Effects of different soil moisture on the growth, quality, and root rot disease of organic Panax notoginseng cultivated under pine forests

Incidence and Severity Distribution of Sweet Cherry (Prunus avium) and Their Influencing Factors in Southwest China

Root rot disease is a significant constraint to sweet cherry production in the highlands of southwest China, causing substantial yield losses. While the disease is prevalent, the complex interplay of climate, topography, soil, and management practices on its development remains poorly understood. To address this knowledge gap, a field survey encompassing 95 field sites was conducted to assess disease incidence (DI) and canopy damage index (CDI). Our results showed that the average DI and CDI were 27.04 and 20.52%, respectively. DI and CDI were influenced by management practices: they both increased with the number of planting years and were lower with Cerasus szechuanica rootstock and composted animal manures compared with Da-qingye rootstock and uncomposted animal manures. Climatic and topographic factors also played an important role in observing higher DI at higher altitudes and shady slopes (P < 0.05). Moreover, both DI and CDI demonstrated positive correlations with the aridity index and sunshine duration and negative correlations with mean annual temperature and mean annual precipitation (P < 0.05). Soil properties, including moisture content, bulk density, pH, and sand content, were positively associated with DI and CDI, while clay content and available potassium exhibited negative correlation. The present study emphasizes the combined impact of multiple factors on root rot disease in sweet cherry, with management practices and soil properties having a more decisive effect than climate and topography. These findings provide crucial insights for developing effective disease management strategies.

Effect of Pseudomonas protegens EMM-1 Against Rhizopus oryzae in Interactions with Mexican Autochthonous Red Maize

In the present study, the strain Rhizopus oryzae EMM was isolated from germinated autochthonous red maize seeds, which were harvested in a region of San Diego-Buenavista, Papalotla, Tlaxcala, Mexico, where cobs with fungal infections have been observed. This fungal strain caused wilting in the maize seedlings. Pseudomonas protegens EMM-1 was tested for its ability to inhibit R. oryzae EMM, both in culture media and in association with maize plantlets. P. protegens EMM-1 inhibited the growth of R. oryzae EMM under all culture media conditions explored. The ability of P. protegens EMM-1 to inhibit the growth of R. oryzae EMM associated with plants was evaluated in both a hydroponic system and in vermiculite. In both systems, P. protegens EMM-1 strongly inhibited the growth of R. oryzae EMM. The dry weight of root plants infected with R. oryzae EMM and inoculated with P. protegens EMM-1 increased to 0.43 g, while that of plants infected only with R. oryzae EMM reached just 0.19 g under hydroponic conditions. However, no differences were observed under vermiculite conditions. The dry weight of the aerial region of plants infected with R. oryzae EMM and inoculated with P. protegens EMM-1 was greater than that of plants infected only with R. oryzae EMM, both under hydroponic and vermiculite conditions. These results indicate that P. protegens EMM-1 inhibits the infection caused by R. oryzae EMM, thereby improving plant growth. Moreover, the genome analysis of P. protegens EMM-1 revealed the presence of several genes that potentially encode for antimicrobial compounds, which could strengthen the potential use of P. protegens EMM-1 as a biocontrol agent in maize plants.

Effects of irrigation frequency on root growth, nutrients accumulation, yield, and water use efficiency of Panax notoginseng under micro-sprinkler irrigation

Micro-sprinkler irrigation has been a promising irrigation method to promote Panax notoginseng (Burk) F. H. Chen production but their scientific irrigation frequency in improving yield and water use efficiency of P. notoginseng remains contradictory and inconclusive. The objective of this study was therefore to examine and propose a scientific irrigation frequency in water management of P. notoginseng cultivation considering their impact on soil water, soil available nutrients, root growth, yield, and water use efficiency (WUE). The micro-sprinkler irrigation experiment under shading and rain-shelter conditions was carried out in the growing season of P. notoginseng from 2017 to 2018.The treatments included four micro-sprinkler irrigation frequencies, such as IF1 (irrigation once every three days), IF2 (irrigation once every five days), IF3 (irrigation once every seven days), and IF4 (irrigation once every nine days) in 2017-2018. The results indicated that the IF3 treatment significantly increased the nitrogen accumulation of P. notoginseng (271.98 mg plant-1). In addition, the IF2 treatment enhanced the phosphorus accumulation (27.82 mg plant-1), potassium accumulation (408.38 mg plant-1), total root surface area (67.49 cm2 plant-1), total root volume (3.79 cm3 plant-1) and yield (702 kg ha-1). The IF2 treatment significantly increased WUE by 29.2%, 28.1%, and 37.7% compared with the IF1, IF3, and IF4 treatments, respectively. Our findings suggested that IF2 treatment increased the soil water content, reduced the soil nutrient content, increased the accumulation of phosphorus and potassium in P. notoginseng, promoted the root growth of P. notoginseng, and improved the quality and yield of P. notoginseng, providing a scientific theoretical basis for reasonable water control and green quality production in the cultivation of P. notoginseng under shade and rain shelter cultivation.

Unraveling the Rhubarb (Rheum officinale Baill.) Root and Rhizosphere Microbial Communities in Response to Pathogen Exposure

This study investigated the microbial community composition and structure in healthy and diseased rhubarb (Rheum rhabarbarum) root systems, examining both root tissue and rhizosphere environments. Alpha diversity analysis revealed significantly higher microbial abundance in the rhizosphere compared to root tissues, with notable differences between healthy and diseased plants. Principal coordinate analysis demonstrated that bacterial community composition was primarily influenced by ecological niches (47.5% variation explained), whereas fungal communities segregated based on plant health status. Network analysis revealed increased bacterial community complexity in diseased plants rhizosphere (579 nodes, 13,016 edges) compared to healthy plants (542 nodes, 8700 edges), while fungal networks showed opposite trends with significant reduction in diseased conditions (147 nodes, 30 edges vs. 205 nodes, 418 edges). Correlation analysis identified significant associations between specific microbial taxa and soil properties, with notable positive correlations between certain bacteria (Oscillospirales) and fungi (Barnettozyma, Mortierella) with soil organic matter and nutrient availability. Pathogenic taxa, including Fusarium and members of Burkholderiales, showed negative correlations with beneficial microorganisms, suggesting potential antagonistic relationships. These findings provide crucial insights into the complex interactions within the rhubarb root microbiome and their implications for plant health, contributing to our understanding of root rot disease dynamics and potential management strategies.

Comparison, validation and improvement of empirical soil moisture models for conditions in Colombia

Modeling soil moisture as a function of meteorological data is necessary for agricultural applications, including irrigation scheduling. In this study, empirical water balance models and empirical compartment models are assessed for estimating soil moisture, for three locations in Colombia. The daily precipitation and average, maximum and minimum air temperatures are the input variables. In the water balance type models, the evapotranspiration term is based on the Hargreaves model, whereas the runoff and percolation terms are functions of precipitation and soil moisture. The models are calibrated using field data from each location. The main contributions compared to closely related studies are: i) the proposal of three models, formulated by combining an empirical water balance model with modifications in the precipitation, runoff, percolation and evapotranspiration terms, using functions recently proposed in the current literature and incorporating new modifications to these terms; ii) the assessment of the effect of model parameters on the fitting quality and determination of the parameters with higher effects; iii) the comparison of the proposed empirical models with recent empirical models from the literature in terms of the combination of fitting accuracy and number of parameters through the Akaike Information Criterion (AIC), and also the Nash-Sutcliffe (NS) coefficient and the root mean square error. The best models described soil moisture with an NS efficiency higher than 0.8. No single model achieved the highest performance for the three locations.