Root Zone Research Articles

Study on Plant Growth Promoting Traits of PGPR Isolates From Semi-Arid Kachchh, Gujarat Under Salt Stress Conditions

Salinity is a major problem in the agricultural sector, as it turns productive agronomical land to become unproductive. Therefore, Plant-growth-promoting rhizobacteria (PGPR), that live in the plant root zone named the rhizosphere, is one of the prominent solutions to overcome this problem in an eco-friendly manner as Rhizobacteria responds to osmotic stress and support plant development. Thus, the present study was aimed to characterize various traits of the PGPR strains isolated from saline soils of Kachchh. The characterization of the traits in the presence and absence of sodium chloride was assessed including IAA production (76.97±1.68 mg/l), Ammonia production (38.59±0.19 mg/l), Siderophore production (49.21±1.83%), Phosphate solubilization (4897.73±25.53 mg/l). When assessed for the salt tolerance of the strains in the presence of NaCl between 20-50 gm/L, the strain D6 exhibited a better growth even at 5% NaCl concentration (2.047OD). Further, the effect of PGPR on the growth of V. radiata was 100% in all the experimental setup, whereas in case of B. juncea, the highest germination of 96.67% was observed only in T2 and T1+T2+T3. Further, the molecular sequencing of the strains revealed the identification of the strains as Klebsiella quasipneumoniae, Bacillus paralicheniformis and Klebsiella pneumoniae.

Water use characteristics and the mechanism of water uptake in two typical sand-fixing species in Mu Us sandy land

Understanding water absorption mechanisms of sand-fixing plants is important for the rational establishment of plant community structures, thereby providing a scientific basis for desertification control and the efficient utilization of water resources in sandy areas. Based on the hydrogen and oxygen isotopic compositions of precipi-tation, soil water, xylem water, and groundwater, coupled with soil water-heat dynamics, annual water consumption characteristics of vegetation, using the multi-source linear mixing model (IsoSource), we analyzed the differences in water sources between Salix psammophila and Artemisia ordosica, during winter and the growing season. We further examined the effects of groundwater depth (2 m and 10 m), soil freezing-thawing, and drought on their water utilization to elucidate water absorption mechanisms of those species. The results showed that: 1) During soil freezing-thawing period (January to March), S. psammophila mainly utilized soil water in 60-120 cm depths below the frozen layer (69.1%). In the green-up season (April and May), soil water from the 0-60 cm layers could satisfy the water demand of S. psammophila (30.9%-87.6%). During the dry period of the growing season (June), it predominantly utilized soil water at the depth of 120-160 cm (27.4%-40.8%). Over the rainy season (July and September), soil water in 0-60 cm depths provided 59.8%-67.9% of the total water required. A. ordosica, with shallow roots, could not utilize soil water after complete freezing of root zone but could overwinter by storing water in rhizomes during autumn. During the growing season, it primarily relied on 0-40 cm soil layer (23.4%-86.8%). During the dry period, it mainly utilized soil water from 40-80 cm and 80-160 cm soil layers, with utilization rates of 14.6%-74.4% and 21.8%-78.2%, respectively. 2) With decreasing groundwater depth, vegetation shifted its water absorption depth upward, with water source of S. psammophila transitioning from 120-160 cm to 60-160 cm layers, while A. ordosica shifted water absorption depth from 80-160 cm to 0-40 cm. S. psammophila's utilization of soil water is influenced by transpiration, adopting an "on-demand" approach to achieve a balance between water supply and energy conservation, whereas A. ordosica tends to utilize shallow soil water, exhibiting a higher depen-dence on water sources from a single soil layer.

Distinguishing the effects of micro‐ and macro‐habitats on plant‐associated microbiomes in the Qinghai‐Tibetan Qaidam Basin

AbstractAlthough microbiomes associated with plants and the environment are intricately intertwined, it remains unclear how various environmental scales affect these relationships differently. We employed high‐throughput amplicon sequencing to examine the plant‐associated bacterial and fungal communities across three different micro‐habitats (leaf, root, and root zone soil) in 16 shrubs distributed across a >500 km transect of the eastern Qinghai‐Tibetan Qaidam Basin. Among the three microhabitats, the diversity and composition of plant‐associated bacterial and fungal communities differed significantly. Although micro‐habitats play a crucial role in shaping plant‐associated microbial communities, geographic and climatic variables largely influenced the community compositions across the three micro‐habitats. Notably, the microbial communities in all three micro‐habitats showed significant distance‐decay patterns. Furthermore, fungi exhibited less variation across the three microenvironments, and were more sensitive to environmental changes than bacteria. Moreover, microbiome complexity and stochasticity gradually increased from soils to roots and finally to leaves. The microbial communities in soils and epiphytes (leaves and roots) were predominantly shaped by determinism and stochasticity, respectively. These results highlight that plant‐associated microbiomes are primarily shaped by the microenvironments associated with plants; however, their compositions, dynamics, and assembly are further influenced by geographic and climatic factors. Overall, our findings greatly increase our understanding of the intricate dynamics between plant‐associated microbiomes and their surrounding environment in drylands. This knowledge contributes to ongoing research on microbial ecology and provides substantial supports for the precise evaluation of desert ecosystem function. The findings are helpful for biodiversity conservation and sustainable management of desert shrublands.

Raising root zone temperature improves plant productivity and metabolites in hydroponic lettuce production.

While it is commonly understood that air temperature can greatly affect the process of photosynthesis and the growth of higher plants, the impact of root zone temperature (RZT) on plant growth, metabolism, essential elements, as well as key metabolites like chlorophyll and carotenoids, remains an area that necessitates extensive research. Therefore, this study aimed to investigate the impact of raising the RZT on the growth, metabolites, elements, and proteins of red leaf lettuce. Lettuce was hydroponically grown in a plant factory with artificial light at four different air temperatures (17, 22, 27, and 30°C) and two treatments with different RZTs. The RZT was raised 3°C above the air temperature in one group, while it was not in the other group. Increasing the RZT 3°C above the air temperature improved plant growth and metabolites, including carotenoids, ascorbic acids, and chlorophyll, in all four air temperature treatments. Moreover, raising the RZT increased Mg, K, Fe, Cu, Se, Rb, amino acids, and total soluble proteins in the leaf tissue at all four air temperatures. These results showed that raising the RZT by 3°C improved plant productivity and the metabolites of the hydroponic lettuce by enhancing nutrient uptake and activating the metabolism in the roots at all four air temperatures. Overall, this research demonstrates that plant growth and metabolites can be improved simultaneously with an increased RZT relative to air temperature. This study serves as a foundation for future research on optimizing RZT in relation to air temperature. Further recommended studies include investigating the differential effects of multiple RZT variations relative to air temperature for increased optimization, examining the effects of RZT during nighttime versus daytime, and exploring the impact of stem heating. This research has the potential to make a valuable contribution to the ongoing growth and progress of the plant factory industry and fundamental advancements in root zone physiology. Overall, this research demonstrates that plant growth and metabolites can be improved simultaneously with an increased RZT relative to air temperature. This study serves as a foundation for future research on optimizing RZT in relation to air temperature. Further recommended studies include investigating the differential effects of multiple RZT variations relative to air temperature for increased optimization, examining the effects of RZT during nighttime versus daytime, and exploring the impact of stem heating. This research has the potential to make a valuable contribution to the ongoing growth and progress of the plant factory industry and fundamental advancements in root zone physiology.

Variations in plant root traits shaped by intraspecific interactions are species-specific

Intraspecific plant interactions are crucial in terrestrial ecosystems, especially in artificially controlled ecosystems. Understanding plant root development can facilitate the manipulation of root traits to enhance the productivity and sustainability of agricultural and pastoral ecosystems. To date, most studies on interactions between the plants have focused on environmental factors or individual species; however, the lack of cross-species comparative analyses has resulted in a significant disparity in findings. In this study, we conducted a greenhouse experiment using five dominant species from alpine grasslands, including three legume species (Thermopsis lanceolata, Oxytropis ochrocephala, and Tibetia himalaica) and two grass species (Elymus nutans and Stipa aliena). Using single-plant cultivation as the control, we investigated the overall changes in plant biomass and root traits when two conspecific plants are grown together (intraspecifically). Simultaneously, we explored the differences in roots traits between the interaction and no-interaction zones. The results showed that, firstly, there was no significant difference in biomass and root traits of different zones when single-planted. But the impact of intraspecific interactions on neighboring plants exhibited significant species-specific. In terms of biomass and root traits (except for forks), E. nutans, T. lanceolata and T. himalaica responded significantly negatively to their neighbors. Whereas S. aliena and O. ochrocephala showed no significant changes and even positive responses. The overall trend of changes in the root zones, whether interactive or non-interactive, was consistent, either increasing or decreasing simultaneously, albeit to different extents. For instance, the difference between the interaction and no-interaction zones of T. lanceolata and O. ochrocephala was substantial, leading to allometric growth. Finally, our results showed poor correlations of physicochemical and nutrient factors with root traits in four of the five species, all except for E. nutans. Altogether, our findings confirmed that root trait variations resulting from intraspecific plant interactions are species-specific. These findings underscored the importance of species-specific in intraspecific plant interactions involving biological interactions among plants, which should be considered in future studies.

A simple method for evaluating the relative water uptake rate of drip‐irrigated crops

AbstractDrip irrigation is widely acknowledged for its water use efficiency, yet evaluating relative water uptake rates (RWURs, ratios between the water uptake rates and the irrigation rates) remains pivotal for effective system design and management. This article presents a novel method employing straightforward measurements of wetted soil surfaces around emitters or perpendicular to driplines, both with and without water uptake, emphasizing simplicity and practicality. The proposed method offers valuable insights into agronomic water use efficiency, facilitating the optimization of drip irrigation for both annual and perennial crops. While effective for intensively irrigated crops, the method does have limitations for smaller wetted areas and longer irrigation cycles, depending also upon a reasonable determination of the active root zone depth and the soil capillary length. Despite relying on a simplified water uptake model, the accessibility and cost‐effectiveness of the method render it a valuable tool for assessing RWURs in diverse agricultural settings, contributing to the sustainable utilization of water resources in drip irrigation.

Continental-scale bias-corrected climate and hydrological projections for Australia

Abstract. The Australian Bureau of Meteorology has developed a national hydrological projections (NHP) service for Australia. The NHP aimed to provide nationally consistent hydrological projections across jurisdictional boundaries to support planning of water-dependent industries. NHP is complementary to those previously produced by federal and state governments, universities, and other organisations for limited geographical domains. The projections comprise an ensemble of application-ready bias-corrected climate model data, derived hydrological projections at daily temporal and 0.05° × 0.05° spatial resolution for the period 1960–2099, and two emission scenarios (Representative Concentration Pathway (RCP) 4.5 and RCP8.5). The spatial resolution of the projections matches that of gridded historical reference data used to perform the bias correction and the Bureau of Meteorology's operational gridded hydrological model. Three bias correction techniques were applied to four CMIP5 global climate models (GCMs), and one method was applied to a regional climate model (RCM) forced by the same four GCMs, resulting in a 16-member ensemble of bias-corrected GCM data for each emission scenario. The bias correction was applied to fields of precipitation, minimum and maximum temperature, downwelling shortwave radiation, and surface winds. These variables are required inputs to the Bureau of Meteorology's landscape water balance hydrological model (AWRA-L), which was forced using the bias-corrected GCM and RCM data to produce a 16-member ensemble of hydrological output. The hydrological output variables include root zone soil moisture (moisture in the top 1 m soil layer), potential evapotranspiration, and runoff. Here we present an overview of the production of the hydrological projections, including GCM selection, bias correction methods and their evaluation, technical aspects of their implementation, and examples of analysis performed to construct the NHP service. The data are publicly available on the National Computing Infrastructure (https://doi.org/10.25914/6130680dc5a51, Bureau of Meteorology, 2021), and a user interface is accessible at https://awo.bom.gov.au/products/projection/ (last access: 24 November 2023).

Effect of Different Nitrogen Levels on Water and Nitrate Distribution in Aeolian Sandy Soil under Drip Irrigation

Understanding the distribution of water and nitrate nitrogen in the soil profile is crucial for the reasonable operation of fertigation, and it is also fundamental for controlling and regulating nitrate nitrogen in the root zone, thereby meeting a crop’s requirements. The application rates of fertilizer and water directly influence this distribution of water and nitrate nitrogen. However, the effects in Aeolian sandy soil, a type of developing soil bordering deserts, remain ambiguous. In this study, field experiments for different drip fertigation treatments in Aeolian sandy soil were conducted to investigate the soil water distribution, as well as that of nitrate nitrogen. A completely randomized experimental design was implemented, encompassing three levels of irrigation amount: low (W1), medium (W2), and high (W3), and three levels of nitrogen application rate: low (F1), medium (F2), high (F3). After the completion of each irrigation treatment, soil samples were extracted at 10–20 cm intervals. The soil water and nitrate nitrogen contents in the profiles of these samples were measured. The experimental results revealed that increasing the nitrogen application rate facilitated the retention of greater amounts of water and nitrate nitrogen in the soil profile. However, with an increase in the nitrogen application rate, both soil water and nitrate nitrogen exhibited a radial tendency to move away from the drip emitter. Some moved upward and accumulated in surface soil near a ridge furrow, while some moved downward and remained in a deeper area approximately 30 cm horizontally from the emitter at depths of 40–60 cm. The uniformity of the water distribution decreased with increasing nitrogen application under low water conditions, with a reversal of this trend observed in medium and high water treatments. The effect of nitrogen application level on the uniformity of the nitrate nitrogen distribution was not significant. There was no significant correlation between the average soil water content and nitrate nitrogen content along the horizontal direction, however, a positive correlation existed in the vertical direction. In the whole profile, increasing the nitrogen application enhanced the correlation under low water conditions, but under medium and high water conditions, this trend was the opposite. This implies that, to avoid nitrate nitrogen leaching or limiting in a specific area, a moderate nitrogen application level is advisable. Under low water conditions, nitrogen application showed a positive effect on the nitrate nitrogen content, and a higher application is recommended. In cases of substantial water irrigation or rainy years, the nitrogen application rate should be decreased.

Localized nitrogen supply facilitates rice yield and nitrogen use efficiency by enabling root-zone nitrogen distribution and root growth

IntroductionLocalized nitrogen (N) supply affects rice N uptake by influencing N release, and few studies have examined the effects of root zone N distribution and root growth on rice yield under localized N supply (LNS).MethodsA two-year field experiment was conducted with six treatments: no N application, farmers’ fertilizer practice (FFP), and four LNS treatments, including two types of N fertilizer with urea (U) and controlled release urea (CRU) were mechanically side deep fertilized (SDF) or root zone fertilized (RZF) at 10 cm soil depth (US, UR, CRUS and CRUR treatments, respectively).ResultsCompared with FFP, the dry matter accumulation, N uptake, and yield of LNS increased by 27%, 21%, and 17%, respectively. For N fertilizer type, compared with U, the NH4+-N concentration, total root surface area, volume, average diameter, and root biomass of CRU were significantly increased by 50%, 43%, 53%, and 23%, respectively, which resulted in a significant increase in yield by 12%. Regarding the N application methods, the total surface area, volume, average diameter, and root biomass of SDF were significantly increased by 32%, 24%, 10%, and 25% compared with RZF, respectively. However, the NH4+-N under RZF was more stable and lasted longer, with a significant increase in NH4+-N concentration of 21% compared to the SDF. Moreover, CRUR increased yield, N agronomic use efficiency, and gross return by 3.15%, 5.62%, and 2.81%, respectively, compared to CRUS.ConclusionCRU should be selected as the recommended N fertilizer types, and the combination of CRU and RZF was the most effective choice for rice production.

Nitrogen use efficiency in bread wheat: Genetic variation and prospects for improvement.

Nitrogen (N) is one of the primary macronutrients required for crop growth and yield. This nutrient is especially limiting wheat yields in the dry and low fertile agro-ecologies having low N in the root zone soil strata. Moreover, majority of farmers in India and South Asia are small to marginal with meagre capacity to invest in costly nitrogen fertilizers. Therefore, there is an immense need to identify lines that use nitrogen efficiently. A set of 50 diverse wheat genotypes consisting of indigenous germplasm lines (05), cultivars released for commercial cultivation (23) and selected elite lines from CIMMYT nurseries (22) were evaluated in an alpha-lattice design with two replications, a six-rowed plot of 2.5m length for 24 agro morphological, physiological and NUE related traits during two consecutive crop seasons in an N-depleted precision field under two different N levels of 50%-N50 (T1) and 100%-N100 (T2) of recommended N, i.e., 100 kg/ha. Analysis of variance revealed significant genetic variation among genotypes for all the traits studied. About 11.36% yield reduction was observed at reduced N levels. Significant correlations among NUE traits and yield component traits were observed which indicated pivotal role of N remobilization to the grain in enhancing yield levels. Among N-insensitive genotypes identified based on their yielding ability at low N levels, UASBW13356, UASBW13358, UASBW13354, UASBW13357 and KRL1-4 showed their inherent genotypic plasticity toward N application. The genotypes with more yield and high to moderate NUtE can be used as parents for the breeding of N efficient genotypes for marginal agro-ecologies. Low N tolerant genotypes identified from the current investigation may be further utilized in the identification of genomic regions responsible for NUE and its deployment in wheat breeding programs. The comprehensive data of 24 traits under different nitrogen levels for diverse genotypes from India and global sources (mainly CIMMYT) should be useful for supporting breeding for NUE and thus will be of great help for small and marginal farmers in India and South Asia.

Time Series Analysis of Nonlinear Head Dynamics Using Synthetic Data Generated with a Variably Saturated Model.

The performance of time series models is assessed using synthetic head series simulated with a numerical model that solves Richards' equation for variably saturated flow. Heads were simulated in a homogeneous unconfined aquifer between two parallel canals; measured daily precipitation and potential evaporation are specified at the land surface and root water uptake is simulated. The head response to a precipitation event is nonlinear and depends on the saturation degree and rainfall before and after the precipitation event while evaporation reduction occurs during summers. Synthetic series were generated for 27 years and three different soil types; the unsaturated zone thickness varies between 0 and >5 m. The synthetic head series were simulated with a linear and nonlinear time series model. Performance of a linear time series model with four parameters, using a scaled Gamma response, gave R2 values ranging from 0.67 to 0.96. The nonlinear time series model with five parameters simulates recharge using a root zone reservoir after which the head response to recharge is simulated with a scaled Gamma response function. The nonlinear time series model was able to simulate all synthetic head series very well with R2 values above 0.9 for almost all models. The head response of the nonlinear model to a single precipitation event compares well to the response of the variably saturated groundwater model. The provided scripts may be used to simulate synthetic head series for other climates or for systems with additional complexity to assess the performance of other data-driven models.

Plant Watering System Using ESP8266

Efficient water management is crucial for sustaining healthy plant growth, especially in environmentsprone to drought or excessive moisture. This paper presents a novel plant watering system designed to optimize water usage while ensuring adequate hydration for plants. The system incorporates sensors to measure soil moisture levelsand environmental conditions, such as temperature and humidity, enabling real-time monitoring and responsive watering. Utilizing a microcontroller-based control unit, the system autonomously regulates watering intervals and durations based on preset thresholds and plant specific requirements. By employing drip irrigation technology, water is delivered directly to the root zone, minimizing waste and promoting efficient absorption. Experimental results demonstrate the system's effectiveness in maintaining optimal soil moisture levels, fostering plant health, and conserving water resources. This innovative approach offers a sustainable solution for automated plant care, suitable for both indoor and outdoor cultivation environments.

Pinus sibirica Du Tour в условиях интродукции на примере Полярно-альпийского ботанического сада-института

The study has been conducted at the Polar-Alpine Botanical Garden-Institute, the northernmost botanical garden in Russia (67°38′ N). The aim of this work has been a comprehensive analysis of the condition of Siberian stone pine trees (Pinus sibirica Du Tour) during their introduction in the Arctic. The condition of 8 specimens of the species cultivated at the experimental plot in the town of Apatity has been examined. Their phenological development has been analyzed: the swelling and breaking of the vegetative buds, the end of the elongation and maturation of the needles, the beginning and end of growth of the annual shoots, the lignification of the shoots, the beginning and end of pollen dispersion. The degree of lignification of the annual shoot, the winter hardiness, the habit, the shootforming capacity, the height increment, the generative development and the reproduction in the plantation have also been assessed. The risk of a tree falling has been determined by considering its surroundings and exposure to wind. The root zones, the butts, the trunks, the crown bases, the boughs and the crowns have been examined for the presence of hollows, cracks, decomposition, fungal fruit bodies, damage, weak forks, dead branches, etc. The application of an approach combining the analysis of seasonal development, viability and risk of tree fall is promising for a comprehensive and objective assessment of the condition of Siberian stone pine trees by morphological and phenological characteristics during the introduction to the Arctic zone of the Russian Federation. The phenological rhythm of the studied trees corresponds to the environmental conditions during the introduction to the Polar-Alpine Botanical Garden-Institute named after N.A. Avrorin. Vegetation begins in late May. By the end of August the annual shoots lignify, which indicates the readiness of the plants for the winter period. The close timing of the onset of phenophases and their low variation may indicate a low dependence of the seasonal development of Siberian stone pine on weather conditions during the introduction to the central part of the Kola Peninsula. The trees are winter-hardy, retain the life form inherent to the species, have a high shoot-forming capacity and annual height increment. They reach the generative stage of development. For their propagation in the plantation, it is necessary to attract seed material from other regions. The trees are monocormic, unimucronate and bimucronate. They are characterized by dense crowns. Their apical and lateral shoots are developed. In rare cases, the increment of lateral shoots is reduced. The V-shaped forks have been noted on the stems and a hollow in the butt area has been found on one of the trees. An additional instrumental examination is needed to determine the effect of diseases or pathogens on the stability of the trees.

Use of the biopore technique to improve soil quality and the growth of beach Casuarina plants on the reclaimed former tin mine land in Bangka Belitung Islands

The tin mining process removes soil layers so that the soil becomes dry and nutrient-poor. Reclamation of tin mining in Selingsing, Gantung Sub-district, Belitung Timur Regency, Bangka Belitung Islands Province has been carried out through revegetation using beach Casuarina plants, but plant growth is slow. On of the efforts that can be made to improve plant growth to restore land and forest conditions is using the biopore technique combined with organic litter and bioactivator solution. This study was therefore aimed to elucidate the effect of the biopore technique on soil quality and the growth of beach Casuarina on the reclaimed former tin mine land. Treatments tested were the use of bamboo biopores and without the use of bamboo biopores, with five replications in each treatment. The effect of variation was measured based on nitrogen, phosphorus, potassium, and lead contents in the root zone and plant growth (plant height and diameter). The results showed that compared to those without biopore treatment, the biopore treatment significantly increased nitrogen, phosphorus, and potassium contents by 0.67%, 2.12%, and 19%, respectively. The organic component of biopore treatment influenced the formation of metal bonds, as indicated by a decrease in lead content by 0.35%. The best plant height of 42 cm was observed in the treatment without biopore, and the best plant diameter of 2.9 cm was in the biopore treatment.

First report of Root-Knot Nematode Meloidogyne enterolobii infecting coriander in Shaanxi, Northern China.

Coriander (Coriandrum sativum), which can be used for its root, stem, and leaf as both food and medicine (Prachayasittikul et al. 2018), is widely cultivated in China. The coriander cultivation area of Guanzhong region, including Xi' an, Xianyang, and Weinan, is 20 million m2, which accounts for 85.7% of the total cultivation area in Shaanxi. In September 2022, obvious galls were observed on the roots of coriander plants (cv. Xiaoye) growing in a field in Huyi District, Xi' an City (34°1'26.4"N, 108°31'58.8"E). The diseased plants did not show obvious above-ground symptoms. To identify the species, second-stage juveniles (J2s) and males were collected from soil in the root zone, and adult females were isolated from galls of diseased roots. The perineal patterns of adult females (n = 20) were round to oval, with high dorsal arches and no obvious lateral lines were observed. Morphological measurements of females (n = 20) included body length (L) = 682 ± 56 (554 to 780) μm, body width (BW) = 522 ± 45 (420 to 597) μm, stylet = 14.9 ± 0.9 (13.4 to 16.3) μm, dorsal pharyngeal gland orifice to stylet base (DGO) = 5.3 ± 0.5 (4.3 to 6.3) μm, vulval slit length = 26 ± 2.8 (20 to 32) μm, vulval slit to anus distance = 21 ± 1.7 (18.5 to 26) μm. Measurements of males (n = 8) were L = 1398 ± 57 (1308 to 1450) μm, BW = 28 ± 2.9 (23 to 32) μm, stylet = 16.1 ± 0.8 (15.3 to 17.3) μm, DGO = 4.5 ± 0.5 (3.5 to 4.9) μm, spicules = 27 ± 1.1 (26 to 29) μm. Measurements of J2s (n = 20) were as follows: L = 434 ± 16.8 (391 to 477) μm, BW = 15.6 ± 0.9 (13.7 to 17.3) μm, stylet = 12.6 ± 0.6 (11.3 to 13.6) μm, DGO = 3.9 ± 0.3 (3.4 to 4.5) μm, tail = 52 ± 4.0 (47 to 60) μm, hyaline tail length = 15.6 ± 1.3 (13.6 to 18.6) μm. These morphological characteristics were consistent with those described for Meloidogyne enterolobii (Yang and Eisenback 1983). Ten females were put in 10 tubes for DNA extraction following Htay et al. (2016). The ITS-rDNA sequence was amplified using the primers 18S/26S (Vrain et al. 1992). A 765 bp fragment was obtained and the sequence (GenBank OR789453) was 99.87% identical to sequences of M. enterolobii (MT406251 and MT067559). The mtDNA CoxII-16S sequence was amplified using primers C2F3/1108 (Powers and Harris, 1993). The sequence was 705 bp (OR795028) and 100% identical to sequences of M. enterolobii (MK455870 and MZ643270). A single 236 bp fragment was amplified using species-specific primers Me-F/Me-R, confirming the species as M. enterolobii (Long et al. 2006). The infection test was conducted in a greenhouse at 27 ± 2℃. Eight 2-week-old coriander plants (cv. Xiaoye) were individually grown in pots filled with sterilizer soil and inoculated with 800 J2s hatched from collected M. enterolobii egg masses. Forty-five days after nematode inoculation, the inoculated plants had galled roots like those observed in the field. The reproduction factor (final population density/initial population density) was 11.9 ± 2.0, indicating coriander was a suitable host for M. enterolobii. No symptoms were observed in controls. To our knowledge, this is the first known natural infection of coriander with M. enterolobii in China. M. enterolobii has been reported on various crops in southern provinces of China (EPPO, 2023). Considering the high level of agricultural trade between different regions, there is a high risk of M. enterolobii transmission to Guanzhong region through infested soil and susceptible plant materials. Further monitoring and research on effective control strategies are needed to prevent the spread of this nematode.

Effects of cold storage duration and root zone temperature on flowering of amaryllis (Hippeastrum striatum ‘Blossom Peacock’)

Effects of cold storage duration and root zone temperature on flowering of amaryllis (Hippeastrum striatum ‘Blossom Peacock’)

Phosphorus Fertilization Can Improve Young Almond Tree Growth in Multiple Replant Settings

Young almond (Prunus amygdalus) orchards replanted where old orchards of stone fruits (Prunus sp.) have been removed are subject to physical, chemical, and biotic stressors. Among biotic challenges, for example, is almond/stone fruit replant disease (ARD; formally known as Prunus replant disease), which specifically suppresses the growth and yields of successive almond and other stone fruit plantings and is caused, in part, by a soil microbial complex. During four orchard trials representing different almond replant practices and scenarios in the San Joaquin Valley in California, we examined the impacts of phosphorus (P) fertilization on the growth of replanted almond. During all trials, P was applied to tree root zones just after replanting, and the impact was assessed according to trunk cross-sectional area (TCSA) growth for 2 years. Expt. 1 was performed where a previous almond orchard was cleared using whole orchard recycling (i.e., the old orchard was “chipped” and then turned into the soil). The land was replanted without preplant soil fumigation. We tested separate fertilizer treatments based on various P, nitrogen, micronutrient, and “complete” formulations. Expt. 2 was also performed where an old almond orchard was recycled, but the soil was preplant-fumigated before replanting. Here, we tested only P fertilization. Expts. 3 and 4 were conducted where an old peach (Prunus persica) orchard was removed. Here, P and nitrogen fertilizer treatments were tested among additional factors, including preplant soil fumigation (Expts. 3, 4) and whole orchard recycling chips (Expt. 4). During all four trials, P fertilization (P at 2.2 to 2.6 oz/tree within a few weeks after planting) significantly increased TCSA growth. The growth benefit was nuanced, however, by almond cultivar, date of replanting, rootstock, and other site-specific factors. Although P fertilization did not match the benefit of preplant soil fumigation for the management of ARD, our data indicated that P fertilization can improve the growth of young almond orchards in diverse replant settings with or without preplant soil fumigation and should be considered by California almond producers as a general best management practice.

The Architecture of a Root Zone of a Large Magmatic Conduit System From High Resolution Magnetic, Gravity and Petrophysical Data: The Reinfjord Ultramafic Complex

AbstractThe Seiland Igneous Province (SIP) is a large province of mafic and ultramafic (UM) complexes interpreted to be relics of a giant plumbing system feeding the Ediacaran Central Iapetus Magmatic Province. The Reinfjord Ultramafic Complex (RUC) is one of the four major ultramafic complexes of the SIP. The RUC has a younger dunite core surrounded by wehrlite and lherzolite embedded in country rocks consisting of layered gabbros with sub‐horizontal layering and metamorphosed sedimentary rocks. Here, we develop a 3D subsurface model for the RUC using high‐resolution magnetic and gravity data and extensive petrophysical measurements from oriented surface samples and drill core samples. Our model indicates that the RUC narrows in depth, extending a minimum of 1.4 km below sea level, and plunges eastwards below the country rock. This model allows us to decipher the lithologic heterogeneities, and the depth and lateral extent of ultramafic rocks, which we interpret in the context of the geologic history of the area. The RUC is spatially separated from other UM complexes of the SIP and the result of this study indicates a smaller depth extent. Combining these findings with the previously reported distribution of the SIP rocks based on the regional gravity data, we propose that the uplift of the crustal block hosting the RUC is larger than for ultramafic complexes in the northwestern part of the SIP.

Effect of root zone heating on cold tolerance of papaya (Carica papaya L.)

ABSTRACT Low-temperatures during winter are a serious problem in the cultivation of tropical fruit trees in temperate regions. The study investigated whether root zone heating treatments could improve cold injury tolerance in papaya. Leaf water potential was −2.22MPa and leaves wilted in the Control, where the root zone was not heated. However, where the root zone was heated to 20°C or only during the daytime, leaf water potentials were −1.31MPa and −1.41MPa, respectively, and no signs of leaf wilting were observed, suggesting that cold wind damage was suppressed unless temperatures fell below freezing. In contrast, where the root zone was heated, leaves wilted rapidly as temperature fell below the freezing point, and all trees had died by 12 January 2018 (72 days of experiment), suggesting that freezing injury could not be controlled by heating the root zone. It is therefore suggested that in addition to root zone heating, heating the greenhouse only on days when the temperature is below the freezing point would also prevent freezing injury. This has the potential to reduce the total greenhouse heating time by 97%. It also has the potential to reduce fuel costs for overwintering papaya, a tropical fruit tree cultivated in a temperate region.

Analysis of PAF and NAF Tests Using NAPP and ANC Methods at Hajak Site, North Barito, Central Borneo

Acid mine drainage (AMD) is a significant challenge for the global coal mining industry, necessitating specialized treatment to prevent its occurrence. A crucial step in AMD prevention is identifying rocks that contribute to its formation. These rocks are classified into Potential Acid-Forming (PAF) rocks and Non-Acid-Forming (NAF) rocks. PAF rocks have the potential to produce acid, while NAF rocks do not. Laboratory analyses, including Maximum Potential Acidity (MPA), Acid Neutralizing Capacity (ANC), Net Acid Producing Potential (NAPP), and Net Acid Generating (NAG) tests, identified 3 sample points with potential PAF characteristics out of 35 samples tested (see Table 3.1). Among these, 2 sample points were classified as Potential Acid Forming-Low Capacity, and 1 sample point was categorized as Potential Acid Forming-Medium Capacity (NAG pH 4.5, NAPP 10 kg H2SO4/ton). The acidity level of mine water resulting from landfilling varies significantly based on the mineral content and landfilling techniques used. Mined material with high carbonate mineral content tends to have lower acidity levels in leachate and can even neutralize formed acid. The stockpiling strategy implemented involves layering PAF material followed by a final cover of NAF material and a rooting zone to mitigate acid formation.