Genotypic variation in grain cadmium concentration of lowland rice

Cadmium (Cd) contamination of paddy rice soils is commonly observed in the Yangtse River Delta, China. Large Cd uptake by rice plants and its translocation into the grains can entail human‐health risks. Genotypic variations in Cd uptake and a differential Cd partitioning into grains will be the basis for developing a rice screening or breeding tool for low grain Cd. A field experiment, conducted at the experimental farm of Jiaxing, Zhejiang province from 2002 to 2004, compared 38 rice genotypes of different types (indica vs. japonica) collected from the Yangtse River Delta. The results showed large differences in Cd concentrations in straw, brown rice, and grain chaff among the rice genotypes grown on Cd‐contaminated soil. Concentrations in brown rice ranged from 0.06 to 0.99 mg Cd kg^–1. The total Cd uptake in brown rice varied between 0.96 and 28.58 μg plant ^{– 1}. In general, indica‐type cultivars accumulated significantly more Cd than the japonica‐type cultivars. The Cd concentration in straw was highly correlated with that in brown rice. While significant differences in the Cd‐partitioning ratio (% share of total Cd uptake found in brown rice) among rice genotypes were observed, these were not correlated with Cd concentration of brown rice. This indicates that the Cd accumulation in rice grains appears to be governed mainly by the Cd uptake by the plant and probably not by differential Cd partitioning. The large genotypic variation suggests the possibility to lower the Cd content of rice by genotype selection. The development of such breeding tools should focus on low Cd uptake rather than Cd partitioning between straw and grain.     

Soil amino acid composition quantified by acid hydrolysis and anion chromatography-pulsed amperometry

Soil organic N accounts for 95-98% of the total soil N content with amino acids (AAs) and amino sugars (ASs) identified as the major soil organic N compounds, but traditional 6 M HCl with reflux or sealed digestions for 24 h and various detection systems have accounted for only 30-40% of soil total N content as AA-N. This study compared traditional HCl extraction methodology with methanesulfonic acid (MSA) hydrolysis and nonderivatized AA and AS quantification by ion chromatography with pulsed amperometric detection for determination of the AA composition of plant litter and soils. MSA (4 M) gave AA-N recovery comparable to or better than 6 M HCl for plant AA digestions (16 h, 121 degrees C, 104 kPa). Use of 4 M MSA (0.5-1.5 h, 136 degrees C, 112 kPa) increased the total recovery of organic N as AAs, ASs, and NH(4)(+) by 46% from soils (n = 22) compared with 6 M HCl (12 h, 110 degrees C, reflux) with a MSA recovery rate of 85.6% of the total N content (n = 22 soils). The shorter MSA soil digestions (0.5-1.5 h) suggested that the majority of soil organic N was not present as protein forms found in plant litter analysis (16 h of digestion). MSA ion chromatographic analysis for soil AA/AS composition is a robust nonderivatization method requiring little sample preparation that can distinguish between small changes in soil AA composition during one growing season due to vegetation and tillage managements.     

Feasibility of using FGD gypsum to conserve water and reduce erosion from an agricultural soil in Georgia

Crop production in Georgia and the Southeastern U.S. can be limited by water. Highly-weathered, drought-prone soils are susceptible to runoff and erosion. Rainfall patterns generate runoff producing storms followed by extended periods of drought during the crop growing season. Thus, supplemental irrigation is often needed to sustain profitable crop production. Increased water retention and soil conservation would efficiently improve water use and reduce irrigation amounts/costs and sedimentation, and sustain productive farm land, thus improving producer's profit margin. Soil amendments, such as flue gas desulfurization (FGD) gypsum, have been shown to retain rainfall and/or irrigation water through increased infiltration while decreasing runoff (R) and sediment (E). Objectives were to quantify rainfall partitioning and sediment delivery improvements with surface applied FGD gypsum from an Ultisol managed to conventional till (CT) and to assess the feasibility of using FGD gypsum on agricultural land in southern Georgia. A field study (Faceville loamy sand, Typic Kandiudult) was established (2006, 2007) near Dawson, GA managed to CT, irrigated cotton (Gossypium hirsutum L.). FGD gypsum application rates evaluated were 0, 1.1, 2.2, 4.5, and 9 Mg ha^− 1. Gypsum treatments and simulated rainfall (50 mm h^− 1 for 1 h) were applied to 2-m wide × 3-m long field plots (n = 3). Runoff and E were measured from each 6-m² plot (slope = 1%). FGD gypsum plots averaged 26% more infiltration (INF), 40% less R, 58% less E, 27% lower maximum R rates (R_max), and 2 times lower maximum E rates (E_max) than control plots. Values of INF and water for crop use increased, and R, E, R_max, and E_max decreased as FGD gypsum application rate increased. Values of INF, R, E, R_max, and E_max for 9 Mg ha^− 1 plots were as much as 17% greater, 35% less, 1.9 times less, 35% less, and 1.9 times less than those from other FGD gypsum plots, respectively; and 40% greater, 40% less, 2.2 times less, 52% less, and 2.9 times less than those from control plots, respectively. Applying FGD gypsum to agricultural lands is a cost-effective management practice for producers in Georgia that beneficially impacts natural resource conservation, producer profit margins, and environmental quality. Agriculture in the Southeast provides a viable market for the electric power industry to convert disposal costs of FGD gypsum into a profitable commodity.     

河蟹养殖自动作业船导航控制系统设计与测试

针对河蟹养殖过程中存在的水草清理难度大、喂料投饵不均匀、人力成本高等问题,该文设计了一种基于ARM(advanced RISC machine)和GPS/INS(global positioning system/inertial navigation system)组合导航的多功能全自动河蟹养殖作业船导航控制系统。该系统由明轮驱动船、ARM主控制器、GPS/INS组合导航装置等组成。为降低传统的基于有限目标点航道位置计算方法的复杂度并减小船体偏离航道的误差,该文提出了一种基于实时插点的航道位置计算方法,实时地解算出当前时刻的目标位置,并设计了相应的转弯及航道切换策略。针对明轮船具有非线性、大时滞、欠阻尼的运动特点,设计了基于模糊PID(proportion integration differentiation)的航向、航速双闭环运动控制算法;基于嵌入式Linux操作系统,设计了船载子系统软件,并编写了上位机监控程序对船载子系统的运行状态进行实时监控。利用河蟹养殖作业船试验平台进行了航速及自动导航试验,并对有限目标点和实时插点的航道位置计算方法的控制效果进行了对比。试验结果表明:船体速度响应较快,超调量不超过5%,稳态误差可控制在3%以内;采用有限点的航道位置计算方法时,船体在转弯与直行时偏离航道的最大误差分别为2.12和1.52m;采用实时插点的航道位置计算方法时,船体在转弯与直行时偏离航道的最大误差分别为0.36和0.09m,分别下降了83.02%和94.08%,船体的控制精度得到了全面的改善。该文可以为多功能河蟹养殖作业船的研究提供重要参考。     

Abscisic acid improves tomato fruit quality by increasing soluble sugar concentrations

Abscisic acid (ABA) is crucial in fruit maturation and senescence and is considered as the other ripening control factor other than ethylene. Important components in ripening fruit are soluble sugars, which make the fruit sweeter and carotenoids, important flavor compounds in ripened fruit. The purpose of this study was to examine the effects of foliar ABA and calcium (Ca) fertilizer treatments (individually and in combination) on determinate beef-steak greenhouse tomato (Solanum lycopersicum) leaf chlorophylls and carotenoids, fruit carotenoids, and soluble sugar concentrations. Foliar spray treatment of 500 mg L^?1 ABA increased zeaxanthin (ZEA) and β-carotene (BC) in tomato leaf tissue. Increases in Ca fertilizer treatments significantly decreased tomato leaf violaxanthin (VIO), but no effect on other carotenoids. The application of 500 mg L^?1 ABA foliar spray significantly increased glucose and fructose concentrations in tomato fruit tissue. Foliar application of ABA treatments can increase overall chlorophyll, carotenoid content, and fruit quality.     

Nutrient accumulation in leaf tissue of rapid‐cycling brassuca oleracea responds to increasing sodium selenate concentrations

Brassica oleracea L. are important economic vegetables, and are capable of selenium (Se) enrichment to enhance human nutrition and health. Because Se enrichment may influence the nutrient balance of this crop, a study was done to test the effects of selenate‐Se on plant nutrients. Plants of a rapid‐cycling B. oleracea population were grown in nutrient solutions amended with Na₂SeO₄at 0.0, 3.0, 6.0, and 9.0 mg L^‐1. Leaf tissue was then analyzed for nutrient content. Boron (B) (P=0.01), iron (Fe) (P=0.01), and phosphorus (P) (P=0.01) content decreased, while Se (P=0.01), sulfur (S) (P=0.01), and potassium (K) content (P=0.01) increased with increasing selenate‐Se treatments. Significant quadratic responses were found for magnesium (P=0.01) and molybdenum (P=0.01). No significant differences in leaf fresh or dry weight were detected. Changes in plant nutrient content can be expected when Brassicas are enhanced for delivery of beneficial organic Se.     

Chemical Amendments and Process Controls To Reduce Ammonia Volatilization During In-House Composting

Composting inside high-rise, caged layer facilities can produce atmospheric ammonia (NH₃) concentrations exceeding standards for human and poultry health. Control measures that reduce NH₃ volatilization are necessary for in-house composting to be sustainable. Due to differences specific to in-house composting — low carbon to nitrogen ratios of composting material, continuous manure addition, and frequent turning — it is not known whether NH₃ control measures used previously for poultry manure will work. The objectives of this study were to evaluate various amendment and process controls on NH₃ produced during simulated in-house composting in the lab, and to evaluate select chemical control measures during composting inside a high-rise layer facility. Ten amendments (aluminum sulfate; chloride salts of aluminum, calcium, magnesium, and potassium; gypsum; sodium bisulfate; zeolite (clinoptilolite); straw; and cellulose) and four process controls (moisture; temperature; turning frequency; and particle size) were evaluated in lab incubations in 1 L vessels wherein samples of poultry manure compost were incubated to simulate composting. Vials of boric acid solution were used to capture NH₃ evolved during incubations. With the exception of zeolite and cellulose, all amendments reduced NH₃ capture. Low moisture and temperature also reduced NH₃ capture, although managing temperature and moisture to achieve low NH_g would adversely impact microbial activity and other desired benefits of composting. When evaluated inhouse, aluminum sulfate, calcium chloride and magnesium chloride did not reduce NH evolution from compost measured on three different dates with a gas sensor. Spatial variability along treated segments of windrow apparently masked amendment effects. At the end of a six-week composting cycle, total nitrogen content was higher in compost treated with aluminum sulfate than control or chloride salt treatments. Aluminum sulfate and process controls such as moisture content, carbon source and particle size have potential to reduce NH₃ loss from poultry manure composted inside high-rise layer structures. In-house compost management to reduce NH₃ volatilization must consider the cost of amendments, effectiveness, and impacts on the composting process.     

The effect of VRN1 genes on important agronomic traits in high‐yielding Canadian soft white spring wheat

For reproductive success, flowering time must synchronize with favourable environmental conditions. Vernalization genes play a major role in accelerating or delaying the time to flowering. We studied how different vernalization (VRN1) gene combinations alter days to flowering and maturity and consequently the effect on grain yield and other agronomic traits. The study focussed on the effect of the VRN1 gene series (Vrn‐A1, Vrn‐B1 and Vrn‐D1) and their combinations. The Vrn gene group Vrn‐A1a, Vrn‐B1, vrn‐D1 was the earliest to flower and mature, while Vrn‐A1b, Vrn‐B1, vrn‐D1 was the latest to flower. Spring wheat lines with vrn‐A1, Vrn‐B1, Vrn‐D1 were the highest yielding and matured at a similar time as those having vernalization genes Vrn‐A1a, Vrn‐B1 and Vrn‐D1. The findings of this study suggest that the presence of Vrn‐D1 has a direct or indirect role in producing higher grain yield. We therefore suggest the introduction of Vrn‐D1 allele into higher‐yielding classes within Canadian spring wheat germplasm.     

Flowering time in wheat (Triticum aestivum L.): a key factor for global adaptability

Wheat is one of the most widely cultivated crops and, being the staple diet of more than 40 countries, it plays an imperative role in food security. Wheat has remarkable genetic potential to synchronize its flowering time with favourable environmental conditions. This ability to time its flowering is a key factor for its global adaptability and enables wheat plant to produce satisfactory grain yield under very diverse temperature and soil moisture conditions. Vernalization (Vrn), photoperiod (Ppd) and earliness per se (Eps) are the three genetic systems controlling flowering time in wheat. The objective of this review is to provide comprehensive information on the physiological, molecular and biological aspects of the three genetic constituents of flowering and maturity time in wheat. Reviews written in the past have covered either one of the aspects; and generally focused on one of the three genetic constituents of the flowering time. The current review provides (a) a detailed overview of all three gene systems (vernalization, photoperiod and earliness per se) controlling flowering time, (b) details of the primer sequences, their annealing temperatures and expected amplicon sizes for all known markers of detecting vernalization and photoperiod alleles, and (c) an up to date list of QTLs affecting flowering and/or maturity time in wheat.