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Effects of elevated CO 2 concentration ([CO 2 ]) and air temperature (T air ) on accumulation and intra-plant partitioning of dry matter (DM) and nitrogen in paddy rice were investigated by performing a pot experiment in six natural sunlit temperature gradient chambers (TGCs) with or without CO 2 fumigation. Rice (Oryza sativa L.) plants were grown in TGCs for a whole season under two levels of [CO 2 ] (ambient, 380 ppm; elevated, 622 ppm) and two daily T air regimes (ambient, 25.2°C; elevated, 27.3°C) in split-plot design with triplication. The effects of elevated [CO 2 ] and T air on DM were most dramatic for grain and shoot with a significant (P<0.05) interaction between [CO 2 ] and T air . Overall, total grain DM increased with elevated [CO 2 ] by 69.6% in ambient T air but decreased with elevated T air by 33.8% in ambient [CO 2 ] due to warming-induced floral sterility. Meanwhile, shoot DM significantly increased with elevated T air by 20.8% in ambient [CO 2 ] and by 46.6% in elevated [CO 2 ]. Although no [CO 2 ]×T air interaction was detected, the greatest total DM was achieved by co-elevation of [CO 2 ] and T air (by 42.8% relative to the ambient conditions) via enhanced shoot and root DM accumulation, but not grain. This was attributed largely both to increase in tiller number and to accumulation of photosynthate in the shoot and root due to inhibition of photosynthate allocation to grain caused by warming-induced floral sterility. Distribution of N (both soil N and fertilizer 15 N) among rice parts in responding to climatic variables entirely followed the pattern of DM. Our findings demonstrate that the projected warming is likely to induce a significant reduction in grain yield of rice by inhibiting DM (i.e., photosynthates) allocation to grain, though this may partially be mitigated by elevated [CO 2 ].

The effects of the liquid pig manure (LM) used in organic farming on the natural abundance of 15 N and 13 C signatures in plant tissues have not been studied. We hypothesized that application of LM will (1) increase d 15 N of plant tissues due to the high d 15 N of N in LM as compared with soil N or inorganic fertilizer N, and (2) increase d 13 C of plant tissues as a result of high salt concentration in LM that decreases stomatal conductance of plants. To test these hypotheses, variations in the d 15 N and d 13 C of Chinese cabbage (Brassica campestris L.) and chrysanthemum (Chrysanthemum morifolium Ramatuelle) with two different LMs (with d 15 N of +15.6 and +18.2%) applied at two rates (323 and 646 kg N ha -1 for cabbage and 150 and 300 kg N ha -1 for chrysanthemum), or urea (d 15 N = -2.7%) applied at the lower rate above for the respective species, in addition to the control (no N input) were investigated through a 60-day pot experiment. Application of LM significantly increased plant tissue d 15 N (range +9.4 to +14.9%) over the urea (+3.2 to +3.3%) or control (+6.8 to 7.7%) treatments regardless of plant species, strongly reflecting the d 15 N of the N source. Plant tissue d 13 C were not affected by the treatments for cabbage (range À30.8 to À30.2%) or chrysanthemum (À27.3 to À26.8%). However, cabbage dry matter production decreased while its d 13 C increased with increasing rate of LM application or increasing soil salinity (P < 0.05), suggesting that salinity stress caused by high rate of LM application likely decreased stomatal conductance and limited growth of cabbage. Our study expanded the use of the d 15 N technique in N source (organic vs. synthetic fertilizer) identification and suggested that plant tissue d 13 C maybe a sensitive indicator of plant response to salinity stress caused by high LM application rates.Keywords d 13 C Á d 15 N Á Liquid livestock manure Á Organic input Á Salinity Á Synthetic fertilizer Abbreviations LMLiquid manure SM Solid manure

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