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Canopy rainfall interception is one key hydrological process, affecting rainwater redistribution and effectiveness in semiarid regions. Canopy rainfall interception loss is jointly influenced by meteorology, vegetation and topography. The canopy water storage capacity (S), rainfall interception depth (Im) and ratio (I%) and vegetation characteristics, together with topographic factors of three grassland communities (dominated by Bothriochloa ischaemum, Lespedeza davurica and Artemisia gmelinii, respectively) were investigated on the Loess Plateau of China during the main growing season (June to September). Results showed that Im ranged from 0.55 to 0.89 mm and I% ranged from 6.14% to 12.1%, with the maximum values occurring in August for three communities, and A. gmelinii community had the largest Im (0.89 mm) and I% (12.1%). The Im and I% were positively correlated with aboveground biomass (AGB), coverage (Cov), leaf area index (LAI), community‐weighted mean height (CWMH) and altitude (Alt), but negatively correlated with slope degree and rainfall intensity (RI). Hierarchical partitioning analysis (HPA) showed that AGB had the highest contribution for Im (20.3%), while Alt had the highest contribution for I% (18.2%). The regression models based on forward selection could effectively predict the values of Im (R2 = 0.802, RMSE = 0.049) and I% (R2 = 0.546, RMSE = 1.434). Topographic factors (altitude, slope degree and aspect) indirectly influenced both Im and I% by modulating vegetation characteristics (AGB, Cov, etc.). All these indicated that aboveground biomass mainly determines grassland community rainfall interception loss in the semiarid Loess Plateau. [ABSTRACT FROM AUTHOR]

Quantification of autotrophic (Ra) and heterotrophic (Rh) components of soil respiration (Rs) could greatly improve our understanding of terrestrial carbon cycling. Here, we investigated the effect of nitrogen (N) and phosphorus (P) supply on soil respiration rates and its components, and seasonal cumulative soil CO2 efflux in a semiarid grassland. A two‐factor experiment of N (0, 50 and 100 kg N ha−1 yr−1) and P (0, 18 and 36 kg P ha−1 yr−1) supply was conducted on the Loess Plateau in 2018–2021. Our results indicated that the promoting effect of combination of N and P supply on soil respiration and its components was greater than that of N/P supply alone. N and/or P supply increased the cumulative soil CO2 efflux in both non‐growing and growing seasons, and the non‐growing season CO2 efflux accounted for ∼25% of the growing season CO2 efflux. The increase of cumulative CO2 efflux from Ra in response to N and/or P supply was significantly greater than that of Rh in 2018 and 2019, while it shifted to the opposite, that is, a greater increase in Rh than in Ra in 2020 and 2021. Our results suggest that 100 kg N ha−1 yr−1 supply alone is an optimum fertilization scheme to trade‐off grassland productivity and soil CO2 emissions. Our results highlighted that the promoting effects of N and P fertilization on different soil CO2 efflux components could be reversed in a relatively short period (4 years), and this should be considered when nutrient addition is adapted to restore degraded grasslands. Plain Language Summary: Nitrogen (N) and/or phosphorus (P) addition is a widely‐used restoration measure in global grassland, on the other hand nutrient addition could subsequently alter soil CO2 emissions via directly/indirectly effects on plant root growth and soil microbial activity. Our study quantified the effect of N and/or P supply on soil CO2 emissions from soil respiration and its two components through a 4‐year field experiment. We found that N and/or P supply simultaneously promoted soil respiration initially within 1–2 years after fertilization, although this effect diminished after 3 years of soil nutrient addition. 100 kg N ha−1 yr−1 supply alone is the optimum fertilization amount to tradeoff productivity improvement and soil CO2 emissions in a semiarid grassland. Key Points: N and/or P supply significantly increased soil CO2 emissions from semiarid grasslandsThe cumulative soil CO2 efflux was four times higher in the growing than in the non‐growing seasonThe promoting effect of N and/or P supply on soil CO2 emissions weakened with fertilization duration [ABSTRACT FROM AUTHOR]

It is critical to identify and evaluate efficient phosphate-solubilizing bacteria (PSB) that enable P uptake from unavailable forms, and therefore improve the phosphorus (P) uptake efficiency of crops. The Enterobacter cloacae strain NG-33, belonging to PSB, was isolated and identified from calcareous rhizosphere soils in Nonggang National Reserve, Guangxi, China. The stain NG-33 could reduce the pH of the medium to below 5.6, and had the ability to release soluble phosphorus (P; 180.7 μg ml-1) during the culture in the National Botanical Research Institute's Phosphate medium (NBRIP), and produced such organic acids as gluconic acid (4,881 mg L-1), acetic acid (346 mg L-1), and indole-3-acetic acid (20.4 μg ml-1). It could also convert inorganic P in AlPO4 (Al-P) and FePO4 (Fe-P) into soluble P, with conversion efficiencies of 19.2 μg ml-1 and 16.3 μg ml-1, respectively. Under pot experiments and when compared controls without inoculating NG-33, the shoot and root biomass of maize seedlings showed increases by 140% for shoot biomass and by 97% for root biomass in loamy soil (P sufficient) inoculated with NG-33. In sandy soil (P deficit) supplemented with tricalcium phosphate and inoculated with NG-33, the soluble P content was significantly higher, 58.6% in soil and 33.6% in roots, meanwhile, the biomass of shoots and roots increased by 14.9 and 24.9%, respectively. The growth-promoting effects coupled to the significant increase in leaf net photosynthetic rate and stomatal conductance of plants grown in NG-33-inoculated soil. Inoculating NG-33 could significantly improve the diversity and richness of bacterial population and altered the dominant bacterial population in soil. [ABSTRACT FROM AUTHOR]

Background and aims: High aluminum (Al3+) concentrations associated with subsoil acidity is a major constraint to durum wheat (Triticum turgidum) production as it inhibits root growth affecting crop tolerance to drought. This study evaluated the introgressed TaMATE1B gene on drought resistance and Al3+ toxicity in durum wheat. Methods: Durum wheat lines Jandaroi–TaMATE1B (introgressed with the TaMATE1B gene) and Jandaroi–null (without TaMATE1B gene) were grown in 1-m deep columns filled with re-constructed field soil with Al3+-rich acid subsoil in a glasshouse under well-watered conditions until the onset of ear emergence (Z51), before imposing well-watered and terminal drought treatments. Results: Jandaroi–TaMATE1B produced 25.3 % higher grain yield than Jandaroi–null under well-watered conditions and 49.0 % higher grain yield under terminal drought. Terminal drought reduced grain yield by 47.7 % in Jandaroi–TaMATE1B and 72 % in Jandaroi–null, relative to well-watered conditions. The effects of TaMATE1B on grain yield can be attributed to increased root growth and proliferation below 0.4 m in Al3+-toxic soil. Jandaroi–TaMATE1B had 34.5 and 32.0 % more total root biomass than Jandaroi–null in the well-watered and terminal drought treatments, respectively (P ≤ 0.05). Jandaroi–TaMATE1B had a significantly higher root: shoot ratio than Jandaroi–null at Z51. Introgression of the TaMATE1B gene did not affect grain-filling duration, but terminal drought reduced it by 24 days in both lines. Conclusions: Introgression of the Al3+-tolerant TaMATE1B gene into durum wheat improved terminal drought resistance by enabling root growth and proliferation into deep layers of Al3+-rich acidic soil. [ABSTRACT FROM AUTHOR]