Biochar amendment to soil has the potential to improve soil quality and increase crop yield. Arbuscular mycorrhizal fungi (AMF) provide beneficial plant services of stress alleviation with respect to phosphorus (P) deficiency and drought. The aim of this study was to explore interactive effects of biochar with AMF, P fertilization levels and irrigation strategies on growth of potato plants. Potato plants were amended with wood biochar of 0.74 % w/w (B+) or not (BÀ), fertilized with phosphorus of 0.11 mg P g À1 soil (P1) or not (P0), irrigated with full irrigation (FI) or partial root-zone drying irrigation (PRD) and inoculated with AMF of Rhizophagus irregularis (M+) or not (MÀ) in split-root pots in a sandy loam soil. Plants were analysed for growth performance, P and nitrogen (N) uptake and water use efficiency (WUE). Biochar adsorption of mineral P and N in aqueous solution was tested in subexperiment. B+ significantly decreased plant biomass production except under P0 FI MÀ, where B+ increased plant biomass. This growth stimulation was counteracted by treatments of P1, PRD and M+. B+ significantly decreased plant leaf area, P and N uptake and WUE, but had no significant effect on root biomass and soil pH. The positive plant growth response to AMF was substantially reduced by biochar amendment. The wood biochar had no adsorption for mineral N, and it had 0.96 % adsorption for mineral P in aqueous solution. The results suggested that the negative effect of wood biochar application on plant growth may due to the reduced plant uptake of P and N and the possibility of phytotoxic effects of wood biochar on potato growth. It was concluded that the wood biochar used in current study had negative impact on plant growth and P/N uptake and it is not recommendable to apply this wood biochar to mycorrhizal agro-system, to soil fertilized with high rate of P or to soil suffering water deficiency.

To study the effects of early drought priming at 5th‐leaf stage on grain yield and nitrogen‐use efficiency in wheat (Triticum aestivum L.) under post‐anthesis drought and heat stress, wheat plants were first exposed to moderate drought stress (drought priming; that is, the leaf water potential reached ca. −0.9 MPa) at the 5th‐leaf stage for 11 days, and leaf water relations and gas exchange rates, grain yield and yield components, and agronomic nitrogen‐use efficiency (ANUE) of the primed and non‐primed plants under post‐anthesis drought and heat stress were investigated. Compared with the non‐primed plants, the drought‐primed plants possessed higher leaf water potential and chlorophyll content, and consequently a higher photosynthetic rate during post‐anthesis drought and heat stress. Drought priming also resulted in higher grain yield and ANUE in wheat under post‐anthesis drought and heat stress. Drought priming at vegetative stage improves carbon assimilation and ANUE under post‐anthesis drought and heat stress and their combination in wheat, which might be used as a field management tool to enhance stress tolerance of wheat crops to multiple abiotic stresses in a future drier and warmer climate.

Plant growth and development are influenced by future elevated atmospheric CO 2 concentration and increased salinity stress. AM (arbuscular mycorrhiza) symbiosis has been shown to improve plant growth and resistance to environmental stresses. The aim of this study was to investigate the potential role of AM fungus in alleviating salinity stress in wheat (Triticum aestivum L.) plants grown under ambient and elevated CO 2 concentrations. Wheat plants inoculated or not inoculated with AM fungus were grown in two glasshouses with different CO 2 concentrations (400 and 700 lmol l À1 ) and salinity levels (0, 9.5 and 19.0 dS m À1 ). Results showed that salinity stress decreased and elevated CO 2 increased AM colonization. AM inoculation increased plant dry weight under elevated CO 2 and salinity stress. Stomatal conductance, density, size and aperture of AM plants were greater than non-AM plants. AM fungi enhanced NUE by altering plant C assimilation and N uptake. AM plants had higher soluble sugar concentration and [K + ]: [Na + ] ratio compared with non-AM plants. It is concluded that AM symbiosis improves wheat plant growth at vegetative stages through increasing stomatal conductance, enhancing NUE, accumulating soluble sugar, and improving ion homeostasis in wheat plants grown at elevated CO 2 and salinity stress.

Sun Y., Holm P.E., Liu F., 2014. Alternate partial root-zone drying irrigation improves fruit quality in tomatoes. Hort. Sci. (Prague),.Alternate partial root-zone drying (PRD) irrigation and deficit irrigation (DI) are water-saving irrigation strategies. Here, comparative effects of PRD and DI on fruit quality of tomato (Solanum lycopersicum L.) were investigated. The results showed that the irrigation treatments had no effect on tomato yield but significantly affected several organic and mineral quality attributes of the fruits. Compared to DI, PRD significantly increased the fruit concentrations of Ca and Mg, and fruit juice concentrations of total soluble solid, glucose, fructose, citric and malic acid, P, K and Mg. It is concluded that PRD is better than DI in terms of improving fruit quality, and could be a promising management strategy for simultaneous increase of water use efficiency and fruit quality in tomatoes.

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