Critical nitrogen content and nitrogen nutrition index for sweetpotato crop

Abstract

Sweetpotato is an important tuber crop for the food security in Island countries of the South Pacific. The allometric relationship between tissue nitrogen (N) concentration and aerial dry matter is unknown. We determined critical N (N_c) content from vegetative stage to harvesting, and estimated the range of variation in N nutrition index (NNI) from two field experiments with varied rates of N (0, 25, 60, 125 and 180?kg N ha^?1 in 2015 and 0, 50, 125, 175 and 250?kg N ha^?1 in 2017). A unified critical N curve (N_c = 3.338?W^?0.307) where W?=?aerial dry matter with W?≥?1.38 t ha^?1, was constructed based on the N concentration in the aerial dry matter. The calculated NNI ranged from 0.69 to 1.23 in 2015 and 0.54 to 1.17 in 2017. The preliminary N_c dilution curve and NNI determined could potentially be used as a parameter for N management.     

Aspects of the reproductive biology of the southern mullet,Liza richardsoni,from Algoa Bay,South Africa

The reproductive biology of the southern mullet from Algoa Bay was studied between June 1978 and October 1980. Gonadosomatic indices and macroscopic and microscopic examinations of the gonads were used to establish the breeding cycle. The period of greatest sexual development extends from September to March and spawning occurred throughout that period. Spawning probably occurs close in shore. Liza richardsoni exhibited the phenomenon of group synchronism, two distinct oocyte groups being present within a pre-spawning ovary. The proportion of yolkless oocytes exceeded that of vitellogenic oocytes in ripe fish. However, it was not apparent whether all the vitellogenic oocytes would reach maturity. This highlights the need for quantitative histological studies to accompany fecundity estimates. Histological investigations were useful in the clarification of breeding cycle determinations based on gonadosomatic indices and visual macroscopic assessments.     

Marine Benthic Diatoms Contain Compounds Able to Induce Leukemia Cell Death and Modulate Blood Platelet Activity

In spite of the high abundance and species diversity of diatoms, only a few bioactive compounds from them have been described. The present study reveals a high number of mammalian cell death inducing substances in biofilm-associated diatoms sampled from the intertidal zone. Extracts from the genera Melosira, Amphora, Phaeodactylum and Nitzschia were all found to induce leukemia cell death, with either classical apoptotic or autophagic features. Several extracts also contained inhibitors of thrombin-induced blood platelet activation. Some of this activity was caused by a high content of adenosine in the diatoms, ranging from 0.07 to 0.31 μg/mg dry weight. However, most of the bioactivity was adenosine deaminase-resistant. An adenosine deaminase-resistant active fraction from one of the extracts was partially purified and shown to induce apoptosis with a distinct phenotype. The results show that benthic diatoms typically found in the intertidal zone may represent a richer source of interesting bioactive compounds than hitherto recognized.     

Phenolic content as an indicator of tolerance of cowpea seedlings to <Emphasis Type="Italic">Sclerotium rolfsii</Emphasis>

The role of phenolics in plant tolerance to pathogen infection is well documented. The objective of the present preliminary investigation was to study phenolic metabolites involved in the tolerance or susceptibility of cowpea (Vigna unguiculata Walp.) cultivars to Sclerotium rolfsii Sacc. and to use their presence as a possible screening tool. Total, free acid, ester-bound and cell wall-bound phenolics of 10 cowpea cultivars were quantified. In healthy seedlings, the tolerant cultivars displayed the higher phenol content than the susceptible cultivars. In S. rolfsii infected seedlings, the highest increase was found from 48 h after inoculation. The net effect of inoculation was a 630% increase in total phenolics (soluble and insoluble) in the stem of tolerant cultivars while the total phenolic content increased only by 212% in the stems of susceptible cultivars. Although, no significant difference (P = 0.05) was detected among cultivars, in terms of free acid phenolics, the amount of ester-bound and cell wall-bound phenolics significantly increased, therefore demonstrating a similar trend to the one observed for the total phenolic content. These preliminary results showed that the presence of phenolics before and after S. rolfsii infection may be used as a rapid screening method for detection of tolerance to S. rolfsii damping-off and stem rot of cowpea.     

Tree species composition,biodiversity and regeneration in response to catena shape and position in a mountain forest

We examined the variation in woody plant species composition, regeneration and biodiversity in relation to topographic heterogeneity, specifically catena shape (V and Λ) and slope position (summit, shoulder, back slope, foot slope and toe slope). All research took place at the TMU Experimental Forest Station, located in northern Iran. Two sets of replicated quadrats were established along transects that encompassed the different catena shapes and positions. We recorded the density, height, and canopy cover of all trees ≥12 cm diameter at breast height within 30 quadrats (400m²), as well as the density of all tree regenerations within 120 quadrats (4m²). In addition, three measurements of biodiversity were calculated for both mature trees and regenerations. Mature tree species composition varied greatly with catena shape and slope position, as did that of regenerating trees. Despite differences in species composition, the various measurements of biodiversity were consistent across the landscape for mature trees, whereas significant variation in evenness was detected for regenerating trees. We concluded that the broad matrix of environmental conditions occurring within this rugged mountainous area generates a variety of microhabitats, which in turn contributes to both the variation in species composition and the consistent biodiversity of these forests.     

Linking future population food requirements for health with local production in Waterloo Region,Canada

Regional planning for improved agricultural capacity to supply produce, legumes, and whole grains has the potential to improve population health as well as the local food economy. This case study of Waterloo Region (WR), Canada, had two objectives. First, we estimate the quantity of locally grown vegetables, fruits, legumes, and whole grains needed to help meet the Region of Waterloo population’s optimal nutritional requirements currently and in 2026. Secondly, we estimate how much of these healthy food requirements for the WR population could realistically be produced through local agriculture by the year 2026. Results show that a shift of approximately 10% of currently cropped hectares to the production of key nutritious foods would be both agriculturally feasible and nutritionally significant to the growing population. We supplement our findings with some agronomic considerations and community-level strategies that would inform and support such change. The methodology of this study could be applied to other regions: more such analyses would create a broader picture of the diverse qualitative and quantitative agricultural shifts that could synchronize optimal land use with dietary recommendations, thus informing coordinated policy and planning.     

Accuracy and suitability of selected sampling methods within conifer dominated riparian zones

Sixteen sampling alternatives were examined for their performance to quantify selected attributes of overstory conifers in riparian areas of western Oregon. Each alternative was examined at eight headwater forest locations based on a 0.52 ha square stem maps. The alternatives were evaluated for selected stand attributes (trees per hectare, basal area per hectare and height to diameter ratio), using root mean square error, absolute percent bias, and mean absolute deviation as criteria. In general, rectangular strip designs outperformed fixed area circular or radial plots and variable area plots. Sampling 3.6 m wide strips perpendicular to the stream outperformed all other alternatives.     

Prevalence and patterns of self-reported animal-related injury among veterinarians in metropolitan Kampala

To establish the prevalence, patterns and risk factors of animal-related injuries among veterinarians, self-administered questionnaires were given to 60 veterinarians practicing in metropolitan Kampala. The prevalence of animal-related injuries in metropolitan Kampala was 72% (95%CI, 57~84). Some veterinarians (34%) suffered multiple injuries with a mean and median of 2.1 and 2.0 injuries per veterinarian, respectively. Of a total of 70 self-reported animal related injuries, cattle accounted for 72%, cats for 25%, dogs for 23%, self inoculation for 15% and birds for 13%. Injuries associated with poultry did not require hospital treatment. The upper limb was the most the frequently (68%) injured anatomical body part of veterinarians, and vaccination of animals (25%) was the major activity associated with injury. Animal-related injuries are common among practicing veterinarians in metropolitan Kampala; however, they did not differ significantly based on the veterinarian''s gender, experience or risk awareness.     

Extramural Ectopic Ureter in a Domestic Ferret (Mustela putorius furo)

Ectopic ureter is the most common cause of congenital urinary incontinence in the dog and cat. The occurrence of ectopic ureter in the dog has been estimated to be 0.016%. A 6-month-old ferret was evaluated for urinary incontinence and urine scalding around the perineal and inguinal areas. Ultrasonography showed a nondistended urinary bladder that contained a possible intraluminal blood clot. Excretory urography revealed a left ectopic ureter. The ferret was initially treated with oral amoxicillin-clavulanate and topical silver sulfadiazine ointment for the perineal and inguinal dermatitis associated with the incontinence. Because of the potential for complications and additional surgery with ureteral transplantation, a left nephroureterectomy was performed. Surgical recovery was uneventful and the incontinence improved, although a small amount of incontinence-associated dermatitis was still present 24 days after discharge. Phenylpropanolamine therapy was initiated to address a suspected dysfunction of the urethral sphincter. Urinary incontinence improved with the phenylpropanolamine therapy; however, a small amount of incontinence persisted throughout the 3 months in which the ferret was evaluated. To the authors' knowledge, this is the first report of an ectopic ureter in a domestic ferret.