Nutrient use efficiency and harvest index of cassava decline as fertigation solution concentration increases

Response of cassava (Manihot esculenta Crantz) to fertigation as a form of nutrient delivery is unknown. The objectives of this study were to establish a balanced nutrition and to enhance agronomic nutrient use efficiency (ANUE) of cassava under fertigation. This study was conducted in the greenhouse and in the field. In both, the results showed a similar trend. There were six fertigation concentrations and three cassava varieties, selected for their duration of growth in the field. Shoot biomass of the long‐duration variety (Nalumino) was the highest, even though its dry root yield was the lowest (10.18 t ha^?1) among the varieties. In contrast, the medium‐duration variety (Kampolombo) produced the highest dry root yield (20.34 t ha^?1) and a lower shoot biomass. The highest root yield of the shortest‐duration variety (Mweru) was achieved at 200 mg N, 30 mg P, and 200 mg K L^?1 (155.0, 23.3, 155.0 kg N, P, K ha^?1), while Nalumino's was at 70 mg N, 7 mg P, and 70 mg K L^?1 (54.3, 5.4, 54.3 kg N, P, K ha^?1). ANUE and harvest index of these varieties declined as the fertigation concentrations increased. Additionally, the correlation between concentrations of N in the youngest fully expanded leaf (YFEL) blades and dry root yields was the lowest (R² = 0.5488), whereas P and K were R² = 0.7237 and R² = 0.8006, respectively, an indication that nutrient concentrations in the leaf, especially N, cannot easily be used to predict root yield. When cassava reaches nutrient sufficiency, mainly N, its accumulation in the leaf continues without significant increase in the root yield.     

Effects of resistant starch type III polymorphs on human colon microbiota and short chain fatty acids in human gut models

This study probed the possible effects of type III resistant starch (RS) crystalline polymorphism on RS fermentability by human gut microbiota and the short chain fatty acids production in vitro. Human fecal pH-controlled batch cultures showed RS induces an ecological shift in the colonic microbiota with polymorph B inducing Bifidobacterium spp. and polymorph A inducing Atopobium spp. Interestingly, polymorph B also induced higher butyrate production to levels of 0.79 mM. In addition, human gut simulation demonstrated that polymorph B promotes the growth of bifidobacteria in the proximal part of the colon and double their relative proportion in the microbiota in the distal colon. These findings suggest that RS polymorph B may promote large bowel health. While the findings are limited by study constraints, they do raise the possibility of using different thermal processing to delineate differences in the prebiotic capabilities of RS, especially its butryrogenicity in the human colon.     

Effect of soil moisture on the release of alachlor from alginate-based controlled-release formulations

The release of alachlor from controlled-release formulations (CRFs) based on alginate-montmorillonite matrices into aqueous polyethylene glycol (PEG) solutions of different concentrations and into a soil at different moisture contents was studied. In distilled water and in PEG-containing solutions displaying -0.1 MPa potential and up, the beads imbibe water and swell. The ensuing increase in weight is about 5%, and the increase in the bead's diameter is about 10%. At water potentials of -0.5 MPa and lower, loss of weight and shrinkage of the beads were observed. The changes in weight and diameter of the alginate-clay beads incubated in a Hamra loamy sand soil at 26.5% moisture content (w/w; -0.18 MPa) were similar to those observed in PEG solutions of >-0.5 MPa moisture potential. The weight and diameter losses observed in the drier soils (12.0 and 7.1% water content; -0.49 and -1.11 MPa) were similar to those in the more concentrated PEG solutions. A decrease in the rate of release of the active ingredient from the beads into soil was observed as the water potential decreased (drier soils). The release of the active ingredient from the investigated CRFs displayed a linear relationship to the square root of time, suggesting a diffusion-controlled-release rate. Data extracted from this relationship enabled the formulation of a mathematical model that correlates rate of release to water content.     

A COMPLETE MOBILE RADIOLOGY LABORATORY FOR LARGE ANIMAL FIELD WORK

Because of the lack of a large animal hospital in Israel, and the need to provide radiology service to equine and bovine patients, a complete radiology mobile laboratory for field work was built. The laboratory was constructed in a van-type automobile and is equipped with a condenser-discharge x-ray unit, a tabletop automatic processor, and a dark room facility. The qualities of each of the components and the operation of the laboratory are discussed.     

Dog bite wounds in dogs and cats: a retrospective study of 196 cases

The age, type, etc., time of injury, body areas injured, treatment modalities and mortality rates were reviewed in 185 dogs and 11 cats that were bitten by dogs. Male dogs were more frequently bitten than females, and small dogs (< or = 10 kg) were not only the most common victims but also were more likely to suffer multiple injuries. Mortality occurred only in cases with thoracic or abdominal injuries. Exploratory thoracotomy, performed in some of the cases presented with penetrating thoracic injury, did not prove to alter prognosis. Cats are not as frequently bitten as dogs, and are often younger than the mean age of cats in the overall hospital population.     

Trends in the use of conservation tillage in US agriculture

Abstract. In 1996 conservation tillage was used on nearly 36% of the cropped area of the USA. This level has remained relatively unchanged over the past few years. The use of conservation tillage varied by crop and was dependent on site-specific factors including soil type, topsoil depth, and local climatic conditions. A number of economic, demographic, geographic, and policy factors have affected the adoption of conservation tillage. While it was not possible to quantify exactly the impact of these factors, it was clear that management complexities and profitability are key factors impeding an increase.     

Tree age effect on fine-root and leaf morphology in a silver birch forest chronosequence

The influence of forest ageing on fine-root morphology and relations between fine-root and leaf characteristics is poorly studied. The aim of this study was to analyse age-driven changes in ectomycorrhizal roots (EcM roots) and leaf morphology in a chronosequence of silver birch (Betula pendula Roth.), which would provide a better understanding of adaptation responses and acclimation capacity of tree roots and leaves. The chronosequence included six age classes (3, 6, 14, 32, 45, and 60 years.). All stands had regenerated naturally and grew in a highly productive Oxalis forest site type in Estonia. Most changes in the morphology of EcM roots and leaves of silver birch occur faster at a young age. The functional parameters—mean specific area of EcM root (SRA) and leaf specific area (SLA) as well as leaf N—decreased with age. EcM root SRA and specific root length (SRL) decreased with stand age as a result of increased mean diameter and tissue density. In age classes of 6, 14, and 32 years, the total number of dominating EcM taxa was 34, and the distribution of four different dominating EcM exploration types (contact-, short-, medium-, long-distance) was similar. We conclude that high values of SRA, SLA, and leaf N measured in young silver birch stands indicate high activity of physiological processes necessary for fast-growing young trees. A decrease of SLA and SRA and N in the chronosequence of fertile stands of silver birch is most probably caused by down-regulation of growth, affecting simultaneously leaves and fine roots.