The effects of deficit irrigation on nitrogen consumption,yield,and quality in drip irrigated grafted and ungrafted watermelon

The aim of this study is to determine the effects of deficit irrigation on nitrogen consumption,yield,and quality in grafted and ungrafted watermelon.The study was conducted in Cukurova region,Eastern Mediterranean,Turkey,between 2006 and 2008,and employed 3 irrigation rates(full irrigation(l_(100)) with no stress,moderate irrigation(Dl_(70)),and low irrigation(Dl_(50));Dl_(70) and Dl_(50) were considered deficit irrigation) on grafted(CTJ,Crimson Tide+Jumbo) and the ungrafted(CT,Crimson Tide) watermelon.The amount of irrigation water(IR) applied to the study plots were calculated based on cumulative pan evaporation that occurred during the irrigation intervals.Nitrogen consumption was 16%lower in CTJ plants than in CT plants.On the other hand,consumption of nitrogen was 28%higher in Dl_(50) plants than in Dl_(70) plants while it was 23%higher in Dl_(50) plants than in l_(100) plants.By grafting,the average amount of nitrogen content in seeds,pulps and peels for CTJ was 30,43 and 56%more than those of CT,respectively.The yield and the quality were not significantly affected by the deficit irrigation.In this respect,grafting of watermelon gave higher yield,but,it had a slight effect on fruit quality.The highest yield values of 16.90 and 19.32 kg plant~(-1) in 2008 were obtained with l_(100)and in CTJ plants,respectively.However,Dl_(50) treatment could be taken into account for the development of reduced irrigation strategies in semiarid regions where irrigation water supplies are limited.Additionally,the yield increased by applying CTJ treatment to the watermelon production.     

Modified 2,2-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (abts) method to measure antioxidant capacity of Selected small fruits and comparison to ferric reducing antioxidant power (FRAP) and 2,2'-diphenyl-1-picrylhydrazyl (DPPH) methods

The measurement of antioxidant capacity in fruits differs from that of other biological samples due to their low pH and very low lipophilic antioxidant capacity. In this report, we present a modified 2,2-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) method for fruits and compare its performance with the other commonly used antioxidant methods of 2,2'-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP). The antioxidant capacity and reaction kinetics of four phenolic compounds, two antioxidant standards, and five fruits were also investigated. The modified ABTS method prepared at a pH of 4.5 with sodium acetate buffer is highly stable and easily applied to fruit samples as compared to the standard (pH 7.4) version. The measured antioxidant capacity of samples varied with the assay method used, pH, and time of reaction. Traditional antioxidant standards (trolox, ascorbic acid) displayed stable, simple reaction kinetics, which allowed end point analysis with all of assays. Of the phenolic compounds examined, chlorogenic and caffeic acids exhibited the most complex reaction kinetics and reaction rates that precluded end point analysis while gallic acid and quercetin reached stable end points. All fruit extracts exhibited complex and varied kinetics and required long reaction times to approach an end point. Because the antioxidant capacity of fruit extracts is a function of the array of individual antioxidants present, accurate comparisons among fruit samples require that reaction times be standardized and of sufficient length to reach steady state conditions and that more than one assay be used to describe the total antioxidant activity of fruit samples.     

Unravelling the diversity and assemblage of phytoplankton in homestead ponds of central coastal belt,Bangladesh

Homestead ponds may offer an ideal opportunity in contribution to household income, fish consumption through fish culture. Phytoplankton plays a key indicator in pond productivity. However, the phytoplankton communities in the homestead ponds are nearly undetermined in Bangladesh. This study summarizes the phytoplankton diversity, assemblage and ecological parameters of the homestead ponds in central coastal belt, Bangladesh, based on two seasons. The results revealed that significant differences (p < .05) were found in pH, DO, conductivity, TDS, nitrates, phosphates and sulphates except temperature in monsoon, and transparency in both seasons. A total of 34 phytoplankton genera representatives of five major groups were recorded such as Euglenophyceae (41.5%), Chlorophyceae (30.5%), Cyanophyceae (13%), Dinophyceae (10%) and Bacillariophyceae (5%). A significant difference (p < .05) in phytoplankton abundance was found in both seasons with the highest mean of 186.13 ± 129.34 × 10⁴ cells L^?1 in monsoon and the lowest mean of 144.40 ± 107.26 × 10⁴ cells L^?1 during winter. The diversity (H'), evenness (J'), richness (d) and dominance (D) ranged from 1.62 to 2.47, 0.52 to 0.97, 0.37 to 1.15 and 0.10 to 0.28 respectively. Based on SIMPER, the most dominant (>10%) genera for dissimilation within stations and seasons were Euglena spp., Phacus spp., Chlorella spp., Strombomonas spp. and Peridinium spp. ANOSIM results stated that 12 genera of phytoplankton were significant contributors based on average dissimilarity. Pearson's correlation coefficient and canonical correspondence analysis (CCA) revealed that phytoplankton abundance, diversity and community were mainly governed by transparency, dissolved oxygen and nitrates.     

Spatially discriminating Russian wheat aphid induced plant stress from other wheat stressing factors

The Russian wheat aphid (RWA) Diuraphis noxia (Mordvilko) is a major pest of winter wheat and barley in the United States. RWA induces stress to the wheat crop by damaging plant foliage, lowering the greenness of plants, and affecting productivity. The utilization of multispectral remote sensing is effective at detecting plant stress in agricultural crops. Stress to wheat plants detected in fields can be caused by several factors that can vary spatially in their presence and intensity across a field. Stress can result from factors such as nutrient deficiency, drought, diseases, and pests that can occur individually or collectively. The present study investigated the potential of using spatial pattern metrics derived from multispectral images in combination with topographic and edaphic variables to identify a set of variables to differentiate the stress induced by RWA from other stress causing factors. A discriminant function analysis was applied to 15 discriminating variables. A set of 13 variables were retained to develop a model to differentiate the three types of stress. Overall, 97 percent of patches of stress used to validate the model were correctly categorized. Stressed patches caused by RWA were 98 percent correctly classified, patches caused by drought were 94 percent correctly classified, and patches caused by agronomic conditions were 99 correctly classified. It is possible to discriminate stress induced by RWA from other stress causing factors in multispectral data when spatial attributes of the stress causing factors are incorporated in the analysis.     

Factors influencing biomass and carbon storage potential of different land use systems along an elevational gradient in temperate northwestern Himalaya

We observed the influence of five different altitudes and prevailing agro ecosystems on biomass and carbon sequestration potential in Kullu district of Himachal Pradesh, India. The study area had five prevailing land uses viz., agriculture, agro-horticulture, horticulture, silvi-pasture, and forest at four elevations representing about 1 °C temperature change. The results showed that maximum total biomass of 404.35 Mg C ha^?1 was accumulated by forest landuse and followed a decreasing trend in the order as forest > silvi-pasture > agro-horticulture > horticulture > agriculture. Similar trends were also seen with respect to biomass carbon (C) density and C-sequestration potential of different land uses. Biomass and carbon density potential enhanced with the increase in the altitudinal ranges from 1100–1400 to 2000–2300 m a.s.l. But, the rate of C-sequestration potential enhanced from 1100 to 2000 m and declined at 2000–2300 m a.s.l. Maximum carbon density (393.29 Mg C ha^?1) of both plant as well as soil was displayed by the forest-based land use systems situated at an altitudinal gradient of 2000–2300 m a.s.l. The rate of C-sequestration was maximum (2.17 Mg ha^?1) in the agro-horticulture at 2000–2300 m a.s.l. This study brings out the potential of different land use systems influenced by varying factors on their C-sequestration potential in western Himalayan elevation gradient, thereby providing useful information for effective management in a climate change mitigation and carbon budget.     

Quantification of organic carbon and primary nutrients in litter and soil in a foothill forest plantation of eastern Himalaya

The present study was an effort to understand the amount of litter fall and its subsequent decomposition and quantify the release of available nutrients and soil physicochemical characteristics in plantations of four forest tree species(Lagerstroemia parviflora, Tectona grandis, Shorea robusta and Michelia champaca) in the Chilapatta Reserve Forest of the Cooch Behar Wildlife Division in the Terai zone of West Bengal, India. The most litter(5.61 Mg ha~(-1))was produced by T. grandis plantation and the least(4.72 Mg ha~(-1)) by L. parviflora. The material turnover rate to the soil through decomposition from total litter was fastest during the first quarter of the year and subsequently decreased during the next two quarters. The material turnover rate was only 1 year, which indicates that more than90% of the total litter produced decomposed within a year.The available primary nutrient content in litter varied across the four plantations over the year. The plantations generally did not significantly influence the soil physical characteristics but did significantly influence the availability of primary nutrients and organic carbon at two depths(1–15 and16–30 cm) over the year. The availability of soil primary nutrients in the four plantations also increased gradually from the first quarter of the year to the third quarter and then decreased during the last quarter to the same level as in the first quarter of the year at both depths. The availability for soil organic carbon in the plantations followed a similar trend. The amount of litter produced and the material turnover in the soil in the different plantations differed, influencing the nutrient availability and organic carbon at the plantations. The amount of soil organic carbon was highest for T. grandis(2.52 Mg ha~(-1)) and lowest for L. parviflora(2.12 Mg ha~(-1)). Litter is the source of soil organic matter,and more the litter that is produced by the plantations, the higher will be the content and amount of soil organic carbon in the plantation.     

Spatial variability of soil penetration resistance in an alluvial delta plain under different land uses in middle Black Sea Region of Turkey

The aim of this study was to analyse the soil compaction and its spatial variability on an alluvial plain in K?z?l?rmak River Delta in Turkey, which is an important agricultural area where vegetable, rice, cereals and other crops have been grown under conventional tillage and irrigation over a long period. Penetration resistance (PR) was measured at 5 cm depth intervals between 0 and 40 cm soil depth, and gravimetric water content (GWC), field capacity (FC) and texture were determined for 0–20 cm and 20–40 cm. Penetration resistance values in some parts of the area were higher than the critical value for root growth limitation, the mean PR values at all depths were considerably lower than the critical value despite a relative increase in PR with soil depth. The areas with values greater than 3.0 MPa, except for 0–5 cm, were generally located in the fields with high sand content, especially near the K?z?l?rmak River. In contrast, for 0–5 cm, the areas with PR greater than 3.0 MPa, which is the value accepted for root growth limitation, were usually located in the west and northwest of the study area and had a high clay content.     

Occurrence of Viruses Affecting Potato Crops in Khartoum State-Sudan

The incidence of Alfalfa mosaic virus (AMV), Potato leafroll virus (PLRV), and Potato virus Y (PVY) in potato crops derived from various types of seed potatoes was assessed visually and confirmed by direct tissue blot immunoassay, over two winter growing seasons (1999/2000, 2000/2001) at three locations, Elnaiya, Elshehinab, and Shambat in Khartoum State, the main potato growing region in Sudan. Virus infection was most prevalent in 2000/2001. In general, crops grown directly from imported certified seed potatoes and from “improved seed”, produced in Sudan from imported basic seed, showed the lowest levels of PLRV and PVY compared with crops grown from Sudanese farm saved seed. For AMV, however, only crops grown directly from imported certified seed potatoes had low levels of AMV. Crop location also affected virus incidence, although this varied with year. For AMV, levels were similar at all locations in 1999/2000, but were greatest at Elnaiya in 2000/2001. For PVY, levels were greatest at Elnaiya in 1999/2000 and Shambat in 2000/2001. For PLRV, no symptoms were observed in 1999/2000 and virus levels were similar for all locations in 2000/2001. This study reports for the first time the occurrence of AMV in potatoes grown in Sudan.     

Insecticidal activity of (2<Emphasis Type="Italic">n</Emphasis>-octyl<Emphasis Type="Italic">cyclo</Emphasis>prop-1-enyl)-octanoic acid (I) against three Coleopteran stored product insects from <Emphasis Type="Italic">Sterculia foetida</Emphasis> (L.)

The insecticidal activities of the extracts, fractions, and pure compound of Sterculia foetida (L.) seeds were investigated against three major stored product pests, namely, Sitophilus oryzae (L.), Callosobruchus chinensis (L.), and Tribolium castaneum (H.), through contact and fumigation bioassay. Responses varied with test chemicals, insect species, exposure times, and doses individually. The biologically active constituent of the S. foetida seeds was characterized as a cyclopropene fatty acid structurally elucidated as (2n-octylcycloprop-1-enyl)-octanoic acid (I) by spectroscopic analysis. The filter paper application of, (2n-octylcycloprop-1-enyl)-octanoic acid (I) at 0.2 mg/cm² caused 100% mortality to all test insects 2 days after treatment (2 DAT). Among the chromatographic fractions, only the pure hexane-eluted fraction caused 100% mortality at 0.3 mg/cm² to S. oryzae and C. chinensis 2 DAT, while the dose required to obtain the same percentage of mortality with the crude seed extract was 0.6 mg/cm². Under all treatment conditions, T. castaneum exhibited less susceptibility, taking longer than the other insects to show symptoms of toxicity. In terms of fumigant activity, the compounds appeared to be more effective in a vapor form against all the three insects in closed containers compared with open containers. These results suggest that the insecticidal activities of the test compounds were attributable to contact mode of action, although there was also significant fumigant toxicity. The results indicate that the bioactive compound isolated from S. foetida could act as a potent insecticide against S. oryzae, C. chinensis, and T. castaneum populations.