Maintenance of Vigour and Viability of Stored Pea (Pisum sativum L.) Seeds

To determine the most efficacious midstorage hydration-dehydration treatment for preservation of vigour and viability of stored pea seeds ( Pisum sativum L.), cultivar Bonneville , three methods viz., soaking-drying, moisture equilibration-drying and moist sand conditioning-drying each at varying durations were evaluated. Irrespective of the durations of treatment, soaking-drying proved injurious. Though all durations of moisture equilibration excepting and 120 h outperformed the control, yet 48 h proved to be the best. Preconditioning with moist sand (5 % moisture content) with seed at a ratio of 1: 2.5 for different durations revealed 48 h to be the optimum, 72–96 h to be innocuous and thereafter injurious. Maintenance of membrane integrity and counteraction of lipid peroxidation may be the possible reasons for such beneficial effects.     

Rapid and Sensitive Analytical Method for Simultaneous Determination of Imidacloprid and Thiamethoxam Residues in Soils of Sugarcane Ecosystem by Reversed-Phase HPLC

A rapid, simple, sensitive and cost-effective analytical method has been standardised to determine the residues of imidacloprid and thiamethoxam in soil. This method does not require any cleanup with costly sorbents. The recoveries of imidacloprid and thiamethoxam obtained in this no-cleanup method were on par with the protocol involving primary?Csecondary amine-based cleanup. This method requires less volume of solvent (20?mL of acetonitrile/sample) and is suitable for high throughput analyses involving large number of samples. The limit of quantification of the method was 0.01???g/g. Dissipation kinetics of imidacloprid and thiamethoxam in the soils of sugarcane ecosystem was studied by adopting this rapid method. The half-life of imidacloprid and thiamethoxam was 9.07 and 6.22?days when applied at 70 and 100?g a.i./ha, respectively. The dissipation of both the neonicotinoids followed first-order kinetics with good fit.     

Effects of copper rates and soil ph on growth and nutrient uptake by citrus seedlings

Abstract

Soil properties, primarily pH and organic matter, influence phytotoxicity of copper (Cu). A pot experiment was conducted to evaluate the effects of copper additions (0, 25, 50, 100, 200, and 400 mg kg^?1) to three different soils [Myakka fine sand (pH 5.7), Candler fine sand (pH 6.5), and Oldsmar fine sand (pH 8.2)] on growth, and uptake of phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), and copper (Cu) by Swingle Citrumelo (SC) seedlings. In unamended soils, the seedling growth was similar in the Myakka and Candler fine sands (pH 5.7 to 6.5), but was significantly greater in the Oldsmar fine sand (pH 8.2). Increasing the rate of Cu from 0 to 400 mg kg^?1 decreased the soil pH by 0.98 unit in the Candler fine sand, by 1.57 pH unit in the Myakka fine sand, and negligible effects on the pH of the Oldsmar fine sand. The growth of SC seedlings decreased significantly with an increase in Cu rates in the Myakka and Candler fine sands, but not in the Oldsmar fine sand. The Cu concentration in the leaves and roots increased substantially with an increase in the Cu rate applied to the Candler and Myakka fine sands while the effect was marginal in the Oldsmar fine sand. The above effect was more pronounced on the Cu concentration in the roots than in the leaves. Increased rate of Cu application decreased the uptake of P, Mg, Ca, and K in the roots and leaves of the seedlings grown in the Myakka and Candler fine sands but not in the Oldsmar fine sand.     

Prevalence of peste des petits ruminants among sheep and goats in India

This study measured the clinical prevalence of peste des petits ruminants (PPR) among sheep and goats in India between 2003 and 2009 by analyzing clinical samples from suspected cases of PPR that were submitted to the Rinderpest and Allied Disease Laboratory, Division of Virology, IVRI, Mukteswar for PPR diagnosis. PPR outbreaks were confirmed by detecting PPR virus (PPRV)-specific antigen in the clinical samples. Clinical samples (blood, nasal swabs, spleen, lymph node, kidney, liver, intestine, and pooled tissue materials) were taken from a total of 592 sheep and 912 goats in different states of India and screened for the presence of PPRV antigen using a monoclonal antibody-based sandwich ELISA kit. A total of 20, 38, and 11 laboratory-confirmed PPR outbreaks occurred among sheep, goat, and combined sheep and goat populations, respectively. Our findings provide evidence of widespread PPR endemicity in India. The underlying reasons could be variations in husbandry practices in different geographical regions, agro-climatic conditions, and livestock migration. Furthermore, decrease in the number of PPR outbreaks over time might be due to the effectiveness of current live PPR vaccines and timely vaccination of target species. Vaccination against PPR has been practiced in India since 2002 to control this disease.     

Nitrogen best management practice for citrus trees: I. Fruit yield,quality, and leaf nutritional status

Elevated levels of nitrate-nitrogen (NO₃-N) in the surficial aquifer above the drinking water quality standard, i.e. maximum contaminant limit (MCL; 10 mg L⁻¹), have been reported in some part of central Florida citrus production regions. Soils in this region are very sandy (sand content >95%), hence are vulnerable to leaching of soluble nutrients and chemicals below the rooting depth of the trees. The objective of this research was to develop N and irrigation best management practices for citrus in sandy soils to maintain optimal crop yield and quality, and to minimize potential leaching of nitrate below the root zone. Six years of field experiment was conducted in a high productive (mean fruit yield > 80 Mg ha⁻¹yr⁻¹) >20-year-old ‘Hamlin’ orange trees [Citrus sinensis (L.) Osbeck] on ‘Cleopatra mandarin’ (Citrus reticulata Blanco) rootstock grown on a well drained Tavares fine sand (hyperthermic, uncoated, Typic Quartzipsamments) in Highland county, FL. Nitrogen rates ranged from 112 to 280 kg ha⁻¹ yr⁻¹ applied as fertigation (FRT), water soluble granular (WSG), 50:50 mix of FRT and WSG, and controlled-release fertilizer (CRF). Tensiometers were used to monitor the soil water content as a basis to schedule optimal irrigation. Fruit yield response over the entire range of N rates was greater for the FRT and WSG sources as compared to that for the WSG + FRT or CRF sources. Using the regression analysis of the fruit yield in relation to N rate, the optimum N rate appeared to be at 260 kg ha⁻¹ yr⁻¹. Based on fruit production response in this study, the N requirement for production of 1 Mg of fruit varied from 2.2 to 2.6 kg across four N sources. This study demonstrated an increased N uptake efficiency, as a result of best management of N and irrigation applications. The optimal N and K concentration in the 4–6-month-old spring flush leaves were 26–30, and 15–18 g kg⁻¹, respectively. However, fruit yield response showed no significant relationship with concentrations of P in the 4–6-month-old spring flush leaves over a range of 0.8–2.4 g kg⁻¹. The results of fate and transport of N in soil and in soil solution with application of different rates and sources of N, and components of citrus tree N budget, are reported in a companion paper.     

Use of the Urease Inhibitor N-(n-BUTYL)-Thiophosphoric Triamide Decreased Nitrogen Leaching from Urea in a Fine Sandy Soil

Water, Air, &; Soil Pollution - Application of soluble forms of nitrogen (N) fertilizers to citrus trees in sandy soils of central Florida may cause leaching of NO 3 ? below the rooting...     

Fruit nutrient accumulation of four orange varieties during fruit development 1

Evaluation of nutrient accumulation trends in fruit during fruit development and nutrient status in the leaves are important components defining nutrient requirements. Such nutrient demand should be met by nutrient supply in order to develop optimal rate and timing of fertilizer application. In a 3‐year study the citrus (orange) varieties, ‘Valencia’, ‘Parson Brown’, ‘Hamlin’, and ‘Sunburst’ were fertilized with either 168, 224, or 280 kg N ha^‐1 yr^‐1 as a broadcast application of N:P:K dry soluble granular fertilizer. These rates did not significantly affect the fruit nutrient status, juice quality, or nutrients concentrations in the spring flush. The concentrations of nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg) in the fruit decreased with their enlargement during June through November. However, micronutrient concentrations in the fruits increased from June through August or September and then decreased. Fruit dry weight was greatest in ‘Valencia’ followed by ‘Hamlin’, ‘Parson Brown’, and ‘Sunburst’ varieties. Soluble solids concentration (SSC) were higher in ‘Valencia’ and ‘Sunburst’ fruit than in the other two varieties. Other juice quality parameters were not significantly different among the varieties. This study indicated non‐significant influence of fertilizer rates on concentrations of various mineral elements in 6‐month‐old spring flush with most of those concentrations within the optimal ranges.     

Assessment of Soil Phosphorus Balance: Application of Dynamic Nutrient Balance Approach to South Indian Agricultural Farming System

This study applied a dynamic nutrient balance method to estimate a stock of soil phosphorus and its usage pattern. We used panel data of published agricultural production, fertilizers supply, and livestock population to assess the net inflows, outflows, and stock of phosphorus in 19 regions of Tamil Nadu in the years 1990–2012. The dynamic model supported us to find pattern of phosphorus stocks and flow over the period, and more importantly, the total phosphorus outflow breakdown into removal by crop, soil, air, and water. This model simultaneously assesses the phosphorus stock, flows, and outflows inclusion of time factor, and thus it is one of robust agricultural environmental indicators. This paper will support the farmers and stakeholders to take an appropriate policy according to status of nutrient in the estimated agricultural regions.     

Best Nitrogen and Irrigation Management Practices for Citrus Production in Sandy Soils

Drinking water monitoring data have indicated anincrease in nitrate-nitrogen (NO₃-N) concentration ingroundwater in some parts of the citrus production region ofFlorida. A proactive, incentive-based program of developingcrop-specific best management practices (BMP) began with theFlorida N-BMP legislation passed in 1994. A combination ofcareful irrigation and nitrogen (N) management is needed toimprove N uptake efficiency and to minimize potential leaching ofnitrate (NO₃-N) to the groundwater. An improved Nmanagement practice is considered as a BMP, only if that practiceis proved to decrease NO₃-N leaching into groundwater incommercial groves without adversely impacting the economics ofproduction. Therefore, long-term evaluation of horticulturalresponses as well as monitoring of groundwater NO₃-N wereconducted in five commercial groves representing different soiltypes, citrus variety and rootstock, tree age, and culturalpractices to determine the impact of changes in N managementand/or irrigation scheduling. Groundwater NO₃-N, leafnutrient concentrations, fruit yield and fruit quality weremonitored for 15 months under the growers' routine managementand, subsequently for 48 months, with improved N and irrigationmanagement practices. The N management practices evaluated inthis study included broadcast application of a combination ofwater soluble and slow release granular products, fertigation,and a combination of foliar application and fertigation. Irrigation management was improved by using tensiometer set pointof 10 and 15 cbar. This article presents the fruit yield, andconcentrations of N, P, K in six-month spring flush during thestudy period. The study showed that 5 to 8 yr old Valenciatrees on Volkamar lemon rootstock produced high quality fruit inthe range of 59 to 81 Mg ha^-1 with 168 kg N ha^-1 asfertigation combined with improved irrigation scheduling. Fruityield of 36 yr old Valencia orange trees on Rough lemonrootstock was greater with application of 180 kg N ha^-1 yr^-1 as fertigation compared to that of the trees whichreceived a similar rate of N as three broadcast applications ofgranular product. Fertilizer program comprising three foliarapplications of N using low biuret urea to deliver 66 kg N ha^-1 yr^-1 and an additional 76 kg N ha^-1yr^-1as fertigation was the most effective for decreasing the surficialgroundwater NO₃-N while maintaining optimal fruit productionand nutritional status of the leaves. This study demonstratedthat economically and technically feasible N-BMPs can bedeveloped for citrus grown on sandy soils with a combination ofimproved N management and irrigation scheduling.     

Incinerated Sewage Sludge Products as Amendments for Agricultural Soils: Leaching and Plant Uptake of Trace Elements

Preliminary leaching column and greenhouse plant uptake studies were conducted in two soils with contrasting characteristics amended with varying rates (0 to 148.3 Mg ha^?1) of incinerated sewage sludge (ISS) and weathered sewage sludge (WISS) to estimate the leaching losses of trace elements from the soils amended with incinerated sewage sludge by products and to evaluate the uptake and accumulation of these elements in various parts of Sorghum vulgaris var. sudanense Hitche. (“Sorgrass''), a Sorghum-Sudan grass hybrid. Results of this study indicated that leaching of Cr, Cd, Zn, Cu, Ni, Fe and Mn from soils amended with ISS and WISS increased with increasing rates of amendment. Results of the leaching column study further revealed greater leaching losses from coarse-textured soil compared to medium-textured soil and also from ISS amended soils than with WISS amended soils. Results further suggested that the type of element and the interaction between the element and soil properties affected the leachability of various trace elements. The uptake study indicated uptake and accumulation of trace elements by plant parts increased with increasing rates of amendments. Greater plant uptake and accumulation of trace elements were observed in plant parts grown in soils amended with ISS compared to that of WISS. Results also indicated a greater accumulation of trace elements in below ground part of the plants (roots) compared to that was observed in above ground parts (shoots). Limited data obtained from this one season preliminary studies demonstrated that incinerated sewage sludge products from wastewater treatment plants could be used as soil amendments at low application (no more than 24.7 Mg ha^?1) for optimum plant growth, and dry matter yield without resulting in substantial accumulation of metals in plant parts at concentrations above the recommended critical limits and without causing significant leaching losses of various trace elements. It is imperative that long-term field studies are necessary to evaluate the long-term impact of using these new products in leaching and accumulation of various trace elements in plants and soils.