Abstract:Maize (Zea mays L.) is ranking first in total yield production of the crop species in China, whereas this important crop is sensitive to salt stress. As the salinization of farmlands has become one of the major environmental stresses that decrease maize yield and quality, it is important to study the mechanism of salt tolerance and thus facilitate the development of salt-tolerant maize. It’s known that high-salt concentration can damage maize plant mainly by causing osmotic stress and ion toxicity. In recent years, several salt-tolerant QTL or genes which are involved in regulating either ion homeostasis or osmotic tolerance, have been identified by GWAS and/or QTL analysis, and their functional mechanisms have been investigated. Here, we review recent progress on deciphering the mechanisms of salt tolerance in maize.

Abstract:A kind of auxiliary identification method of sweetpotato drought-resistance need be established to drought screening of new materials and breeding drought-resistance new varieties，promote sweetpotato planting in dry barren hills，inland arid etc. marginal land，reduce the workload of field identification. On the basis of identification of sweetpotato drought-resistance in the field, PEG-6000 simulate water stress, the relation of drought-resistance and physiological changes under was discussed. The results show that: Through drought identification in the field, Guangshu87 and Xushu22 have strong drought-resistance, Rizi0602 and Ningzishu1 have poor drought-resistance. Under stress, with the increasing of PEG concentration , the activity of NOS, CAT, T-AOC and T-SOD of sweetpotato leaves increased gradually, the content of Pro, MDA, Prot and T-AA also increased; especially after 24 h sweetpotato leaves were treated in 25% PEG-6000, drought resistance index and the relative values of NOS,T-AOC,Pro of sweetpotato leaves showed a significant positive correlation，the relative value of RWC and drought resistance index showed a highly significant positive correlation，drought resistance index and D value of NOS,T-AOC, Pro, RWC showed a significant positive correlation（r=0.8944）.so the D value of this four physiological indexes could be used for preliminary identification of sweetpotato drought-resistance.

Abstract:Polyethylene glycol (PEG)-6000, mannitol and sucrose were employed as osmotica for simulating water stress to identify drought resistance at germination stage of wheat. Three osmotica with osmotic potential from -0.25MPa to 1.50MPa were compared. Germinal bud growth in sucrose was inhibited because of molding and stress. Germinal bud elongation was inhibited in -0.25MPa PEG-6000 and -0.50MPa mannitol. Germination percentage significantly decreased in -0.50MPa PEG-6000 and -1.00MPa mannitol. Both of germination percentage and germinal bud length decreased with the increase of osmotic stress because the speed of water absorbing by grains was slow in osmotic stress solutions, and further resulted in lower grain relative water content (RWC) and lower osmotic potential than in water. All parameters associated with germination decreased more seriously in PEG-6000 than in mannitol at the same osmotic potential. For the purpose of evaluating drought resistance of wheat genotypes by identifying germination percentage in osmotic stress solution, -0.50MPa PEG-6000 or -1.00MPa mannitol is ideal, but -0.50MPa PEG-6000 should be preferred if the experiment cost is considered.