Trees improve water storage and reduce soil evaporation in agroforestry systems on bench terraces in SW Uganda     

D. Siriri  J. Wilson  R. Coe  M. M. Tenywa  M. A. Bekunda  C. K. Ong  C. R. Black 《Agroforestry Systems》2013,87(1):45-58

The success of agroforestry in semi-arid areas depends on efficient use of available water and effective strategies to limit tree/crop competition and maximise productivity. On hillsides, planting improved tree fallows on the degraded upper section of bench terraces is a recommended practice to improve soil fertility while cropping continues on the lower terrace to maintain food production. This study examined the influence of tree fallows on soil water content (θ _w ) and evaporation (E _s ). Alnus acuminata Kunth (alnus), Calliandra calothyrsus Meissner (calliandra), Sesbania sesban L. (sesbania), a mixture of all three species, or sole crops (beans (Phaseolus vulgaris L.) or maize (Zea mays L.)) were grown on the upper terrace. The same sole crops were grown on the lower terrace. Four management regimes (unpruned, root, shoot and root + shoot pruned) were applied to the tree rows adjacent to the cropping area. Neutron probe and microlysimeter approaches were used to determine θ _w and E _s when the trees were c. 3.5 years old. Sesbania and alnus increased θ _w by 9–18 % in the cropping area on the lower terrace but calliandra reduced θ _w by 3–15 %. After heavy rain, E _s comprised 29–38 % of precipitation in the tree-based treatments and 53 % under sole crops. Absolute values declined as rainfall decreased, but E _s as a proportion of rainfall increased to 39–45 % in the tree-based treatments and 62 % for sole crops. Root + shoot pruning of alnus and the tree mixture increased θ _w in the cropping area but had no significant effect in the other tree-based treatments. The results suggest that sesbania and alnus can be planted on smallholdings without compromising water supply to adjacent crops, whereas calliandra decreased water availability despite reducing E _s . These results provide a mechanistic understanding of reported effects on crop yield in the same site.  相似文献   

Serum and urinary levels of salbutamol after chronic oral administration in a calf   总被引：2，自引：0，他引：2       下载免费PDF全文

Pou K  Adam A  Lamothe P  Gravel P  Messier J  Gravel A  Ong H 《The Canadian veterinary journal. La revue veterinaire canadienne》1992,33(7):467-468

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Tree growth and management in Ugandan agroforestry systems: effects of root pruning on tree growth and crop yield   总被引：1，自引：0，他引：1  

Wajja-Musukwe TN  Wilson J  Sprent JI  Ong CK  Deans JD  Okorio J 《Tree physiology》2008,28(2):233-242

Tree root pruning is a potential tool for managing belowground competition when trees and crops are grown together in agroforestry systems. We investigated the effects of tree root pruning on shoot growth and root distribution of Alnus acuminata (H.B. & K.), Casuarina equisetifolia L., Grevillea robusta A. Cunn. ex R. Br., Maesopsis eminii Engl. and Markhamia lutea (Benth.) K. Schum. and on yield of adjacent crops in sub-humid Uganda. The trees were 3 years old at the commencement of the study, and most species were competing strongly with crops. Tree roots were pruned 41 months after planting by cutting and back-filling a trench to a depth of 0.3 m, at a distance of 0.3 m from the trees, on one side of the tree row. The trench was reopened and roots recut at 50 and 62 months after planting. We assessed the effects on tree growth and root distribution over a 3 year period, and crop yield after the third root pruning at 62 months. Overall, root pruning had only a slight effect on aboveground tree growth: height growth was unaffected and diameter growth was reduced by only 4%. A substantial amount of root regrowth was observed by 11 months after pruning. Tree species varied in the number and distribution of roots, and C. equisetifolia and M. lutea had considerably more roots per unit of trunk volume than the other species, especially in the surface soil layers. Casuarina equisetifolia and M. eminii were the tree species most competitive with crops and G. robusta and M. lutea the least competitive. Crop yield data provided strong evidence of the redistribution of root activity following root pruning, with competition increasing on the unpruned side of tree rows. Thus, one-sided root pruning will be useful in only a few circumstances.  相似文献   

Agroforestry in Sustainable Agricultural Systems. L. E. Buck, J. P. Lassoie and E. C. M. Fernandes (Editors)     

Meka R. Rao  Chin K. Ong 《Agroforestry Systems》2000,49(1):103-106

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Glutenin Macropolymer in Salted and Alkaline Noodle Doughs     

Y. L. Ong  A. S. Ross  D. A. Engle 《Cereal Chemistry》2010,87(1):79-85

An attempt was made to understand the physicochemical attributes that are the basis of physical differences between alkaline and salted noodle doughs. Flour and dough properties of one soft and three hard‐grained wheat cultivars were observed. Doughs were made with either sodium chloride or sodium carbonate. Each formulation variant was tested at both high and low water additions. Samples for glutenin macropolymer (GMP) isolation were taken at selected noodle dough processing stages. When a 1.67% w/v Na₂CO₃ solution was used for mixograph testing, dough characteristics were radically altered and differences between cultivars were masked. In lubricated squeezing flow (LSF) testing, hard wheat noodle doughs had significantly (P < 0.01) longer relaxation times and higher % residual force values than soft wheat doughs in both the salted and alkaline variants. LSF maximum force and biaxial viscosity were significantly higher in alkaline doughs than salted. GMP extracted from alkaline doughs was gummy and sticky, and was more opaque than GMP from salted doughs. GMP weight decreased sequentially when extracted from samples taken in the active phase (mix, compound, sheet) of noodle dough processing and decreased more in alkaline doughs. GMP weight increased more after 24 hr of dough rest in salted doughs. GMP gel strength was noticeably higher in GMP extracted from alkaline doughs. After dough resting, alkaline GMP gel strength significantly increased, whereas it decreased in GMP from salted doughs, suggesting a role for GMP in the increased stiffness of alkaline noodle doughs.  相似文献   

Identification of a putative cellulase gene in the giant freshwater prawn,Macrobrachium rosenbergii (De Man, 1879)          下载免费PDF全文

Shen‐Shaun Ong  Subha Bhassu  Qi Bin Kwong  Peter Mather  Khanom Simarani  Rofina Yasmin Othman 《Aquaculture Research》2016,47(11):3653-3661

Nutrition plays an important role in the development of all organisms and in particular that of farmed aquatic species where costs associated with feed can often exceed 60% of total production costs. Crustacean species in addition, have the added metabolic requirement for regular moulting to allow normal growth and this requires large amounts of energy in the form of sugars (glucose). The current study explored the capacity of the giant freshwater prawn to produce endogenous cellulose‐degrading enzymes capable of extracting nutrients (simple sugars) from plant sources in formulated feeds used in the prawn aquaculture industry. We identified a putative cellulase cDNA fragment in the target organism of 1576 base pairs in length of non‐microbial origin that after protein modelling exhibited a TM‐score of 0.916 with a described cellulase reported from another crustacean species. The functional role of cellulase enzymes is to hydrolyse cellulose to glucose and the fragment identified in GFP was highly expressed in the hepatopancreas, the site of primary food digestion and absorption in crustaceans. Hepatopancreatic tissue from Macrobrachium rosenbergii also showed active digestion of cellulose to glucose following an endoglucanase assay. Cellulase gene(s) are present in the genomes of many invertebrate taxa and play an active role in the conversion of cellulose to available energy. Identification and characterization of endogenous cellulase gene(s) in giant freshwater prawn can assist development of the culture industry because the findings confirm that potentially greater levels of low‐cost plant‐material could be included in artificial formulated diets in the future without necessarily compromising individual growth performance. Ultimately, this development may contribute to more efficient, cost‐effective production systems for freshwater prawn culture stocks that meet the animal's basic nutritional requirements and that also support good individual growth rates.  相似文献   

Comparative Study of Photocatalytic Fuel Cell for Degradation of Methylene Blue under Sunlight and Ultra-Violet Light Irradiation     

Sin-Li Lee  Li-Ngee Ho  Soon-An Ong  Guat-Mei Lee  Yee-Shian Wong  Chun-Hong Voon  Wan Fadhilah Khalik  Nik Athirah Yusoff  Noradiba Nordin 《Water, air, and soil pollution》2016,227(12):445

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Why tree-crop interactions in agroforestry appear at odds with tree-grass interactions in tropical savannahs   总被引：4，自引：0，他引：4  

C. K. Ong  R. R. B. Leakey 《Agroforestry Systems》1999,45(1-3):109-129

This paper describes recent research findings on resource sharing between trees and crops in the semiarid tropics and attempts to reconcile this information with current knowledge of the interactions between savannah trees and understorey vegetation by examining agroforestry systems from the perspective of succession. In general, productivity of natural vegetation under savannah trees increases as rainfall decreases, while the opposite occurs in agroforestry. One explanation is that in the savannah, the beneficial effects of microclimatic improvements (e.g. lower temperatures and evaporation losses) are greater in more xeric environments. Mature savannah trees have a high proportion of woody above-ground structure compared to foliage, so that the amount of water 'saved' (largely by reduction in soil evaporation) is greater than water 'lost' through transpiration by trees. By contrast, in agroforestry practices such as alley cropping where tree density is high, any beneficial effects of the trees on microclimate are negated by reductions in soil moisture due to increasing interception losses and tree transpiration. While investment in woody structure can improve the water economy beneath agroforestry trees, it inevitably reduces the growth rate of the trees and thus increases the time required for improved understorey productivity. Therefore, agroforesters prefer trees with more direct and immediate benefits to farmers. The greatest opportunity for simultaneous agroforestry practices is therefore to fill niches within the landscape where resources are currently under-utilised by crops. In this way, agroforestry can mimic the large scale patch dynamics and successional progression of a natural ecosystem. This revised version was published online in June 2006 with corrections to the Cover Date.  相似文献   

First molecular detection of porcine bocavirus in Malaysia     

Daniel Mohan Jacob  Chee Yien Lee  Siti Suri Arshad  Gayathri Thevi Selvarajah  Faruku Bande  Bee Lee Ong  Peck Toung Ooi 《Tropical animal health and production》2018,50(4):733-739

Several strains of porcine bocaviruses have been reported worldwide since their first detection in Sweden in 2009. Subsequently, the virus has been reported to be associated with gastrointestinal and respiratory signs in weaner and grower pigs. Although Malaysia is host to a self-sufficient swine livestock industry, there is no study that describes porcine bocavirus in the country. This report is the first to describe porcine bocavirus (PBoV) in Malaysian swine herds. PBoV was identified in various tissues from sick and runt pigs using the conventional PCR method with primers targeting conserved regions encoding for the nonstructural protein (NS1) gene. Out of 103 samples tested from 17 pigs, 32 samples from 15 pigs were positive for porcine bocavirus. In addition, a higher detection rate was identified from mesenteric lymph nodes (52.9%), followed by tonsil (37.0%), and lungs (33.3%). Pairwise comparison and phylogenetic analyses based on a 658-bp fragment of NS1 gene revealed that the Malaysian PBoV strains are highly similar to PBoV3 isolated in Minnesota, USA. The presence of porcine bocavirus in Malaysia and their phylogenetic bond was marked for the first time by this study. Further studies will establish the molecular epidemiology of PBoV in Malaysia and clarify pathogenicity of the local isolates.  相似文献   

A strain-specific and a sex-associated STS marker for Asian arowana (Scleropages formosus, Osteoglossidae)   总被引：1，自引：0，他引：1  

G H Yue  D Ong  C C Wong  L C Lim  & L Orban 《Aquaculture Research》2003,34(11):951-957

A sex‐associated amplified fragment length polymorphism and a strain‐specific random amplified polymorphic DNA marker were identified from Asian arowana (dragonfish; Scleropages formosus Müller & Schlegel) by screening pooled genomic DNA samples from three different strains as well as males and females respectively. Both markers were cloned, sequenced and successfully converted into sequence‐tagged‐site (STS) markers. The strain‐specific STS marker could be applied to differentiate the Indonesian golden strain of Asian arowana from the green and blood‐red strains before the stage when colours become identifiable. Individuals from the green strain could be sexed with an efficiency of 82.7% using the sex‐associated STS marker. Thus, populations with preferred sex ratios can be formed without the need of rearing a large number of fish.  相似文献