Some Eco-Physiological Characteristics at R4-R5 Stage in Relation to Soybean Yield Differing in Maturities

Digital plant canopy imager and photosynthesis analyzer system were used to analyze thecharacteristics of canopy structure, photosynthetic physiology and micro-environmentalfactors at R4-R5 stage in different yielding soybean cultivars or lines with differentmaturities. The results showed that the common characteristics of high yielding soybeancultivars were high LAI, uniform foliage distribution in all horizontal directions, lessvariance of photosynthetic rate between top and bottom leaves in canopy and relativelyhigher photosynthetic rate of the whole canopy. All these characters combined in allresulted in higher canopy photosynthetic productivity, and pod number, seed number andseed weight per plant, especially pod and seed number in top and middle canopy wereincreased. The characters of high yielding canopy varied among maturities. Light interceptionwas more important to early cultivars. Less foliage inclination angle was benefit tointercept more solar energy during yield formation. As late soybean cultivars had a moreclosure canopy and higher LAI, greater foliage inclination angle in all layers of highyielding canopy made more solar radiation penetrate into canopy, which was beneficial toyield formation.

Fertilization Management for Improving Quality Properties of Spring Wheat in Northeast China

AbstractFertilization management to improve quality properties of spring wheat cultivars has received little research attention inNortheast China. In this study, the effects of different fertilization management regimes on the quality properties of springwheat cultivar New Kehan 9 (Triticum aestivum L.) were investigated for two years. The results showed that fertilizationconsistently increased wheat yield, and the highest yield was obtained with addition of N, P and NPK fertilizers. The NPKtreatment resulted in 50% more yield than the unfertilized plot. The average increases in protein content from NPK and NP atseeding + N at anthesis over no fertilization and NP fertilizers at seeding were 2.7% and 0.90% respectively. The highestprotein yields were achieved in NPK and NPK + N treatments, and the lowest protein yield was observed in the no fertilizertreatment due to both low protein content and grain yield. Fertilization increased gliadins content, but decreased gluteninscontent, thus the gliadins/glutenins ratios were higher in the fertilization treatments. The most obvious effect of fertilizationon kernel quality was the significant increase of hardness percentage. Although the dough rheological properties werenot strongly changed by fertilization, dry gluten and wet gluten were significantly increased, and the highest breadvolume and bread score were found in the NPK treatment in both years. The application of 3% urea at anthesis, or applying45 kg ha-1 of potassium sulphate at seeding, with urea and diammonium phosphate as basal applications, significantlyincreased protein yield and improved quality properties of this wheat cultivar.Key words: Fertilization, Yield, Protein contents, Protein fractions, Quality, Spring

Phytoextraction:A Cost-effective Approach to Metal-contaminated Soils

This paper will review the topic of phytoextraction,a major approach of phytoremediation,by clarifying the roles of hyperaccumulators,bio-mechanisms involved,issues regarding contaminant uptake,artificial chelation,genetic selection,and cultivation.The paper will also address the practical issues and the regulatory context of this emerging technology and briefly discuss avenues for future research.

Sodium-Zinc Exchange Selectivity on Wyoming Montmorillonite in Different Background Anion Solutions

The effect of background anion on cation exchange reactions,such as Na-Ca and Na-Cu exchange reactions,on montmorillonites has been studied,but the results are not always clear and discrepancies exist in the literature.In this study,the exchange of zine(Zn^2+)for sodium(Na^+)on Wyoming montmorillonite was investigated at 298°K using Cl^-,ClO4^-,NO3^-,OAc^-,and SO4^2- solution media at a constant total metal charge concentration of 0,0200 molc L^-1.Results indicated that the clay CEC values were essential similar for Cl^-,ClO4^-,NO3^- and SO4^2- solution media with an average CEC of 0.856±0.008 molc kg^-1;in an OAc^- solution the clay CEC was much higher than that in other anion media.The specific adsorption of Zn(SAZn),as defined by the extraction of Zn using 0.05 mol L^-1 Na2-EDTA,was different in the various background solutions.The highest value for SAZn was 0.359±0.0350 molc kg^-1,which occurred in OAc solution.There was essentially no difference in the total apparent adsorbed metals(the sum of adsorbed equivalents of Na and Zn per kilogram of clay,Q)among the various background solutions.The average Q for all anion media was 0.807±0.011 molc kg^-1 and was independent of exchanger composition.Experimental results indicated that there were no significant monovalent cation complexes such as ZnCl^+ or ZnNO3^+ that were adsorbed by montmorillonite.The Na-Zn exchange isotherms indicated that there was an adsorption preference for Zn over Na on Wyoming montmoorillonite.

Row Spacing in Relation to Competition for Limited Resources in Soybean (Glycine Max L. Merrill)

Growing soybeans in different row-spacings introduces competition. Competition begins when the immediate supply of a single necessary factor falls below the combined demands of all plants. This paper reviews the main competition factors of genotypes, light, water, nutrients and weed in responses to row spacings for the past four decades. It demonstrated that responses of soybean genotypes to row width differ among cultivars, which depend on seasonal rainfall and irrigation. Determinate types produce more yield in narrow-rows, and cultivars with lodging resistance should be adopted in narrow-spacings, but indeterminate soybean should also be used to optimize yields in certain system. Narrow-compared with wide-row soybean (Glycine max) cultivation increases light interception (LI) and dominant components for the increase come from LAI, light extinction coefficients and branch types. Water use efficiency (WUE) and evapotranspiration are not influenced by row spacing, but seed yield could be increased if irrigation is applied. Nutrient uptake is significantly affected by row spacing, seed yields and uptake of N, P, K in plants increases with decreasing row spacing, and the effects depend on the fertilizer levels. Other factors rather than row spacing affect nitrogen fixation. Weed density, peak time and periodicity of weed emergence are not affected by row spacing, but better complementary weed control by the herbicides at the used doses can be obtained in narrow spacing due to the reduced weed number and dry weight. More researches are required to investigate the physiological responses, nutrient and water uptake and translocation, light utilization at different layers of canopy and soil environment changes in different row-spacings.

Nylon Filter Arrays Reveal Differential Expression of Expressed Sequence Tags in Wheat Roots Under Aluminum Stress

To enrich differentially expressed sequence tags (ESTs) for aluminum (Al) tolerance, cDNA subtraction libraries were generated from Al-stressed roots of two wheat (Triticum aestivum L.) nearisogenic lines (NILs) contrasting in Al-tolerance gene(s) from the Al-tolerant cultivar Atlas 66, using suppression subtractive hybridization (SSH). Expression patterns of the ESTs were investigated with nylon filter arrays containing 614 cDNA clones from the subtraction library. Gene expression profiles from macroarray analysis indicated that 25 ESTs were upregulated in the tolerant NIL in response to Al stress. The result from Northern analysis of selected upregulated ESTs was similar to that from macroarray analysis. These highly expressed ESTs showed high homology with genes involved in signal transduction, oxidative stress alleviation, membrane structure, Mg2+ transportation, and other functions. Under Al stress, the Al-tolerant NIL may possess altered structure or function of the cell wall, plasma membrane, and mitochondrion. The wheat response to Al stress may involve complicated defense-related signaling and metabolic pathways.The present experiment did not detect any induced or activated genes involved in the synthesis of malate and other organic acids in wheat under Al-stress.