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A pot experiment was carried out to determine the effect of Serendipita indica on the salt response of Lolium multiflorum Lam. Although the salinity decreased the root colonisation of S. indica by 28.34%, successful colonisation of S. indica increased the seed germination rate, fresh weight, leaf relative water content and chlorophyll content by 28.09, 59.01, 38.78 and 28.80%, respectively, compared with uncolonised seedlings. Under salinity, leaf malondialdehyde content, leaf relative electrical conductivity, as well as Na+ content and Na+/K+ ratio in leaves and roots of S. indica-colonised seedlings were decreased by 33.99, 33.31, 63.40% and 47.42, 85.66 and 55.88%, respectively, compared with uncolonised seedlings. Meanwhile, compared with uncolonised seedlings under salinity, the contents of proline in leaves, N, P and K+ in leaves and roots of the S. indica-colonised seedlings were increased by 47.47, 45.69 and 30.05%, and 41.77, 19.51, 19.18 and 155.00%, respectively. These results indicate that S. indica colonisation confers salt tolerance in L. multiflorum seedlings by enhancing osmotic adjustment via actively accumulating proline and K+, increasing the uptake of nutrients such as N and P, and improving Na+/K+ homoeostasis. The study would provide a new idea for the combined application of salt-tolerant plants and symbiotic microorganisms in the ecological restoration of saline-alkali lands.

Our study comparative analyzed the morphological and physiological performance of Juglans regia L. cv. 'Xiangling' (JRX) grafted onto five rootstock species originated from China. A wide range of coefficient of variation (CV), 1.155-39.848%, was detected for fourteen indexes among the studied seedlings. CV of plant height, total dry biomass, total leaf area, root/shoot ratio, chlorophyll index, and stomatal conductance was higher than 15.00%, suggesting higher variation. Principal component analysis, hierarchical cluster analysis and subordinate function analysis were used to screen engrafted seedlings for their quality. All three methods produced the same result that seedling quality of 'Xiangling' engrafted with the five rootstock species from high to low were - Juglans regia L. cv. 'Jizhaomian' (JRJ), JRX, Juglans regia L. cv. 'Lvxiang' (JRL), Juglans mandshurica, Maxim., and Juglans hopeiensis Hu.. The evaluation results were highly consistent with the actual growth performance of the engrafted seedlings, it verified the reliability of our results and the evaluation methods. The results demonstrated that JRJ, JRX, and JRL are potential rootstock candidates in the studied walnut planting regions. It would provide important implication for the selection of proper rootstock species for a certain particular walnut variety.

Abstract Objective Despite controversy over its origin and definition, the significance of tumour deposit (TD) has been underestimated in the tumour node metastasis (TNM) staging system for colon cancer, especially in stage III patients. We aimed to further confirm the prognostic value of TD in stage III colon cancer and to establish a more accurate ‘coN’ staging system combining TD and lymph node metastasis (LNM). Methods Information on stage III colon cancer patients with a definite TD status was retrospectively collected from the Surveillance, Epidemiology and End Results (SEER) database between 2010 and 2017. The effect of TD on prognosis was estimated using Cox regression analysis. Maximally selected rank statistics were used to select the optimal cut‐off value of TD counts. The predictive power of conventional N staging and the new coN staging was evaluated and compared by Akaike's information criterion (AIC), Harrell's concordance index (C‐index) and time‐dependent receiver operating characteristic (ROC) curves. Clinicopathological data of stage III colon cancer patients in the Xiangya database from 2014 to 2018 were collected to validate the coN staging system. Results A total of 39,185 patients with stage III colon cancer were included in our study: 38,446 in the SEER cohort and 739 in the Xiangya cohort. The incidence of TD in stage III colon cancer was approximately 30% (26% in SEER and 30% in the Xiangya database). TD was significantly associated with poorer overall survival (OS) (HR = 1.37, 95% CI 1.31–1.44, p

Plant growth-promoting rhizobacteria (PGPR) can promote plant growth and induce systemic resistance to biological and abiotic stresses. However, do all PGPR have significant effects in arid environments, and which PGPR have the most optimal effects? This study used a pot experiment to investigate the effects of inoculation with two different PGPR on the physiological and ecological characteristics of walnut (Juglans regia) seedlings under drought stress: Bacillus subtilis GE1, which secretes protease only, and Pseudomonas brassicacearum X123, which secretes protease and indoleacetic acid (IAA). The leaves inoculated with X123 under drought stress had higher net photosynthetic rate (Pn), transpiration rate (Tr), and stomatal conductance (gs), especially stomatal length and stomatal width, compared to GE1 inoculation under drought stress. Moreover, inoculation with X123 significantly increased the leaf superoxide dismutase (SOD) and ascorbate peroxidase (APX) activities by 20.84% and 12.41%, respectively, and the gibberellin (GA) and zeatin (ZT) contents by 72.07% and 19.17%, respectively, whereas the leaf soluble sugar and soluble protein contents significantly decreased compared with GE1 inoculation. These results indicated that the effects of GE1 inoculation on the physiological and ecological characteristics of walnut seedling leaves were significantly weaker in comparison with X123 inoculation as a result of its functional characteristics. The application of different PGPR on the drought tolerance of J. regia showed significant differences. Therefore, the selection of appropriate PGPR is key to achieving positive treatment effects under drought conditions.

Abstract Comparative evaluations were conducted to assess the effects of different pH levels, NaCl-induced salt stress, and PEG-induced drought stress on the mycelial growth of Xerocomus badius. The results showed that X. badius mycelium grew well at a wide pH range of 5.00 ~ 9.00. Although the mycelium remained viable, mycelial growth of X. badius was significantly inhibited with increasing salt and drought stresses. Furthermore, a soilless experiment in Petri dishes was performed to investigate the potential of X. badius to induce beneficial effects on seed germination and seedling growth of annual ryegrass (Lolium multiflorum Lam.) under salt and drought stresses. Seed priming with X. badius enhanced the seedling growth of L. multiflorum Lam. under NaCl-induced salt stress and PEG-induced drought stress. However, X. badius did not significantly improve the seed germination under non-stress and mild stress conditions. It suggested that X. badius inoculation with seeds was not essential for seed germination under non-stress and mild stress conditions, but contributed highly to seedling growth under severe stress conditions. Therefore, seed priming with X. badius on ryegrass could be an effective approach to enhance plant tolerance against drought and salt stresses. X. badius could be a good candidate for the inoculation of ectomycorrhizal plants cultivation programs in mild saline and semiarid areas.

Drought is one of the most brutal environmental factors limiting the productivity of fruit trees. The search for new and efficient microorganisms from unexplored environments that can be used to mitigate the negative effects of water stress is an interesting alternative to alleviate the drought stress experienced by plants. This study aimed to determine the effects of PGPR inoculation on the growth and physioecological characteristics of walnut (Juglans regia) seedlings under drought stress. A pot experiment was conducted using J. regia seedlings with controlled water supplies at different levels (light, moderate, and severe drought stress and control) and with or without inoculation with Bacillus cereus L90, a type of PGPR that produces high levels of cytokinins and indoleacetic acid (IAA). Under well-watered conditions, there was no obvious effect of PGPR inoculation on the antioxidant enzyme activities, osmotic adjustment levels, and photosynthetic characteristics of J. regia. As the stress intensity increased, B. cereus inoculation increased the antioxidant enzyme activities in walnut seedlings and changed their photosynthetic characteristics. However, levels of osmotic adjustment substances were decreased as a result of PGPR inoculation. Regardless of water status, B. cereus inoculation induced a significant increase in IAA, gibberellins, and zeatin contents in J. regia. Under well-watered and light stress conditions, the abscisic acid content of walnut was significantly increased by B. cereus inoculation. Additionally, B. cereus inoculation significantly promoted the growth of plants in terms of ground diameter and plant height. As a result, PGPR inoculation could improve the drought resistance of J. regia and improve its photosynthetic characteristics and growth, suggesting that it is a useful supplementary measure for use in afforestation in arid and semiarid environments.

Abstract Plant growth-promoting rhizobacteria (PGPR) are beneficial bacteria that survive within the range of plant rhizosphere and can promote plant growth. The effects of PGPR in promoting plant growth, activating soil nutrients, reducing fertilizer application, and improving the resistance of plant inducible system have been widely investigated. However, few studies have investigated PGPR as elicitors of tolerance to abiotic stresses, especially drought stress. In this study, the effects of Acinetobacter calcoaceticus X128 on the photosynthetic rate (P n), stomatal conductance (G s), intracellular CO2 concentration (C i), and total chlorophyll content [Chl(a+b)] of Sambucus williamsii Hance seedling leaves under moderate drought stress and drought-rewatering conditions were determined. Compared with those of uninoculated seedlings, the average P n values during the entire drought stress of inoculated seedlings increased by 12.99%. As the drought duration was lengthened, C i of uninoculated leaves continued to increase after rapidly declining, whereas G s continuously decreased. Furthermore, their photosynthetic properties were simultaneously restricted by stomatal and non-stomatal factors. After X128 inoculation, C i and G s of S. williamsii Hance leaves continued to decrease, and their photosynthetic properties were mainly restricted by stomatal factors. At the end of the drought stress, water stress reduced [Chl(a + b)] of S. williamsii Hance leaves by 13.49%. However, X128 inoculation decreased this deficit to only 7.39%. After water supply was recovered, P n, G s , and [Chl(a+b)] in uninoculated leaves were reduced by 14.23%, 12.02%, and 5.86%, respectively, relative to those under well-watered conditions. However, C i increased by 6.48%. Compared with those of uninoculated seedlings, P n, G s , and [Chl(a+b)] in X128-inoculated seedlings were increased by 9.83%, 9.30%, and 6.85%, respectively. Therefore, the inoculation of X128 under arid environments can mitigate the reduction of chlorophyll, delay the restriction caused by non-stomatal factors to P n in plant leaves under water stress, and can be more conducive to the recovery of photosynthetic functions of leaves after water supply is recovered.

Abstract In this study, a pot experiment was carried out in greenhouse to investigate the potentials of Xerocomus badius and Serendipita indica to penetrate and colonize roots of ryegrass (Lolium multiflorum Lam.) and to induce beneficial effects on seed germination and seedling growth. The results showed that X. badius and S. indica successfully colonized in the root system of L. multiflorum seedlings and the root colonization rate was 72.65% and 88.42%, respectively. By microscopy, the hyphae, chlamydospores and spores produced by S. indica were observed in roots cortex of L. multiflorum seedlings. In comparison with the non-inoculated seedlings, seedlings inoculated with X. badius and S. indica showed significant increase in growth parameters with plant height, basal diameter, biomass accumulation, relative growth rate, leaf relative water content and chlorophyll content. Also, we found that seedlings inoculated with S. indica exhibited a greater growth-promotion as compared with X. badius-inoculated seedlings. No significant influence of the two fungus application has been observed with respect to seed germination. It suggested that well establishments of mutualistic symbiosis between L. multiflorum and X. badius or S. indica were not so essential to seed germination but contributed highly to the survival and growth of the seedlings.

The issue of how to alleviate the negative effects imposed by water stress is an interesting problem. Plant growth-promoting rhizobacteria (PGPR) colonize the rhizosphere of plants and are known to promote the growth of crops. However, there are few studies characterizing the physiological response of plants to drought stress after PGPR inoculation. The aim of this study was to investigate the effectiveness of different PGPRs in arid environments and then investigated the effects of PGPR inoculation under drought stress on the physiological characteristics and growth of North China red elder (Sambucus williamsii) nursery container seedlings. The viable count of different PGPRs under drought stress varies widely, and the drought tolerance of Acinetobacter calcoaceticus X128 was significantly higher than that of other PGPRs. In comparison with non-inoculation, inoculation with X128 in an arid environment significantly increased stomatal conductance and mitigated the inhibition of net photosynthetic rate caused by drought stress; this mitigating effect of inoculation is enhanced as the level of drought stress increases. Relative to non-inoculated seedlings, cytokinin levels in the leaves increased by 91.17% under severe drought stress conditions in inoculated seedlings. However, X128 inoculation decreased this deficit to only 44.54%. Compared with non-inoculated seedlings, the relative water content of inoculated seedlings under severe drought stress increased by 15.06%, however the relative conductivity decreased by 12.48%. Consequently, X128 could increase dry matter accumulation of S. williamsii regardless of watering status, indicative of the greater benefits of PGPR on shoot growth than root. Therefore, inoculation of A. calcoaceticus X128 under drought conditions play a significant role for alleviating the negative effects imposed by water stress and promoting plant growth.

A pot experiment was carried out to determine the effect of Serendipita indica on the salt response of Lolium multiflorum Lam. Although the salinity decreased the root colonisation of S. indica by 28.34%, successful colonisation of S. indica increased the seed germination rate, fresh weight, leaf relative water content and chlorophyll content by 28.09, 59.01, 38.78 and 28.80%, respectively, compared with uncolonised seedlings. Under salinity, leaf malondialdehyde content, leaf relative electrical conductivity, as well as Na+ content and Na+/K+ ratio in leaves and roots of S. indica-colonised seedlings were decreased by 33.99, 33.31, 63.40% and 47.42, 85.66 and 55.88%, respectively, compared with uncolonised seedlings. Meanwhile, compared with uncolonised seedlings under salinity, the contents of proline in leaves, N, P and K+ in leaves and roots of the S. indica-colonised seedlings were increased by 47.47, 45.69 and 30.05%, and 41.77, 19.51, 19.18 and 155.00%, respectively. These results indicate that S. indica colonisation confers salt tolerance in L. multiflorum seedlings by enhancing osmotic adjustment via actively accumulating proline and K+, increasing the uptake of nutrients such as N and P, and improving Na+/K+ homoeostasis. The study would provide a new idea for the combined application of salt-tolerant plants and symbiotic microorganisms in the ecological restoration of saline-alkali lands. [ABSTRACT FROM AUTHOR]

In order to explore the soil nutrient characteristics and put forward the improvement measures, a field experiment was arranged and performed. The experiment was conducted to evaluate the pH value and primary nutrient status in blueberry garden soil by means of collecting 21 soil samples from the main production base of blueberries in Qingdao, according to the specific requirements of blueberries for soil pH and organic matter arid the second national soil survey nutrient classification standard. Results showed that the blueberry garden soil had the following characteristics: acidic soil, low organic matter content with significant differences among different bases, moderate total nitrogen and alkaline hydrolysis nitrogen contents, high available phosphorus content and above moderate available potassium content. Then, it is found that the primary causes were the differences in soil basic fertility, excessive use of sulfur, inadequate inputs of organic matter, not thorough soil improvement, and imperfect fertilizer management in the blueberry gardens. Finally, the corresponding improvement measures were put forward, for example, increasing organic fertilizer and organic matter covering, as well as the application of CaCO3 and formulated fertilization. [ABSTRACT FROM AUTHOR]