Estimating evapotranspiration in semi-arid rangelands: connecting reference to actual evapotranspiration and the role of soil evaporation     

Onalenna Gwate  Sukhmani K Mantel  Andiswa Finca  Lesley A Gibson  Zahn Munch  Anthony R Palmer 《African Journal of Range and Forage Science》2019,36(1):17-25

In a context of water scarcity, efforts to increase landscape production should focus on improving water productivity. This requires an appreciation of the various components of evapotranspiration (ET), including soil evaporation (E_s) because the latter reflects ‘unproductive’ water loss. Both complex and simple algorithms have been developed to determine ET. In data scarce areas, developing and testing parsimonious algorithms is useful. This study sought to improve a simple single layer ET model by incorporating an E_s component. Empirical methods were also explored to predict ET from vegetation indices (VIs), leaf area index (LAI) and reference evapotranspiration (ET₀). A large aperture scintillometer and an eddy covariance (EC) system were used to validate the proposed algorithm at three sites over Grasslands and Albany Thicket biomes in the Eastern Cape, South Africa. There was good agreement between the observed and predicted ET with RMSE of 0.30–0.58 mm d^?1 when average daily observed ET was 0.43–3.24 mm. The VIs had moderate correlations with the observed data due to the significant role played by E_s (65%–84%) across the sites and stomatal conductance at the Albany Thicket site. The simple algorithms developed would make determining ET easier in data scarce regions.  相似文献   

Anti‐Müllerian hormone is expressed and secreted by bovine oviductal and endometrial epithelial cells     

Raihana Nasrin Ferdousy  Onalenna Kereilwe  Hiroya Kadokawa 《Animal Science Journal》2020,91(1)

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Heifers express G‐protein coupled receptor 153 in anterior pituitary gonadotrophs in stage‐dependent manner          下载免费PDF全文

Kiran Pandey  Onalenna Kereilwe  Hiroya Kadokawa 《Animal Science Journal》2018,89(1):60-71

We recently found that orphan G‐protein‐coupled receptor (GPR)153 is expressed in the anterior pituitary (AP) of heifers, leading us to speculate that GPR153 colocalizes with gonadotropin‐releasing hormone receptor (GnRHR) in the plasma membrane of gonadotrophs and is expressed at specific times of the reproductive cycle. To test this hypothesis, we examined the coexpression of GnRHR, GPR153, and either luteinizing hormone or follicle‐stimulating hormone in AP tissue and cultured AP cells by immunofluorescence microscopy. GPR153 was detected in the gonadotrophs, and was colocalized with GnRHR in the plasma membrane. GPR153 was also detected in the cytoplasm of cultured gonadotrophs. Real‐time PCR and western blot analyses found that expression was lower (P < 0.05) in AP tissues during early luteal phase as compared to pre‐ovulation or late luteal phases. The 5′‐flanking region of the GPR153 gene contained a consensus response element sequence for estrogen, but not for progesterone. These data suggest that some, but not all GPR153 colocalizes with GnRHR in the plasma membrane of gonadotrophs, and its expression changes stage‐dependently in the bovine AP.  相似文献   

Exploring the invasion of rangelands by Acacia mearnsii (black wattle): biophysical characteristics and management implications     

Onalenna Gwate  Sukhmani K Mantel  Andiswa Finca  Lesley A Gibson  Zahn Munch  Anthony R Palmer 《African Journal of Range and Forage Science》2016,33(4):265-273

Australian acacias have spread to many parts of the world. In South Africa, species such as A. mearnsii and dealbata are invasive. Consequently, more effort has focused on their clearing. In a context of increasing clearing costs, it is crucial to develop innovative ways of managing invasions. Our aim was to understand the biophysical properties of A. mearnsii in grasslands as they relate to grass production and to explore management implications. Aboveground biomass (AGB) of A. mearnsii was determined using a published allometric equation in invaded grasslands of the northern Eastern Cape, South Africa. The relationships among the A. mearnsii leaf area index (LAI), normalised difference vegetation index (NDVI) and AGB were investigated. The influence of A. mearnsii LAI and terrain slope on grass cover was also investigated. Strong linear relationships between NDVI, LAI and AGB were developed. Acacia mearnsii canopy adversely impacted grass production more than terrain slope (p < 0.05) and when LAI approached 2.1, grass cover dropped to below 10% in infested areas. Reducing A. mearnsii canopy could promote grass production while encouraging carbon sequestration. Given the high AGB and clearing costs, it may be prudent to adopt the ‘novel ecosystems’ approach in managing infested landscapes.  相似文献