Bao Shan Wang

Increase in unsaturated fatty acids in membrane lipids of Suaeda salsa L. enhances protection of photosystem II under high salinity

In order to examine the possible role of unsaturated fatty acids in photosynthesis of halophytes under high salinity, the effect of salinity on plant growth, chlorophyll (Chl) content, photochemical efficiency of PSII, membrane lipid content and fatty acids composition of a C3 euhalophyte Suaeda salsa L. was investigated. Salt stress induced a slight increase of the maximal photochemical efficiency of PSII (Fv/Fm), actual PSII efficiency (ΦPSII), Chl a content and Chl a/b ratio. The unsaturated fatty acid content also increased under salt stress. The proportion of MGDG, DGDG, SQDG, and PC decreased, while the proportion of PG increased from 10.9% to 26.9% under salt stress. These results suggest that S. salsa displays high resistance to photoinhibition under salt stress and that increased concentration of unsaturated fatty acids in membrane lipids of S. salsa enhances the tolerance of photosystem II to salt stress.

Relationships between ion and chlorophyll accumulation in seeds and adaptation to saline environments in Suaeda salsa populations

Abstract The importance of ion and chlorophyll accumulation was evaluated in brown seeds of a Suaeda salsa population from an intertidal zone and one from a saline inland zone during seed development. The results showed that more NO3 − and K+, but less Cl− and Na+ in leaves and stems were translocated to the embryos in the intertidal population than the inland population; more Cl− and Na+ were compartmentalized in the pericarps of the intertidal population compared to the inland population, which indicates that the two populations have different ability to accumulate ions in different plant parts. The embryos of fresh premature seeds contained chlorophyll and the embryos could release oxygen. The content of chlorophyll markedly decreased, and there was no oxygen production in the embryos of dry mature seeds in both populations. These characteristics may affect the distributions of the two S. salsa populations in their natural saline environments.

Effects of NaCl stress on the growth and photosynthetic characteristics of Ulmus pumila L. seedlings in sand culture

The effects of NaCl stress on the growth and photosynthetic characters of Ulmus pumila L. seedlings were investigated under sand culture condition. With increasing NaCl concentration, main stem height, branch number, leaf number, and leaf area declined, while Na+ content and the Na+/K+ ratio in both expanded and expanding leaves increased. Na+ content was significantly higher in expanded leaves than in those just expanding. Chlorophyll (Chl) a and Chl b contents declined as NaCl concentration increased. The net photosynthetic rate, intercellular CO2 concentration, stomatal conductance, and transpiration rate also declined, but stomatal limitation value increased as NaCl concentration increased. Both the maximal quantum yield of PSII photochemistry and the effective quantum yield of PSII photochemistry declined as NaCl concentration rose. These results suggest that the accumulation of Na+ in already expanded leaves might reduce damage to the expanding leaves and help U. pumila endure high salinity. The reduced photosynthesis in response to salt stress was mainly caused by stomatal limitation.

The role of cotyledons in the establishment of Suaeda physophora seedlings

The role of cotyledons in seedling establishment of the euhalophyte Suaeda physophora under non-saline and saline conditions (addition of 1 mM or 400 mM NaCl) was investigated. Survival and fresh and dry weights were greater for seedlings grown in the light (12-h light/12-h dark) than in the dark (24-h dark). The shading of cotyledons tended to decrease shoot height, shoot organic dry weight, number of leaves, and survival of seedlings regardless of NaCl treatment, but the effect of cotyledon shading was greater with 400 mM NaCl. Concentrations of Na+ were higher in cotyledons than in leaves, regardless of NaCl treatment. The K+/Na+ ratio was lower in cotyledons than in leaves for seedlings treated with 1 mM NaCl but not for seedlings treated with 400 mM NaCl. Addition of 400 mM NaCl decreased oxygen production in cotyledons but especially in leaves. These results are consistent with the hypothesis that, by generating oxygen via photosynthesis and by compartmentalizing Na+, cotyledons are crucial for the establishment of S. physophora seedlings in saline environments.

Planting Sweet Sorghum in Yellow River Delta: The Cultivation Measure, Yield and Effect on Soil Microflora

Field experiment was conducted in the saline soil of Yellow River Delta between May to Oct. Sweet sorghum was planted with different cultivation measures to test the effect of plastic mulch, plant density, organic manure application and additional fertilizer application on the yield, stalk juice Brix and extraction rate. The soil bacteria and actinomycetes quantities were also determined after harvesting to test the amelioration effects of different measures on soil.

The Cultivation Technique for Increasing the Stalk Sugar Content of Energy Plant Sweet Sorghum in Yellow River Delta

This study was carried out to investigate the suitable technique for increasing the stalk sugar content of two sweet sorghum cultivars (salt-tolerant cultivar Jitianza 2 and salt-sensitive cultivar Lvneng 1) in saline soils of Yellow River Delta. Stalk sugar content of sweet sorghum in saline soil was significantly increased using the following integrated cultivation technique: (1) increasing organic fertilizer level; (2) applying optimum phosphorus and potassium fertilizer; (3) surface fertilizer application; (4) cultivating salt-tolerant sweet sorghum cultivars; (5) planting with plastic mulching; (6) planting in the early of the optimum seedling time (sowing as early as possible); (7) removing tillers during seedling stage; (8) cutting spike by half-strength before flowering. Jitianza 2 had higher stalk Brix than Lvneng 1 under the same cultivation condition. Therefore, planting salt-tolerant sweet sorghum cultivars in saline soil combined with these integrated cultivation techniques can get higher stalk sugar content in Yellow River Delta of China, which was beneficial for energy alcohol production from sweet sorghum.

The Bioenergy Plant Hybrid Pennisetum Improves Chilling Resistance by Enhancing the Unsaturation of Membrane Lipid under Low Temperature

Hybrid Pennisetum (Pennisetum americanum × P. purpureum) is a widely used bioenergy grass that could also serve as forage for livestock production. In a pot experiment, breed No.1 and breed No. 2 of hybrid Pennisetum were treated with 15°C /10°C day/night temperature for 10 days. Results showed that yield and photosynthesis of breed No. 1 were higher than those of breed No. 2 under low temperature. The unsaturated fatty acid content and the DBI (double bond index) of the major membrane lipid of MGDG (monogalactosyldiacylglycerols), DGDG (digalactosyldiacylglycerols), PG (phosphatidylglycerols), PC (phosphatidylcholines) and PE (phosphatidylethanolamine) of breed No. 1 were significantly increased, while significantly decreased for breed No. 2. We also observed an increase in the proportion of unsaturated fatty acids and a decrease in the proportion of saturated fatty acids under low temperature for breed No. 1, while it was reverse for breed No. 2. Thes results inducate that chilling resistance of breed No. 1 was improved by enhancing the unsaturation of membrane lipid under low temperature. These findings would be useful for understanding mechanism of chilling resistance and the production of hybrid Pennisetum as a biofuel on saline land in the Northern of the China.

Selective Transport Capacity for K+ and Ca2+ over Na+ of Leaf Sheath is Correlated with Salt Tolerance of Energy Plant Sweet Sorghum

Two sweet sorghum varieties (salt tolerant Jitianza 2 and salt sensitive Lvneng 1) were used to investigate their adaptation to NaCl stress under different cultivation conditions of potted cultivation and field cultivation, and selective transport capacity for K+ over Na+, and Ca2+ over Na+ of leaf sheath. NaCl stress decreased Pn, Fv/Fm, fresh weight of leaf sheath and leaf blade, field yield in both varieties. NaCl stress induced Na+ accumulation while it decreased K+ and Ca2+ levels in leaf sheath and leaf blade of both varieties. The increase in Na+ of leaf blade and the decrease in K+ and Ca2+ of leaf blade were greater in Lvneng 1 than those in Jitianza 2. Furthermore, the Na+, K+ contents in leaf sheath of Jitianza 2 were significantly higher than those of Lvneng 1 under NaCl stress. The selective transport capacity for K+ over Na+, and Ca2+ over Na+ of leaf sheath in Jitianza 2 was significantly greater than that in Lvneng 1. Pn, Fv/Fm, stem stalk field, ear field, juice yield, stalk Brix, sugar content of Jitianza 2 were significantly higher than those of Lvneng 1, which was correlated with stronger selective transport capacity for K+ over Na+, Ca2+ over Na+ of Leaf Sheath of Jitianza 2.

Planting Sweet Sorghum in Yellow River Delta: Agronomy Characters of Different Varieties and the Effects of Sowing Time on the Yield and other Biological Traits

In order to screen out the optimum varieties of sweet sorghum to be planted in Yellow River Delta, the agronomy characters of different varieties (strains) of sweet sorghum including jitianza 1 (JZ1), jitianza 2 (JZ2), jitianza 3 (JZ3), jitianza 4 (JZ4), liaosiza 1 (LSZ1), liaotian 1 (LT1), liaotian 3 (LT3), liaotian 6 (LT6) planted in the saline soil of Yellow River Delta were analyzed; Further more, the effect of different sowing time on the agronomy characters of sweet sorghum was explored with JZ2. The study provided bases for the cultivation of sweet sorghum in saline-alkali soil of Yellow River Delta in order to transform the biomass into bio-energy such as fuel alcohol.

Elevated N Supply Reduces the Inhibition of Growth and Photosynthesis Caused by Salinity in the Bioenergy Plant Hybrid Pennisetum

Hybrid Pennisetum (Pennisetum americanum × P. purpureum) is a popular bioenergy grass that could also serve as forage for livestock production. In a pot experiment, salinity inhibited hybrid Pennisetum growth, photosynthesis, soluble sugar content, and NR activity; decreased K+ content; and increased Na+ content. These adverse effects of soil salinity were reduced, however, by applications of NO3--N up to 5 mmol·L-1; higher applications of NO3--N increased soil salinity problems. These findings will be useful for the production of hybrid Pennisetum as a biofuel on saline land.