Alleviation of drought stress in Phyllostachys edulis by N and P application

Abstract

The aim of this study was to explore whether nutrition supply can improve the drought tolerance of Moso bamboo under dry conditions. One-year-old seedlings were exposed to two soil water content levels [wellwatered, 70 ± 5% soil-relative-water-content (SRWC) and drought stress, 30 ± 5% SRWC] and four combinations of nitrogen (N) and phosphorus (P) supply (low-N, low-P, LNLP; low-N, high-P, LNHP; high-N, high-P, HNHP; and high-N, low-P, HNLP) for four months. Plant growth, photosynthesis, chlorophyll fluorescence, water use efficiency and cell membrane stability were determined. The results showed that drought stress significantly decreased total biomass, net-photosynthesis (Pn), stomatal-conductance (g_s), leaf-chlorophyll-content (Chl_leaf), PSII-quantum-yield (Φ_PSII), maximum-quantum-yield-of-photosynthesis (Fv/Fm), photochemical-quenching-coefficient (qP), leaf-instantaneous-water-use efficiency (WUE_i), relative-water-content (RWC), photosynthetic-N-use-efficiency (PNUE), and photosynthetic-P-use-efficiency (PPUE). N and P application was found to be effective in enhancing the concentration of leaf N, g_s, and Pn while reducing the production of reactive oxygen species under both water regimes. Under LNHP, HNHP and HNLP treatments, the decreases in total biomass, Pn, Chl_leaf and Fv/Fm of drought-stressed were less evident than the decreases under LNLP. The study suggests that nutrient application has the potential to mitigate the drastic effects of water stress on Moso bamboo by improving photosynthetic rate, water-use efficiency, and increasing of membrane integrity.

Figure 1

Leaf N content per leaf area (N) and leaf P content per leaf area of Moso bamboo under different treatments. Different letters above bars denote statistically significant differences between treatments at the P < 0.05 level according to Tukey’s test. The significance of the factorial analysis (analysis of variance): W, watering effect; N, nitrogen effect; P, phosphorus effect; W × N, watering and nitrogen interaction effect; W × P, watering and phosphorus interaction effect; N × P, nitrogen and phosphorus interaction effect; W × N × P, watering, nitrogen and phosphorus interaction effect. Watering regime [30% (grey bars) or 70% (black bars) of the field capacity] is shown.

Figure 2

Superoxide dismutase (SOD), peroxidase activity (POD) and malondialdehyde (MDA) of Moso bamboo under different treatments. Different letters above bars denote statistically significant differences between treatments at the P < 0.05 level according to Tukey’s test. The significance of the factorial analysis (analysis of variance): W, watering effect; N, nitrogen effect; P, phosphorus effect; W × N, watering and nitrogen interaction effect; W × P, watering and phosphorus interaction effect; N × P, nitrogen and phosphorus interaction effect; W × N × P, watering, nitrogen and phosphorus interaction effect. Watering regime [30% (grey bars) or 70% (black bars) of the field capacity] is shown.