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Understanding how concentrations of elements and their stoichiometry change with plant growth and age is critical for predicting plant community responses to environmental change. We used long-term field experiments to explore how the leaf, stem and root carbon (C), nitrogen (N) and phosphorous (P) concentrations and their stoichiometry changed with growth and stand age in a L. principis-rupprechtii Mayr. plantation from 2012–2015 in the Qinling Mountains, China. Our results showed that the C, N and P concentrations and stoichiometric ratios in different tissues of larch stands were affected by stand age, organ type and sampling month and displayed multiple correlations with increased stand age in different growing seasons. Generally, leaf C and N concentrations were greatest in the fast-growing season, but leaf P concentrations were greatest in the early growing season. However, no clear seasonal tendencies in the stem and root C, N and P concentrations were observed with growth. In contrast to N and P, few differences were found in organ-specific C concentrations. Leaf N:P was greatest in the fast-growing season, while C:N and C:P were greatest in the late-growing season. No clear variations were observed in stem and root C:N, C:P and N:P throughout the entire growing season, but leaf N:P was less than 14, suggesting that the growth of larch stands was limited by N in our study region. Compared to global plant element concentrations and stoichiometry, the leaves of larch stands had higher C, P, C:N and C:P but lower N and N:P, and the roots had greater P and C:N but lower N, C:P and N:P. Our study provides baseline information for describing the changes in nutritional elements with plant growth, which will facilitates plantation forest management and restoration, and makes a valuable contribution to the global data pool on leaf nutrition and stoichiometry.

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BACKGROUND Limited and erratic precipitation with inefficient irrigation scheduling often leads to an unstable crop yield and low water‐use efficiency (WUE) in semi‐arid and semi‐humid regions. A 2‐year field experiment was conducted to evaluate the effect of three irrigation strategies (conventional irrigation (CK), full‐drip irrigation (FI), based on crop evapotranspiration and precipitation forecast, and deficit drip irrigation (DI) (75% FI)) on photosynthetic characteristics, leaf‐to‐air temperature difference (∆T), grain yield, and the WUE of summer maize. RESULTS The results showed that the daily average net photosynthetic rate (Pn) of DI and FI increased by 25.4% and 25.8% at jointing stage in 2018, and 26.3% and 26.5% at grain‐filling stage in 2019 compared with CK, respectively. At jointing stage in 2018 and grain‐filling stage in 2019, the transpiration rate (Tr) of DI was significantly lower than that of FI (P < 0.05) but there was insignificant difference in Pn value (P > 0.05). The ∆T between 12:00–14:00 of DI and FI was significantly lower than that of CK at jointing stage in 2018 and grain‐filling stage in 2019 (P < 0.05). The 2‐year average grain yields of DI and FI were 11.4 and 11.5 t ha−1, which increased by 32.4% and 32.8% compared with CK, respectively. The WUE of DI was 2.82 kg m−3, which was 17.9% and 33.8% higher than that of FI and CK, respectively. CONCLUSION Deficit drip irrigation based on crop evapotranspiration and precipitation forecast improves crop WUE and maintains high grain yields in semi‐arid and semi‐humid regions. © 2021 Society of Chemical Industry.