Abnormally altered precipitation patterns induced by climate change have profound global effects on crop production. However, the plant functional responses to various precipitation regimes remain unclear. Here, greenhouse and field experiments were conducted to determine how maize plant functional traits respond to drought, flooding, and rewatering. Drought and flooding hampered photosynthetic capacity, particularly when severe and/or prolonged. Most photosynthetic traits recovered after rewatering, with few compensatory responses. Rewatering often elicited high photosynthetic resilience in plants exposed to severe drought at the end of plant development, with the response strongly depending on the drought severity/duration and plant growth stage. The associations of chlorophyll concentrations with photosynthetically functional activities were stronger during post-tasselling than pre-tasselling, implying an involvement of leaf age/senescence in responses to episodic drought and subsequent rewatering. Coordinated changes in chlorophyll content, gas exchange, fluorescence parameters (PSII quantum efficiency and photochemical/non-photochemical radiative energy dissipation) possibly contributed to the enhanced drought resistance and resilience and suggested a possible regulative trade-off. These findings provide fundamental insights into how plants regulate their functional traits to deal with sporadic alterations in precipitation. Breeding and management of plants with high resistance and resilience traits could help crop production under future climate change.

To provide scientific support for planning maize production and designing countermeasures against the effects of climate change on the national maize crop, we analyzed the climatic suitability for cultivating maize across China. These analyses were based on annual climate indices at the Chinese national level; these indices influence the geographical distribution of maize cultivation. The annual climate indices, together with geographical information on the current cultivation sites of maize, the maximum entropy (MaxEnt) model, and the ArcGIS spatial analysis technique were used to analyze and predict maize distribution. The results show that the MaxEnt model can be used to study the climatic suitability for maize cultivation. The eight key climatic factors affecting maize cultivation areas were the frost-free period, annual average temperature, ≥0°C accumulated temperature, ≥10°C accumulated temperature continuous days, ≥10°C accumulated temperature, annual precipitation, warmest month average temperature, and humidity index. We classified climatic zones in terms of their suitability for maize cultivation, based on the existence probability determined using the MaxEnt model. Furthermore, climatic thresholds for a potential maize cultivation zone were determined based on the relationship between the dominant climatic factors and the potential maize cultivation area. The results indicated that the importance and thresholds of main climate controls differ for different maize species and maturities, and their specific climatic suitability should be studied further to identify the best cultivation zones. The MaxEnt model is a useful tool to study climatic suitability for maize cultivation. maize, planting distribution, dominant climatic factor, climatic suitability, maximum entropy (MaxEnt) model Citation:He Q J, Zhou G S. The climatic suitability for maize cultivation in China.

To investigate the molecular response of brown planthopper, Nilaparvata lugens (BPH) to BPH-resistant rice plants, we isolated cDNA fragments of the genes encoding for carboxylesterase (CAR), trypsin (TRY), cytochrome P450 monooxygenase (P450), NADH-quinone oxidoreductase (NQO), acetylcholinesterase (ACE), and Glutathione S-transferase (GST). Expression profiles of the genes were monitored on fourth instar nymphs feeding on rice varieties with different resistance levels. Northern blot hybridization showed that, compared with BPH reared on susceptible rice TN1, expression of the genes for P450 and CAR was apparently up-regulated and TRY mRNA decreased in BPH feeding on a highly resistant rice line B5 and a moderately resistant rice variety MH63, respectively. Two transcripts of GST increased in BPH feeding on B5; but in BPH feeding on MH63, this gene was inducible and its expression reached a maximum level at 24 h, and then decreased slightly. The expression of NQO gene was enhanced in BPH on B5 plants but showed a constant expression in BPH on MH63 plants. No difference in ACE gene expression among BPH on different rice plants was detected by the RT-PCR method. The results suggest these genes may play important roles in the defense response of BPH to resistant rice.

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