Irrigation,a productive tool for food security – a review

Water scarcity in agriculture is becoming a major problem due to increasing demand from nonagricultural uses and intensive crop management on existing croplands to meet the needs of an expanding global population. Efficient use of the available irrigation water is therefore of important concern. Even though intensive research in the areas of crop physiology, irrigation engineering, agronomy and agricultural economics has developed several ways to improve the efficiency of irrigation water, a multidisciplinary approach is often regarded as the best future path to achieve further enhancements in meeting the forthcoming challenge of producing more and safety foods. Failure of irrigation production has profound effects on the welfare of all those employed in it and also their customers. Indeed, the scale of the industry is such that world food prices will be influenced by the overall performance of the irrigation farmers, but low food prices are essential to the welfare of the poorest people. The contribution of irrigation and water management to increased food production must come through both expansion of irrigation and improved management of existing water supplies. This review presents the past, current and future panorama of irrigation as a viable tool in ensuring food security on the globe. Considering past trends, this review empathizes that future irrigation technologies should be focused on providing the leadership and capacity to capture, develop and promote new irrigation practices and management systems to optimize production.     

Organic Carbon Dynamics along a Toposequence in a Peri‐urban Site

Abstract

The pattern of carbon (C) storage in soils has implications for agriculture and the environment. Dynamics of organic C, in the 0‐ to 20‐cm soil depth along a toposequence in a peri urban site in Sierra Leone, West Africa, were studied. Organic C was determined by the dry‐combustion method on the following aggregate size fractions: whole soil (<2000 µm), 250–2000 µm, 53–250 µm, and <53 µm.

Mean organic C content of whole soil ranged from 4.8% on the backslope to 9.3% on the toeslope. Organic C content of aggregate size fractions increased with decreasing aggregate size. The amount of soil and organic C present in aggregate size fractions, at all positions on the toposequence, decreased with decreasing aggregate size. In general, convex upper slopes had lower contents and amounts of organic C compared to lower concave areas. This study provided benchmark levels and patterns against which changes resulting from imminent urbanization can be measured.     

How well does a botanical garden collection of a rare palm capture the genetic variation in a wild population?

Conservation is increasingly central to the botanic garden mission. Living plant collections are important components of conservation. Critical evaluation of living conservation collections with population genetic analysis can directly inform ex situ conservation strategy. Here, we quantify the degree of genetic variation captured through a population-based collection protocol, and explore optimal sampling for ex situ conservation. An extensive living collection derived from one population of Leucothrinax morrisii (Arecaceae) provided a model system. We compared 58 specimens from the ex situ collection with 100 individuals from throughout the parent population via 6 ISSR loci. Random bootstrapped resamples of the data were made to model differently structured ex situ collections. Mean diversity (He) differed little between the collection (0.204) and the population (0.216), and genetic distance (D) was very close (0.036). Very few private alleles were found between the collection and the population. Allelic capture, as measured by percent of private alleles, was greater than 94%. Resampled collections of different sizes captured from 48% to 94% of alleles. Pairwise comparison of bootstrapped resamples suggests that increasing the representation of half-sibling groups does not significantly increase allele capture. Increase in allele capture with increasing sample size is greatest at low resample sizes, and showed diminishing returns as resample size increased. No appreciable increase in allele capture was gained through maintaining different half-sibling groups. These data inform sampling for ex situ conservation purposes, and recommend sample sizes of at least 15 individuals, with the upper limit based on resources.     

Natural product chemistry meets genetics: when is a genotype a chemotype?

The chemotype of a microbial or plant species has traditionally been defined as its profile of natural products, and the genotype has been defined as its genetic constitution or DNA sequence. The purpose of this perspective is to discuss applications of DNA genotyping, particularly by polymerase chain reaction (PCR)-amplification methods, to predicting natural product chemotypes of fungi and plants of importance in food and agriculture. Development of PCR genotyping for predicting chemotypes will require collaboration between molecular biologists and natural product chemists, as well as community standards for reporting data. PCR genotyping should be validated by chemical analysis of individuals that represent the allelic diversity of the target gene in the population. To avoid misinterpretation, it is critical to differentiate data obtained by genotyping from data obtained by chemical analysis. The obvious and appropriate solution is to retain the established meanings of genotype and chemotype, both of which have been in use for half a century in the fields of genetics and natural product chemistry.     

“double bunch” in a plantain germplasm in Nigeria: a new Genotype

In the course of germplasm exploratory work, a strain of a False Horn plantain cultivar was found which produced two bunches at fruiting. Cropping of the suckers of this material through three cycles showed that all the plants studied, produced two bunches of fruits. The results suggest that this plantain tentatively designated as double bunch, is of genetic origin arising probably from a mutation of the existing plantain cultivar. The implications for the identification of genetic diversity as well as for the evaluation and conservation of genetic resources are discussed.     

Breakfast eating and overweight in a pre-school population: is there a link?

OBJECTIVES: To analyse the socio-economic factors related to breakfast eating, the association between breakfast eating and overweight, and to gain a more thorough understanding of the relationship between these two elements in a population-based cohort of 4.5-year-old children. We hypothesised that a relationship could be observed between breakfast skipping and overweight independently of socio-economic factors such as ethnicity, maternal education, single parenting and family income. DESIGN: A population-based study whereby standardised nutritional interviews were conducted with each child's parent. The children's height and weight were taken by a trained nutritionist and parents were asked about their child's breakfast eating. SETTING: The analyses were performed using data from the Québec Longitudinal Study of Child Development (1998-2002), conducted by Santé Québec (Canada). SUBJECTS: Subjects were 1549 children between the ages of 44 and 56 months, with a mean age of 49 months. RESULTS: Almost a tenth (9.8%) of the children did not eat breakfast every day. A greater proportion of children with immigrant mothers (19.4% vs. 8.3% from non-immigrant mothers), with mothers with no high school diploma (17.5% vs. <10% for higher educated mothers) and from low-income families (15% for income of $39,999 or less vs. 5-10% for better income) did not eat breakfast every day. Not eating breakfast every day nearly doubled the odds (odds ratio=1.9, 95% confidence interval 1.2-3.2) of being overweight at 4.5 years when mother's immigrant status, household income and number of overweight/obese parents were part of the analysis. CONCLUSION: Although our results require replication before public policy changes can be advocated, encouraging breakfast consumption among pre-school children is probably warranted and targeting families of low socio-economic status could potentially help in the prevention of childhood obesity.     

Vertical stratification and trophic interactions among organisms of a soil decomposer food web – a field experiment using 15N as a tool

In this field study, we explored the spatial segregation between the litter- and humus-inhabiting organisms of the detrital food web using ¹⁵N-isotope technique. The study was established in 11 × 11 m plots fertilized with ¹⁵N-labelled urea. Ten years after urea application, soil samples were taken, both from the litter layer and the combined F+H layer. The samples were analysed for N content and the proportion of ¹⁵N in (i) the residual organic matter in the litter and F+H layer (excluding microbes), (ii) microbial biomass, and (iii) various feeding guilds of soil fauna. The basal resource, soil microbes, and the fauna were more enriched with ¹⁵N in the F+H layer than in the litter layer. In the litter layer, the ¹⁵N enrichment of the expected food source equalled the one of the consumers, whereas in the F+H layer all trophic groups, except microbes and small microbi-detritivores, showed a significantly lower ¹⁵N enrichment than their expected food source. The results indicate that large and mobile humus-inhabiting decomposers exploit the overlying litter layer as a feeding site, whereas the feeding of the more sedentary smaller organisms is restricted to the humus layer.     

波密县近30 a气候变化特征

根据西藏自治区林芝地区波密县气象局1981年1月-2010年12月的气温及降水资料,分析了波密县近30 a来的气候变化特征,得出近30 a来波密县降水量呈下降趋势,夏、秋季降水量减少较为明显,冬季降水量却呈上升趋势;年平均气温呈上升趋势,四季气温也呈上升趋势,尤其是冬季变暖最为明显;年极端最低气温的上升趋势远远大于极端高温的上升趋势。     

德州市近50 a来旱涝特征分析

对德州市1951-1999年的逐年降水数据、区域旱涝灾害成灾面积及降水与成灾之间的相关性进行统计分析.依据Z指标划分7个旱涝等级,给出旱涝指标与旱涝成灾面积的多年变化趋势以及它们之间的相关系数.结果表明:德州市近50 a来,降水变化呈下降趋势;1975年以前偏涝,间或有旱的年份出现,极涝年份为1953年、1961年、1964年;1975年以后偏旱,间或有涝的年份出现,极旱年份为1981年;旱灾面积越来越大,涝灾面积越来越少,20世纪60-70年代为旱涝灾害成灾面积变化的转折点.降水指标为该市今后旱涝预测提供了可能的途径.     

Testing a key assumption of wildlife buffer zones: is flight initiation distance a species-specific trait?

The distance at which animals flee an approaching predator is known as the ‘flight initiation distance’ (FID). Wildlife managers use FID to develop buffer zones to reduce human impacts on wildlife. Many variables have been demonstrated to influence FID leading one to question whether it can be viewed as a species-specific trait. We tested this critical assumption for developing buffer zones by experimentally approaching eight species of shorebirds found at six sites around Botany Bay, 15 km south of Sydney, Australia. Botany Bay encompasses a range of human impacted areas, from urban developments with high levels of human presence, through to National Parks and wildlife protection areas where human presence is significantly lower. We found that both species and site influenced the distance birds flew away from an approaching human. Importantly, however, there was no significant statistical interaction between site and species demonstrating that ‘flighty’ species were consistently flighty while more tolerant species were consistently tolerant. Taken together, these results suggest that FID can therefore be viewed as a species-specific trait for these shorebirds. The great variability in FID suggests that wildlife managers should be somewhat conservative in developing buffer zones, but they can use previously published FID data for a given species as guidelines for setting buffer zones.     

Nitrate removal from ground water — use of a nitrate selective resin and a low concentrated regenerant

A new, strong base, macro-porous anion exchange resin, Amberlite IRA 996, appeared to be more nitrate selective than sulfate selective in treating high nitrate concentrations (18 mg NO _inf3 ^sup? -N L^?1) in potable water. When regeneration is carried out in a closed circuit in which a biological denitrification reactor is incorporated to remove nitrate from the regenerant, regeneration salt requirement and brine production can be minimized. In this combination of ion exchange and biological denitrification, regeneration with 30 g NaHCO₃ L^?1) is possible in 6 hr at a flow rate of 11 BV hr^?1. Accumulation of sulfate in the closed regeneration circuit does not affect the nitrate capacity of the resin.     

Enzymatic synthesis of galacto-oligosaccharides in an organic-aqueous biphasic system by a novel β-galactosidase from a metagenomic library

Prebiotic galacto-oligosaccharides (GOS) were effectively synthesized from lactose in organic-aqueous biphasic media by a novel metagenome-derived β-galactosidase BgaP412. A maximum GOS yield of 46.6% (w/w) was achieved with 75.4% lactose conversion rate in the cyclohexane/buffer system [95:5 (v/v) cyclohexane/buffer] under the optimum reaction conditions (initial lactose concentration = 30% (w/v), T = 50 °C, pH 7.0, and t = 8 h). The corresponding productivity of GOS was approximately 17.5 g L(-1) h(-1). The GOS mixture consisted of tri-, tetra-, and pentasaccharides. Trisaccharides were the chief component of reaction products. These experimental results showed that a low water content, a high initial lactose concentration, and an elevated reaction temperature could significantly promote the transgalactosylation activity of β-galactosidase BgaP412; at the same time, the enhanced GOS yield in an organic-aqueous biphasic system is because of the fact that thermodynamic equilibrium can be shifted to the synthetic direction by reversing the normal hydrolysis.     

In situ labeling of legume residues with a foliar application of a 15N‐enriched urea solution

Abstract

Conventional methods for labeling of legume residues with ¹⁵N for the measurement of the transfer of nitrogen (N) to a succeeding crop are inadequate for zero‐tillage management where the residue is chemically desiccated. The study tests the feasibility of in situ labeling of legumes with ¹⁵N for the study of N transfer to a succeeding crop. A single foliar application of ¹⁵N‐labeled urea was misted onto the stems and leaves of second cut red clover and alfalfa in the field in 0.75 x 0.75 m microplots. Nitrogen content and ¹⁵N enrichment were determined for above‐ and below‐ground plant parts. Overall, recovery of the foliar applied ¹⁵N in the forage was 30% and 57% for the alfalfa and red clover, respectively. Of the nitrogen recovered, approximately 70% and 30% were recovered in the above‐ and below‐ground plant parts, respectively, for both forage species. Atom % ¹⁵N was similar for the red clover and alfalfa for each of the above‐ground plant parts and was slightly lower in the crown and roots for the red clover than for the alfalfa. Values of atom % ¹⁵N ranged from 0.5 for fine roots to 1.5 for leaves above 0.20 m from the ground. Labeling of the plant material was not uniform between plant parts but was adequate for many studies of N transfer to a succeeding crop.     

Iron‐Enriched Azolla as a slow‐release biofertilizer for cucumber plants grown in a hydroponic system

The unique ability of dried plant residues Azolla to adsorb iron (Fe) was employed to formulate and test an organic Fe biofertilizer. A simplified experimental system was established to examine the effectiveness of Fe‐enriched Azolla as a source of Fe for the remedy of Fe‐deficient plants. The optimal Fe‐enrichment level needed to achieve a complete recovery of starved plant by the Fe‐Azolla complex was tested using a bioassay system of hydroponically grown cucumbers. Dried Azolla plants were mixed a with a solution of ferrous sulfate (FeSO₄) at pH 2.0, rinsed, and dried to form organic, compact material containing 4% (w/w) Fe bound to Azolla. The Fe‐Azolla complex was applied to the nutrient solutions of Fe‐deficient cucumber seedlings. Growth rates and development measurements as well as chlorophyll and the Fe‐containing catalase activity tests have been performed. The effect of the slowly released Fe in correcting Fe deficiency were followed for three weeks and compared with the efficiency of additions of several synthetic Fe chelates. Iron‐starved plants exhibited fast regreening of the chlorotic interveinal tissues after the addition of Fe‐Azolla complex to the nutrient solutions. Iron starvation decreased the activity of catalase. Iron‐treated‐starved plants exhibited recovery of catalase activity compared to the low level activity measured untreated Fe‐starved plants. Iron‐enriched Azolla treatment was found equivalent to Fe‐EDTA and Fe‐EDDHA. This study is the first step in our research program aimed to establish the application of Fe‐enriched Azolla as a bioagent for the benefit of Fe‐deficient crops.     

Is Direct Seeding a Biologically Viable Strategy for Restoring Forest Ecosystems? Evidences from a Meta‐analysis

Ecological restoration has become an important technique for mitigating the human impacts on natural vegetation. Planting seedlings is the most common approach to regain lost forest cover. However, these activities require a large economic investment. Direct seeding is considered a cheaper and easier alternative technique, in which tree seeds are introduced directly on the site rather than transplanting seedlings from nurseries. To evaluate the effectiveness of direct seeding, we conducted a comprehensive search of the literature using ‘restoration’, ‘direct seeding’ and ‘sowing’ as keywords, and we performed a meta‐analysis using 30 papers and 89 species. We used two different measures of restoration success: seed germination probability and success probability (the chance that a seed germinates and survives until the end of the experiment). In general, restoration attempts using direct‐seeding techniques were relatively unsuccessful. On average, seed germination and success probability were 0·239 and 0·114, respectively, and were not affected by climate, species successional group or the application of pre‐germinative treatments. Germination and success probability increased with seed size, and the use of physical protections resulted in a nearly twofold increase in germination probability, but this effect faded by the end of the experiments. Because of the low rate of seedling success, we suggest the use of direct seeding as a complementary technique to reduce restoration costs, particularly for species with large seeds and known high germination rates, but our results do not support direct seeding as a substitute for seedling planting. Copyright © 2015 John Wiley & Sons, Ltd.     

Can a mesotrophic grassland community be restored on a post-industrial sandy site with compost made from waste materials?

Restoration of sites degraded by industry to species-rich semi-natural vegetation communities is difficult; it usually involves the addition of soil ameliorants but excessive fertility may favour dominance by competitive species. In a field-experiment we tested the establishment of a biodiverse mesotrophic grassland community using different compost types (comprising of mixtures of waste materials), application rates and seeding (with species in the target community). Compost addition to the alkaline sandy substrate increased soil organic matter, nutrient content and water holding capacity (WHC), whilst decreasing pH. Over the first two growing seasons compost addition, (especially at a higher rate) increased total vegetation cover (from <20% to a maximum of 67%), although the cover of the target community remained below 20%. Seeding with target species greatly increased their establishment on compost-treated plots, demonstrating its value for restoration of mesotrophic grassland communities in such sites lacking a local seed source. Five soil properties accounted for 46% of the variation in target species density: negative correlations with soil pH and %N, and positive correlations with electrical conductivity (EC), %C, and WHC. For this mesotrophic grassland community, high EC and WHC and low pH were most important for forb species and high %C for grasses. Overall, %C was the soil property that best explained variation in the early restoration success of different compost types and application rates; pH and EC were also correlated with the rate of vegetation establishment and available-P was linked to plant community composition. While a longer time period is needed to judge the sustainability of the outcome, this demonstrates the potential to refine compost properties for restoration of biodiversity.     

近60 a来淮河流域干旱变化特征

[目的]研究淮河流域近60年来干旱的变化特征,为以后防旱抗灾提供一定的参考。[方法]利用WAP(weight average of precipitation)指数法、空间Kriging法、小波分析等方法对淮河流域干旱变化时空特征进行分析。[结果]春季WAP指数在21世纪初下降幅度较大,易发生春旱,冬季WAP指数在1980年以后明显增加,冬旱有所减轻;年均WAP指数表征的干旱存在2~3a的主周期和6~7a的次主周期;在空间上,WAP指数大致由东南向西北递减,干旱程度由东南向西北逐渐增大。[结论]WAP指数能够很好地表征淮河流域干旱发生的时间和空间特征。     

近51 a青藏高原雪灾时空分布特征

选取青藏高原地区62个气象站点1961-2011年(普兰、改则为1973-2011年)逐日、逐月气温和降水量等气象资料,利用统计方法和空间Kriging插值方法研究青藏高原地区雪灾时间发生趋势和空间分布特征。结果表明,青藏高原近51 a雪灾频次呈增长趋势,雪灾发生站次不断增多,尤其是90年代以来增加趋势更为显著;初春为雪灾多发季节,前冬其次,后冬最少;雪灾发生频次空间分布很不均匀,雪灾发生较多区域,轻、中、重度雪灾都频繁发生,这些地区主要位于高原中部和高原东南部边缘。     

Nitrate‐nitrogen determination—a critical review

Abstract

This paper reviews the published methods of nitrate‐nitrogen (NO₃‐N) determination with the objective to assess their applicability to soil and plant tissue anarysis. The methods are separated into three categories on the basis of the analytical approach utilized for NO₃‐N determination. Strengths and weaknesses of the methods are discussed. The first analytical approach utilitizes direct measurement of NO₃‐N by the following methods: (a) colorimetric (after a color producing reaction with NO₃‐N), (b) potentiometric, (c) absorption of UV radiation by NO₃‐N in a complex matrix, (d) transnitration of salicylic acid, and (e) chromatographic (separation and measurement of NO₃‐N) methods. The second approach is based on the reduction of NO₃‐N to nitrite‐nitrogen (NO₂‐N), ammonium‐nitrogen (NH₄‐N), or nitric oxide and measurement of the reduction product. When NO₃‐N is reduced to NO₂‐N, the measurement may be achieved by (a) colorimetric, (b) fluorimetric, (c) coulometric, and (d) catalytic kinetic methods. When NO₃‐N is reduced to NH₄‐N, the measurement is done by (a) colorimetric (after a color producing reaction with NH₄), (b) potentiometric, (c) steam distillation, and (d) gas diffussion conductimetric methods. A chemiluminescence detection method is utilized when NO₃‐N is reduced to nitric oxide. The third approach determines NO₃‐N concentration by measuring the change in the concentration of the chemical species that react with NO₃‐N and form a complex.