic cluster of thaxtomin, which is responsible for the disease development, were quantified by qPCR in tuberosphere soil and potato periderm. Illumina amplicon sequencing of bacterial 16S rRNA genes was performed for tuberosphere soils. Both peat and iron supplements controlled potato scab, and the combination of the two supplements reduced CS most effectively. The bacterial community was modified by all treatments but the highest number of operational taxonomic units (OTUs) changed towards the suppressive soil after the combined peat and iron treatment. It seemed that iron supplement supported plant defense while both iron and peat additions changed the bacterial community in favor of CS suppression.

Effects of water-controlled irrigation on maize yield and photosynthetic characteristics of ear leaf in Xinjiang Province, China.

In order to explore the suitable water management patterns for high yield of spring maize under drip irrigation in oasis regions of North Xinjiang, two maize cultivars (Zhengdan 958 and Kenyu 02) were used to study the effect of water-controlled irrigation on the leaf SPAD value at V12-R5 stage, and chlorophyll content, photosyntheticcharacteristics and chlorophyll fluorescence parameters of ear leaf at filling stage in the field. Results showed that the leaf SPAD values peaked under moderate soil moisture treatments during V12-R3 stage. The field capacity of soil moisture above 65% was suitable for the development of corn at R5 stage. The chlorophyll a, b and total chlorophyll contents, carotene, chlorophyll a/b were significantly decreased when soil moisture was less than 75%, however the above parameters had no significant difference when soil moisture was more than 85%. The net photosynthetic rate (Pn), transpiration rate (Tr) and stomata conductance (gs) of ear leaf were significantly decreased in filling stages when soil moisture was less than 75%, but the intercellular CO2 concentration (Ci) was significantly increased. The reduction of gs was not observed when the soil moisture was more than 85% of field capacities. Meanwhile, the variable fluorescence to maximal fluorescence (Fv/Fm), potential activities of PSII (Fv/Fo), PS2 actual photochemical efficiency (ΦPS2), photochemical quenching (qP) and electron transport rate (rETR) decreased significantly under both higher and lower soil moisture treatments. However, the Fo/Fm and non-photochemical quenching (NPQ) significantly increased at the same time. The path analysis showed that the decrease of Pn resulted from the decrease of Fv/Fo and rETR, which finally resulted in decreased production of spring maize. Therefore, the optimal field moistures for these two spring maize cultivars were >60%, >70%, >75%, >80% and >65% for the growing stages V6, V12, R1, R3 and R5, respectively, to obtain a high yield in the oasis region.

Conserved water use improves the yield performance of soybean (Glycine max (L.) Merr.) under drought

We evaluated the importance of conserved water use in drought adaptation in soybean [Glycine max (L.) Merr.], and identified the traits involved in this mechanism. Eight soybean genotypes, four landraces and four recent cultivars, were collected and yield performance in the field was determined and used in pot experiments to evaluate the yield performance and the water use pattern under three soil moisture treatments imposed from 40days after sowing: well-watered [WW, soil water content (SWC) maintained between 85%–100% field capacity (FC)]; water stress (WS, water withheld until SWC decreased to 30% FC, rewatered to 100% FC and water withheld again to 30% FC); and terminal water stress (TWS, water withheld until maturity). The recent cultivars all out-yielded the landraces in two different years in the field and under well-watered conditions in the pot experiment. Among the eight soybean genotypes, J19 and ZH – two recent cultivars with lower daily water use before flowering, but higher use after flowering – had the best yield performance in the WS and TWS treatments in the pot experiment and in the field. These two soybean genotypes and J19, another recent cultivar, had higher grain yield, hundred-grain weights and water use efficiency for grain yield (WUEG) in the WS treatments than the other genotypes, and higher hundred grain weights, higher WUEG, higher pod numbers and the only significant grain yield in the TWS treatment. J19 and ZH had low root length densities (RLD), low leaf areas at flowering, and transpiration decreased at high plant available soil water content under drought. Thus, we conclude that reducing RLD and restricting water loss contributed to conserved water use and improved yield performance and WUEG in water-limited conditions.

Cell Wall Ultrastructure of Stem Wood, Roots, and Needles of a Conifer Varies in Response to Moisture Availability

The composition, integrity, and architecture of the macromolecular matrix of cell walls, collectively referred to as cell wall ultrastructure, exhibits variation across species and organs and among cell types within organs. Indirect approaches have suggested that modifications to cell wall ultrastructure occur in response to abiotic stress; however, modifications have not been directly observed. Glycome profiling was used to study cell wall ultrastructure by examining variation in composition and extractability of non-cellulosic glycans in cell walls of stem wood, roots, and needles of loblolly pine saplings exposed to high and low soil moisture. Soil moisture influenced physiological processes and the overall composition and extractability of cell wall components differed as a function of soil moisture treatments. The strongest response of cell wall ultrastructure to soil moisture was increased extractability of pectic backbone epitopes in the low soil moisture treatment. The higher abundance of these pectic backbone epitopes in the oxalate extract indicate that the loosening of cell wall pectic components could be associated with the release of pectic signals as a stress response. The increased extractability of pectic backbone epitopes in response to low soil moisture availability was more pronounced in stem wood than in roots or needles. Additional responses to low soil moisture availability were observed in lignin-associated carbohydrates released in chlorite extracts of stem wood, including an increased abundance of pectic arabinogalactan epitopes. Overall, these results indicate that cell walls of loblolly pine organs undergo changes in their ultrastructural composition and extractability as a response to soil moisture availability and that cell walls of the stem wood are more responsive to low soil moisture availability compared to cell walls of roots and needles. To our knowledge, this is the first direct evidence, delineated by glycomic analyses, that abiotic stress affects cell wall ultrastructure. This study is also unique in that glycome profiling of pine needles has never before been reported.