Lei bamboo (Phyllostachys praecox) is an economically viable bamboo species with rich nutrition, a good taste, and a high yield. However, heavy fertilization and covering cultivation are used to produce off-season bamboo shoots, resulting in soil degradation and a decline in site productivity. This study investigated how compound fertilizer decrement and water-soluble humic acid fertilizer application affects soil properties and shoot yield in Lei bamboo plantations of subtropical China. The soil nutrients, enzyme activities, and shoot yield were examined, the bacterial community structure was determined using the high-throughput sequencing method, and their relationships were evaluated under different fertilization treatments: single compound fertilizer and compound fertilizer decrement with water-soluble humic acid fertilizer applications. Compared with those after single compound fertilizer treatments (CF1, CF2), water-soluble humic acid fertilizer addition (CF2HA1, CF2HA2) increased soil organic carbon (SOC), available phosphorus (AP), microbial biomass nitrogen (MBN) contents, the ratio of SOC to total nitrogen (C/N), and sucrase and acid phosphatase (Acp) activities, and decreased alkali hydrolyzed nitrogen (AN) and microbial biomass carbon (MBC) contents. The bacterial community phyla comprised 83.62%–86.16% Proteobacteria, Acidobacteria, Bacteroidetes, Actinobacteria, and Chloroflexi. Water-soluble humic acid fertilizer application also significantly increased yields by over 30%. AP and MBN were important drivers affecting soil bacterial communities, whereas SOC, MBN, and Chloroflexi affected Lei bamboo shoots. Overall, compound fertilizer decrement and water-soluble humic acid fertilizer application shifted the available soil nutrients, sucrase and Acp activity, bacterial community diversity, and shoot yield. An improved understanding of humic acid and the application of humic acid water-soluble fertilizer are of great significance for soil improvement, ecological restoration, and the sustainable management of bamboo forests in the future.

The drought tolerance of plants is significantly influenced by their root architecture traits and root adaptive strategies, but the key root architecture traits that affect drought tolerance and the differences in drought adaptative strategies of species with varying root architectures are not yet clear. This study aimed to investigate the response of three species’ roots to drought and evaluate the key root architecture traits affecting the drought tolerance of the three species. One-year-old potted seedlings of three species [Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.), masson pine (Pinus massoniana (Lamb.)), and moso bamboo (Phyllostachys edulis (Carr.) H. de Lehaie f. edulis)] were planted in a greenhouse under three drought conditions (sufficient water supply, moderate drought, and severe drought) for 90 days. Biomass, root morphology [root surface area (RSA), root length (RL), root diameter (RD)], root architecture [root topological index (TI), fractal dimension (FD), and root branching angle (RBA)] of seedlings were measured monthly. The drought tolerance of species was quantified by studying the response ratio (RR) of root length and biomass in response to drought. We found that: (i) different levels of drought inhibited the biomass accumulation and root growth of the three species, and drought tolerance showed a decreasing order as pine > Chinese fir > bamboo; (ii) drought decreased the RD in bamboo but increased it in pine. Both bamboo and Chinese fir reduced their FD and RBA under drought stress, while pine was relatively stable. All the three species’ roots tended to develop a herringbone branching architecture (increase their TI) under drought stress; (iii) both TI and FD were negatively correlated with the drought tolerance of the seedlings. Our results indicated that plants could adapt to drought by different strategies such as adjusting biomass allocation and root morphology, reducing root branch strength, and branching angles. Roots with narrower branching angles, greater branching complexity, larger TI, and consuming higher cost are more drought-tolerant.

The root of Moso bamboo (Phyllostachys edulis (Carrière) J. Houz.) develops extremely rapidly at seedling phase and is highly sensitive to water content in soil, but its response patterns and adaptation strategies of its root to drought are little known. The aim of this study was to investigate the response of root morphology and architecture of Moso bamboo to drought at seedling phase and then to explore the drought adaptation strategies of its root. One-year-old potted seedlings of Moso bamboo were planted under three drought treatments (control, moderate drought and severe drought) for three months. Seedling growth, specific root length (SRL), root architecture (fractal dimension (FD), root branching angle (RBA) and root topological index (TI)) and non-structural carbohydrate (NSC) concentrations in roots were measured every month. The results are as follows: (i) The dry weight of root and shoot decreased significantly under drought stress. (ii) The SRL decreased under drought stress in the early duration (the first month), and then increased in the late duration (the third month). Both FD and RBA decreased, while TI and the concentrations of NSCs increased under drought stress. (iii) The NSC concentrations were positively correlated with SRL and TI, but exhibited an inverse relationship to FD and RBA. Our results indicated that Moso bamboo seedlings formed a “steeper, simpler, expensive (low SRL and high TI)” root architecture to adapt to a short-term drought (one month), and formed a “cheaper (high SRL)” root to adapt to a long-term drought (three months). Increase of NSC concentrations supported the root architecture plasticity to some extent.

Lei bamboo (Phyllostachys violascens ‘Prevernalis’) has high economic value, providing high yields of quality of bamboo shoots. Heavy use of chemical fertilizers and cover cultivation to produce off-season bamboo shoots results in soil degradation and a decline in soil productivity. This paper introduces an amino acid fertilizer, fish protein fertilizer, to replace a portion of chemical fertilizer, investigating the effects of different fertilizer combinations on bamboo growth, shoot yield, and soil properties, clarifying the growth-promoting mechanism of amino acid fertilizer. Results showed that after replacing 45 kg of compound fertilizer with 10 kg and 20 kg, respectively, of fish protein fertilizer (1) bamboo shoot yield increased by 23.24% and 26.19%, respectively; (2) leaf and root growth were enhanced, thick root proportion increased, and topsoil root proportion decreased; (3) soil pH, contents of available phosphate, soil organic carbon, microbial biomass carbon and microbial biomass nitrogen, soil enzyme activity increased; (4) the contents of nitrogen (N) and phosphate (P) in leaves increased, while the N/P and K/P decreased. Overall, amino acid fertilizer can promote microbial growth through supplying carbon sources and nitrogen sources, enhance soil enzyme activity, thus promote phosphorus activation and increase soil phosphorus effectiveness, and then expand the scale of root foraging and ultimately improve nutrients absorption and increase bamboo shoot yield.

Previous studies have shown that biochar fertilization has profound effects on plant and fine root growth, but there is a lack of studies on how changes in plant and soil stoichiometry by biochar fertilization influence plant growth and root morphology. We investigated the effects of biochar fertilization on biomass, root morphology, plant nutrient concentrations, and the stoichiometry of plants and soil in a greenhouse experiment with Pinus massoniana (Lamb.) (PM) and Cunninghamia lanceolata (Lamb.) Hook. (CL) throughout the 2017 growing season immediately following biochar fertilization application. Four levels of biochar treatment were used, i.e., addition rates of 0 (control), 5 (low biochar), 10 (medium biochar), and 20 t ha⁻¹ (high biochar). Biochar fertilization had no effect on biomass, fine root length, or fine root surface area. Biochar treatment, however, had significant effects on nutrient levels and their stoichiometry in both plants and soil. Detrended correspondence analysis suggested that increases in soil C:N, soil C:P, and soil N:P were associated with increases in plant nutrient levels, especially P concentration. Our results indicate that biochar fertilization prioritizes enhancing plant and soil nutrients over increasing height and diameter in the first growing season. A higher biochar fertilization dosage has a major influence on root morphology for PM and on P concentrations in the plant and soil for CL, probably through different growth characteristics and nutrient resorption rates. Further studies, particularly those considering long-term effects, are necessary before general recommendations regarding biochar application should be given.

Leaf nitrogen (N) and phosphorus (P) stoichiometry at a large geographical scale is the result of long-term adaptation to the environment. Therefore, the patterns of leaf N and P spatial distributions and their controlling factors represent an important issue in current ecological research. To explore the leaf stoichiometry of Chinese fir at a national level, we conducted a meta-analysis based on the dataset of the leaf nitrogen (N) and phosphorus (P) concentrations and the N:P ratio from 28 study sites across China. For all of the age groups considered, the average concentrations of the leaf N and P concentrations and the N:P ratio were 11.94 mg g⁻¹, 1.04 mg g⁻¹, and 12.93, respectively. Significant differences were found in the leaf P concentration and N:P ratio between the five age groups, while the differences in the leaf N concentration between the groups were not significant. Linear fitting results indicated that the leaf P concentration decreased, and the leaf N:P ratio increased with the increase of the MAT (mean annual temperature) and soil N concentration. Redundancy analysis (RDA) revealed that the first axis, with an explanatory quantity of 0.350, indicated that the MAT (mean annual temperature), soil nitrogen concentration and stand age had a good relationship with the leaf P concentration and N:P ratio, while the second axis, with an explanatory quantity of 0.058, indicated that the leaf N concentration was less affected by the environmental factors. These results demonstrate that the leaf P concentration and N:P ratio are affected by the stand age, an uneven distribution of the heat and soil nutrient concentration status, and N, as the limiting element, remaining relatively stable. Overall, our findings revealed the response of leaf stoichiometric traits to environment change, which benefits the management of Chinese fir plantations.