Effect of nitrogen root zone fertilization on rice yield,uptake and utilization of macronutrient in lower reaches of Yangtze River,China

Improper application of nitrogen (N) has led to high N losses and low N use efficiency in the lower reaches of Yangtze River in China. An effective method to solve such problems is the deep fertilized N in root zone (RZF). Limited information is available on the effect of RZF on the uptake of macronutrients (N, P and K) and rice yield. Field experiments, conducted from 2014 to 2015, compared the farmer fertilizer practice (FFP, with 225 kg ha^?1 of N, split into three doses) and RZF using the same rate but placing N 5 cm away from rice roots in holes 10 cm deep (RZF10) or 5 cm deep (RZF5) as a single application. The highest mean yield (10.0 t ha^?1) was obtained in RZF10, which was 19.5% more than that in FFP. Root zone fertilization of urea (whether 10 cm deep or 5 cm deep) resulted in greater accumulation of N, P and K in stem, leaf sheaths, leaf blades and grains compared to that in FFP in sandy and in loam soils. The uptake of N, P and K was the highest in RZF10 (average at 176.7, 66.2 and 179.1 kg ha^?1, respectively), higher than that in FFP by 45.0, 17.0 and 22.6%, respectively. N apparent recovery efficiency was markedly higher in RZF10 (53.1%) than in FFP (27.5%). RZF10 significantly increased the N, P, K uptake compared with FFP under different N rates in both sandy and loam soils. These results suggest that the N, P and K input amount should be re-determined under RZF.     

A simultaneous estimation procedure for the parameters of the maximum size–density line and self-thinning curve to predict stand development of fast-growing tropical species

A simultaneous estimation procedure for the parameters of two functions, i.e., the maximum size–density line and the self-thinning curve, is presented to predict stand development for fast-growing tropical species. This procedure assumes that the rate of periodic reduction in stand density with increasing quadratic mean diameter on a logarithmic scale (r) will increase inversely proportionally to the distance from the maximum size–density line and consequently equals the slope of the line at distance 0. Under this assumption, the maximum size–density line can be incorporated into the self-thinning curve to form an integrated equation with three parameters: k and m, the slope and constant of the maximum size–density line, and a, the rate of reduction of r of the self-thinning curve. These parameters are estimated simultaneously using measurement data on stand density, quadratic mean diameter, and the corresponding r. This procedure was evaluated by application to two data sets: 186 measurements of Acacia mangium and 95 measurements of Paraserianthes falcataria, for which the parameters k and m have previously been calculated. The parameters estimated using this procedure were in good agreement with previous ones based on the A. mangium data set, and the differences found for the P. falcataria data set were also small, within the error variances. Therefore, it is concluded that the proposed procedure would give almost the same estimates from a single calculation step as the previous procedure that required two separate calculation steps.     

Seasonal Variability in Stormwater Quality Treatment of Permeable Pavements Situated Over Heavy Clay and in a Cold Climate

Permeable pavements mitigate the impacts of urbanization on surface waters through pollutant load reduction, both by sequestration of pollutants and stormwater volume reduction through exfiltration. This study examined the non-winter water quality performance of two side-by-side permeable pavements in the Ohio snowbelt. The permeable interlocking concrete pavements were designed to drain impervious catchments 2.2 (large) and 7.2 (small) times larger than their surface area, were located over clay soils, and incorporated the internal water storage design feature. Nutrient reduction was similar to past studies—organic nitrogen and particulate phosphorus were removed through filtration and settling, while dissolved constituents received little treatment. Because of 16 and 32 % volume reductions in the small and large installations, respectively, nutrient loads were often significantly reduced but generally by less than 50 %. Aluminum, calcium, iron, magnesium, lead, chloride, and total suspended solids (TSS) concentrations and loads often increased after passing through the permeable pavements; effluent TSS loads were three- to five-fold higher than influent TSS loads. This was apparently due to seasonal release of clay- and silt-sized particles from the soils underlying the permeable pavement and inversely related to elapsed time since winter. The application of de-icing salt is thought to have caused deflocculation of the underlying soils, allowing particulates to exit with stormwater as it discharged from the underdrain of the permeable pavements. By autumn, both permeable pavements discharged metals and TSS concentrations similar to others in the literature, suggesting the de-icing effects lasted 3–6 months post-winter. Sodium may substantially affect the performance of permeable pavements following winter de-icing salt application, particularly when 2:1 clay minerals, such as vermiculites and smectites, predominate.     

Contamination and browning in tissue culture of Platanus occidentalis L.

Twigs of 2–3-year-old Platanus occidentalis L. were used as experimental material to find the causes for the contamination and browning in the initial stages of tissue cultures. To compare the degree of browning of explants picked off from different growing seasons, the experimental material was excised from trees on each of the first ten days in January, March, May and July, 2006. The results indicated that the contamination and browning rates of the material cut off in January (14.2% and 30.6%, respectively) and March were somewhat lower than those in July. The pretreatment of soaking the explants in different anti-oxidants and absorbents at the same time could diminish some side effects. The pretreatment of using 10 g·L–1 vitamin C reduced the contamination and brown-ing rate effectively. An orthogonal experiment showed that the optimal factor and level arrangement is 0.5 mg·L–1 BA, 2.0 g·L–1 ac-tive carbon and 1.5 g·L–1 PVP which resulted in a browning rate of only 16.5%. In general, sampling period, physical properties and pretreatment of explants are the main factors responsible for the contamination and browning of material in the initial stages of P. occidentalis tissue cultures.     

Development of a label-free immunosensor system for detecting oocyte maturation-inducing hormone in fish

A label-free immunosensor for detecting the oocyte maturation-inducing hormone 17, 20β-dihydroxy-4-pregnen-3-one (DHP), was developed. A principle of the sensor system was based on differences in electrochemical activity changed by an immunoreaction in the absence and presence of DHP. For preparation of the immunosensor, anti-DHP IgG was immobilized on an Au working electrode modified with a self-assembled monolayer of 3-mercaptopropionic acid. The sensor was immersed into a sample solution containing DHP. DHP was determined by cyclic voltammetry. The immunosensor showed a specific response to DHP, and the oxidation peak current linearly decreased in the range of 7.8–500 pg ml⁻¹ with a correlation coefficient of 0.996. The sensor system was applied to determine the DHP levels in plasma of goldfish and was compared with the DHP levels of the same samples determined using an ELISA as the conventional method. Good correlation was obtained between values determined using both methods in the range of 0.1–7.7 ng ml⁻¹ (correlation coefficient 0.876). These findings suggest that the proposed label-free immunosensor can be used to analyze DHP levels in fish plasma samples.     

Molecular diversity of Egyptian cotton (<Emphasis Type="Italic">Gossypium barbadense</Emphasis> L.) and its relation to varietal development

Twenty-eight Egyptian cotton (Gossypium barbadense L.) genotypes (varieties and hybrids) were used for analysis of genetic diversity using DNA based markers (ISSR, SSR, and EST) and to study varietal development of cotton. The ISSR markers gave the highest percentage of polymorphic bands as well as polymorphic information content compared with the other molecular markers (i.e. EST and SSR markers). Using clustering analysis, no general clustering according to the pedigree history of the genotypes was observed. Using principal coordinate analysis (PCOORDA), cotton genotypes were separated by the first three principal coordinates (PC1, PC2, and PC3) accounting for 11.5, 8.6, and 7.2% of the total genetic variance, respectively. The cotton genotypes were distributed into three parts based on the first PC, each part containing a group of varieties having a common ancestor. ‘Giza 12’ variety was the common ancestor for the varieties included in the first part and ‘Ashmouni’ variety was the common ancestor for the varieties included in the second part, while both ‘Sakha 3’ and ‘Sakha 4’ varieties were common ancestors for the varieties included in the third part. The results of the PCOORDA also showed better resolution of the genetic diversity than cluster analysis especially in the illustration of the varietal development of cotton. That means that principal coordinate analysis can be strongly used either alone or in combination with cluster analysis to discuss both genetic diversity and varietal development in the cotton genotypes.     

First report of leaf spot caused by <Emphasis Type="Italic">Alternaria alternata</Emphasis> on <Emphasis Type="Italic">Drimia maritima</Emphasis>

Drimia maritima (squill) is a historically important medicinal plant. During the spring of 2016, small, yellow leaf spots, which became brown and finally necrotic, were observed on squill plants in Kohgiluyeh and Boyer-Ahmad Provinces in Iran. A fungus was consistently isolated from infected leaves and identified as Alternaria alternata based on morphological and phylogenetic analyses. Pathogenicity tests confirmed A. alternata to be the causal agent of the newly observed leaf spot disease. This is the first report of leaf spot on D. maritima caused by A. alternata in the world.     

A systematic and quantitative approach to improve water use efficiency in agriculture

As the competition for the finite water resources on earth increases due to growth in population and affluence, agriculture is faced with intensifying pressure to improve the efficiency of water used for food production. The causes for the relatively low water use efficiency in agriculture are numerous and complex, including environmental, biological, engineering, management, social, and economic facets. The complexity of the problem, with its myriads of local variations, requires a comprehensive conceptual framework of the underlying physical and biological processes as the basis to analyze the existing situation and quantify the efficiencies, and to plan and execute improvements. This paper proposes such a framework, based on the simple fact that the overall efficiency of any process consisting of a chain of sequential step is the product of the efficiency (i.e., output/input ratio) of its individual component steps. In most cases of water use, a number of process chains, both branching and merging, are involved. Means to integrate the diverging and converging chains are developed and presented as equations. Upscaling from fields to regions and beyond are discussed. This chain of efficiencies approach is general and can be applied to any process composed of chains of sequential steps. Here the framework is used to analyze the systems of irrigated and dryland crop production, and animal production on rangeland. Range of plausible efficiencies of each step is presented as tables, with values separately for the poor and for the good situation of circumstances, management and technology. Causes of the differences in efficiency of each step, going from water delivery to soil water extraction, transpiration, photosynthesis, and conversion to crop biomass and yield, and to animal product are briefly discussed. Sample calculations are made to demonstrate how modest differences in the efficiencies of the component steps are manifested as large to huge differences in the overall efficiency. Based on an equation quantifying the impact of changes in efficiency of component steps on the overall efficiency, it is concluded that generally, it is more effective to made modest improvements in several or more steps than to concentrate efforts to improve one or two steps. Hence, improvement efforts should be systematic and not overly concentrated on one or two components. The potential use of the same equation as the point of departure to optimize the allocation of economic resource among the component steps to maximize the improvement in the overall water use efficiency is elaborated on. The chain of efficiencies framework provides the means to examine the current levels of efficiency along the pathways of agricultural water use, to analyze where inefficiencies lie by comparing with the range of known efficiency values in the tables presented, to assess the potential improvements that may be achieved in various parts and their impact on the overall efficiency, and to aid in the optimal allocation of resources for improvements.

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