Optimizing nitrogen use efficiency in wheat and potatoes: interactions between genotypes and agronomic practices

One approach to decrease the environmental impact of crop production and reduce costs is to optimize agronomic practices and genotypes so that nutrients are used more efficiently. In this study the effects of agronomic practices (rotations, crop protection, fertilization) on yields, nitrogen use efficiency (NUE) and associated parameters were studied in an experiment using two winter wheat genotypes (Cordiale and Scaro) in one season and two potato genotypes (Sarpo Mira and Sante) in two seasons. The wheat showed no varietal differences in yield and NUE; instead the fertilization regime was the main factor affecting yield and NUE with higher values observed when conventional fertilization was used. The exception was for wheat grown after three years grass/clover ley when there was no added yield benefit from conventional fertilization of the organically bred variety (Scaro). This demonstrates the potential for N fixing crops to provide sufficient N to high yielding cereals if grown for long enough prior to planting. The greatest gains in NUE were achieved by combining an N efficient genotype with conventional crop management in an organic rotation. Fertilization and genotypic variation were the main factors affecting potato tuber yield and NUE, with the late maturing Sarpo Mira displaying elevated yields and NUE compared with the early maturing Sante. The use of organic fertility sources resulted in lower NUE, but N release from organic sources may increase NUE of future crops. This highlights the need for long-term nutrient balance and modelling studies to assess NUE at the crop rotation scale.     

Sizing and performance features of rotary and reciprocating positive displacement pumps

An overview of some popular rotary and reciprocating positive displacement (PD)pump types is given with the objective of presenting and comparing the respective sizing relationships and performance fea...     

Diazinon Accumulation and Dissipation in Oryza sativa L. Following Simulated Agricultural Runoff Amendment in Flooded Rice Paddies

Flooded post-harvest rice paddies were examined as systems for reducing diazinon (organophosphate insecticide) concentrations in stormwater runoff. Two paddies were cultivated in Oryza sativa L. and amended with a 3-h simulated stormwater diazinon runoff event. Initial diazinon adsorption peaked at 347 and 571 μg kg^?1 (3% mass load reduction) for mean above-ground plant tissue concentrations in each pond, respectively. Subsequent senescence of above-ground tissue showed significant decreases in tissue mass (r ²?=?0.985) and adsorbed diazinon mass (90?±?4% and 82?±?1%) within 1 month of amendment. There were no corollary increases in water column diazinon concentrations. Furthermore, control O. sativa tissue placed within the treatment ponds had below-detectable levels of diazinon throughout the decomposition phase, suggesting a lack of within pond transference of dissipated diazinon. This study shows the relative effectiveness of diazinon adsorption by post-harvest rice plants and a potential mitigation strategy of senescence and pesticide degradation for contaminated tailwater.     

Wild ostrich (<Emphasis Type="Italic">Struthio camelus australis</Emphasis>) reproduction in Orbata,a nature reserve in Tunisia

The aim of the current investigation was to determine wild ostrich reproductive behaviour in Orbata Nature Reserve by observing 16 hens and 28 cocks over a seven-year period. Intense laying commenced in January, one month after the cessation of the rainy season, and 92% of the eggs were produced during the dry season (January to May, peaking in March). Over the seven years, 1,322 eggs were laid in 69 nests, which corresponded to an annual average production of 19.2 ± 9.1 eggs/nest and 11.8 eggs/hen. 24 nests (34.78%) were non-brooded, 17 nests (24.64%) were deserted in the course of incubation, and 28 nests (40.58%) possessed hatched eggs. All the non-incubated nests had egg losses equivalent to 46.6 ± 12.6%. Hatchability success of incubated eggs was 41.9 ± 12.0%. Ostriches tended to dig their nests adjacent to the reserve enclosure which had direct access by road and track, the latter subjecting them to human disturbance and predation. The systematic obstruction of these nests stimulated ostriches to build additional nests within the reserve perimeter. The authors discussed the results recorded in an ostrich flock in relation to the environmental factors (climatic factors, food disponibility and predation) and suggested possibilities for improved wildlife management.     

Effect of Progesterone and Ionomycin on Domestic Cat Sperm Motility Patterns and Acrosome Reaction

This study was aimed at assessing the changes in sperm motion patterns and the percentage of acrosome reaction (AR) in domestic cat semen after treatment with either ionomycin or progesterone (P₄). Ten ejaculates were collected from five tomcats using an artificial vagina, and were diluted, centrifuged and resuspended in a capacitation medium. Samples were evaluated and divided into seven equal aliquots and, after 2 h at 25°C, were incubated for 30 min at 38°C in 5% CO₂ and then analyzed. Computer-assisted sperm analysis and a combination of three fluorescent probes were used to assess sperm plasma, acrosomal membrane integrity and mitochondrial transmembrane potential. Thirty minutes after the start of incubation, P₄ was added (10 μg/ml) to the P1 group. Groups P2 and P3 were supplemented with P₄ (10 and 20 μg/ml, respectively) only after 2 h of incubation, and groups I1 and I2 were supplemented with ionomycin (4 and 8 μ m , respectively) 2 h after incubation. Group E was supplemented with ethanol (0.6%) at 2 h after incubation and group C received no supplementation. Ionomycin and P₄ treatments led to a hyperactivation-like sperm motion and an increase (p < 0.05) in the percentage of AR. Although a higher (p < 0.05) percentage of AR was obtained in group I2 when compared with all P₄ groups, a decrease (p < 0.05) in total and progressive motility was observed in I2 group. As I1 group was similar to I2 to induce AR without diminishing sperm motility, we can conclude that ionomycin at 4 μ m seems to be more suitable to trigger AR in domestic cat sperm.     

The wild ostrich (<Emphasis Type="Italic">Struthio camelus</Emphasis>): a review

The aim of the current report was to study the literature pertinent to wild populations of ostriches and their ecological and behavioural adaptations in the wild. Selected areas included palaeontology; ostrich distribution; conservation status and relationships with humans and habitat. There is an immediate and urgent need to conserve and protect the apparently rapidly declining populations of wild ostriches with the committed involvement of governments and funding bodies. Wildlife management is an important complement to the farming of livestock. Scientists need to understand the elements of ostrich behaviour in the wild in order to make informed decisions on their management and contact with other animals. Information of the like should be included in readily-accessible and annually updated wildlife manuals. We deemed that such information was an essential part in the conservation of this dwindling ratite.     

Resource-use,body condition and parasite load metrics indicate contrasting health of stocked and native game fishes in Canadian prairie lakes

This study evaluated the status of native and stocked fish species in 13 prairie lakes in central Canada over eight years (2007–14) using three metrics: resource-use (benthic versus pelagic carbon via stable isotopes); body condition (relative weight index W_r); and parasite load (cestode gut enumerations). Analyses included game and non-game fishes, like naturally occurring northern pike, Esox lucius L., and yellow perch, Perca flavescens Mitchill, but focused on stocked walleye, Sander vitreus (Mitchill) because it supports a robust recreational fishery. Walleye and northern pike were significantly more reliant on benthic carbon than yellow perch or forage fishes (p < 0.05), but this reliance was not associated with any measured environmental variables for any species. In lakes with game fishes, forage fishes exhibited higher reliance on benthic energy, possibly due to predator avoidance strategy, particularly yellow perch. Walleye body condition index was consistently lower (<95–105) than values exhibited by the other two game fishes (81–139), and parasites were only common in walleye and associated with lake-water salinity (r² = 0.93, p < 0.05) and sex (p < 0.05). Based on the results, the most desirable game fish, walleye, appears less resilient to environmental variability than northern pike and yellow perch, making this species more susceptible to impacts of future climate change.