Showing papers in "Kasetsart Journal. Natural Sciences in 2013"

Effects of drought and tapping for latex production on water relations of Hevea brasiliensis trees

Abstract: The impact of drought conditions on the water relations of rubber trees is important because the trees could shed leaves while they are being continuously tapped. The aim of this work was to study the effect of soil drought and the tapping of latex on the water relations of rubber trees. This study distinguished between untapped trees and trees affected by tapping activity. The experiment was conducted on 14-15 year-old rubber trees from the clone, RRIM 600, at the Chachoengsao Rubber Research Center (CRRC). Climatic measurement, soil water content, predawn and midday leaf water potential, stand transpiration and percentage loss of hydraulic conductivity (PLC) were measured from January 2009 to January 2010, especially in the dry season. Under drought conditions, during the rainy season, stand transpiration and predawn leaf water potential decreased in response to soil drought in August. The midday leaf water potential and PLC did not change following soil water stress. In the dry season, the plant water status was related to climatic variables and soil drought. The results indicated that drought induces a reduction in the plant water status of rubber trees. Tapping activity did not have a marked infl uence on the water balance of the rubber trees. However, tapping reduced the sap fl ux density and stomatal conductance; thus, attention must be paid to tapping in the dry season, particularly in dry areas. (Resume d'auteur)

Correlation and path analysis of palm oil yield components in oil palm (Elaeis guineensis Jacq.).

Abstract: Thisresearchaimedtoevaluatethecorrelationcoefficients,�directeffectsandindirecteffects� of agronomic characters on palm oil yield components for selection and improvement of next-generation oil palm populations. The seven crosses of oil palms aged 4 yr were investigated at three locations in southern Thailand. The experiment at each location was designed as a completely randomized design withfivereplications.�Dataonbunchyield,�yieldcomponentsandbunchcomponentswerecollected� fromJuly�2009�toJune�2010.�Combinedanalysiswasusedtoestimatethevarianceandcovariancefor� thecalculationofcorrelationcoefficientandpathcoefficientvalues.�Theresultsshowedthatthebunch� yield,�singleweight,�freshmesocarpperfruitandfruitperbunchhadpositivegenotypicandphenotypic� correlationcoefficientvalueswithregardtopalmoilyield�(1.03,�0.93,�1.70,�0.13�and�0.85,�0.56,�0.32,� 0.34,�respectively).�Thepathanalysisindicatedthatthebunchyield,�freshmesocarpperfruitandfruit� perbunchhadapositivedirecteffectonboththegenotypeandphenotypeofpalmoilyield�(1.32,�0.68,� 0.27�and�0.94,�0.20,�0.31,�respectively).�Although,�thesingleweighthadapositivecorrelationcoefficient� valueforbothgenotypeandphenotype,�ithadanegativedirectgenotypicandphenotypiceffectonpalm� oilyield.�Therefore,�palmoilyieldimprovementshouldbeconsideredespeciallyintermsofthebunch� yield,�freshmesocarpperfruitandfruitperbunch,�becausethesecharactershadhigh,�positivedirect�

Seasonal Abundance of Blow Flies (Diptera: Calliphoridae) in Three Urban Parks of Bangkok, Thailand

Abstract: Designing effective management programs for insect vectors of human and livestock diseases requires knowledge of the species composition and seasonal abundance of the vectors. The seasonality of blow fl ies was assessed throughout 1 yr with baited traps in three tropical, urban parks in Bangkok, Thailand. A total of 11,625 blow fl ies were captured and identifi ed, consisting of fi ve species from three genera—Chrysomya megacephala (Fabricius) (73.37%), C. rufi facies (Macquart) (22.96%), Hemipyrellia ligurriens (Wiedemann) (3.27%), C. nigripes Aubertin (0.38%) and Phumosia indica (Surcouf) (0.03%). More females were collected than males with a ratio of 2.9:1, respectively. Abundance of the two most common species showed a trimodal pattern with peaks in January, September and June and the three most common species occurred in baited fl y traps throughout the year. The greatest number of C. megacephala was captured in January while C. rufi facies peaked in September. Hemipyrellia ligurriens was more abundant during June to October. Abundance levels of the two most common species were negatively correlated with the temperature and relative humidity.

Diurnal dynamics of stand transpiration and stomatal conductance in rubber (Hevea brasiliensis Muell. Arg.)

Abstract: Transpiration at the leaf and stand level is mainly controlled by climatic conditions. The diurnal dynamics of stand transpiration and stomatal conductance were analyzed in rubber trees. The experiment was conducted using 13 yr-old rubber trees from clone RRIM 600 under natural conditions at the Chachoengsao Rubber Research Center during January to December 2007, with sampling in the dry season, the rainy season and early in the dry season. At the stand level, the stand transpiration was monitored using sap fl ow measurement and estimated evapotranspiration from meteorological data. At the leaf level, the stomatal conductance was measured using a portable photosynthesis system on the leaves exposed to the sun. The leaf water potential was measured using a pressure chamber and the soil water content was measured by the gravimetric method. Climatic measurements were recorded using a weather station above the canopy. The plant water status was correlated with the climatic conditions and soil water content. The diurnal dynamics of stand transpiration and stomatal conductance were mainly controlled by the vapor pressure defi cit and net radiation. The stomatal conductance was more sensitive to climatic variations than stand transpiration. There were different time lags between the stomatal conductance and stand transpiration throughout the year. The relationship between the climatic factors and transpiration varied throughout the year. (Resume d'auteur)

Salmonella Prevalence in Slaughtered Buffaloes and Cattle in Champasak Province, Lao People's Democratic Republic

Abstract: This is the fi rst local study of Salmonella prevalence in slaughtered buffaloes and cattle in Champasak province, Lao PDR. In total, 269 animals (225 buffaloes and 44 cattle) were examined for the presence of Salmonella in mesenteric lymph nodes, caecum, abdominal and diaphragmatic muscles. The proportion of slaughtered buffaloes and cattle identifi ed as positive for Salmonella was 6.69%, with 7.11% in buffaloes and 4.54% in cattle. The highest proportion was identifi ed in the Houayset (9.67%), followed by the Nasaykham (6.25%) abattoir, and the lowest proportion was found in the KhanGneng abattoir (5.37%). No Salmonella was found in the Houayphek abattoir. Only 3.25% (22 of 676) of all samples collected were identifi ed as contaminated with Salmonella. Out of 22 isolates, four serotypes and three untypable Salmonella-attributed to serogroups B, C and E, were identifi ed. S. Weltevreden accounted for 45.45% (10 of 22) of the total isolates, followed by S. Brunei 22.72% (5 of 22) and S. 8,20:-:13.63% (3 of 22), while a similar level of 4.54% was found for S. Typhimurium, S. Bovismorbifi cans, S. 4.5.12:b:- and S. 8,20:y:- . The results indicated that slaughtered buffaloes and cattle sampled in this study served as sources of Salmonella in humans. Hence, slaughterhouse surveillance of Salmonella and other food-borne diseases is needed in order to prevent Salmonella from reaching foodstuffs meant for human consumption.

Effect of fermented by-product and rice straw on milk yield and fatty acid composition in dairy cows.

Abstract: This experiment used by-products from agro-industry waste as a roughage source for dairy cows. Bagasse, pineapple peel, corn cob, corn stover and vinasse were used to produce fermented byproduct (FBP). The objective of this study was to determine the effects of FBP with rice straw on the milk yield, milk composition and fatty acid profile in dairy cows. Fifteen dairy cows with 75–87.5% Holstein Friesian blood were used with an average initial body weight (± SD) of 407.33 ± 53.48 kg in mid-lactation and 111.25 ± 25.12 days in milk. Cows were randomly allocated to three treatments (T1 = five dairy cows fed rice straw ad libitum; T2 = five dairy cows fed FBP with rice straw at the ratio 50:50 (dry basis) ad libitum; T3 = five dairy cows fed sweet corn waste silage with rice straw at the ratio 50:50 (dry basis) ad libitum) using a completely randomized design. Data were adjusted with parity and initial body weight as covariates. The results revealed that the milk yield and 4% fat-corrected milk from cows fed FBP with rice straw were found to be the highest (P < 0.05) among all treatments. The caproic acid (C6:0) and palmitoleic acid levels (C16:1) from cows fed FBP with rice straw were the highest (P < 0.05) among all treatments. Moreover, short chain fatty acids (SCFAs), long chain fatty acids (LCFAs) and polyunsaturated fatty acids composed of γ-linolenic (C18:3n6c), α-linolenic (C18:3n3c), eicosatrienoic acid (C20:3n6) and arachidonic acid (C20:4n6) were significantly highest in cows fed FBP with rice straw. The body weight change and average daily gain obtained from cows fed with FBP and rice straw were found to be the highest among all treatments. It was concluded that dairy cows fed FBP with rice straw at the ratio of 50:50 on a dry matter basis increased the milk yield and the SCFA and LCFA contents. The present study showed great benefit from feeding FBP and rice straw as a ready-to-feed practice producing higher milk yield and quality.

Foraging effects of the invasive alien fish Pterygoplichthys on eggs and first-feeding fry of the native Clarias macrocephalus in Thailand.

Abstract: Native to Latin America, the sailfi n armored catfi sh Pterygoplichthys has been introduced to Thailand for the ornamental fi sh industry. This invasive species has fl ourished in nature and may threaten aquatic resources, especially of indigenous freshwater fi sh due to its foraging activities. This study investigated the biological impacts of the sailfi n armored catfi sh on the eggs and the fi rst-feeding fry of the Thai native catfi sh, Clarias macrocephalus that are found in similar habitats. The results showed that small, medium and large Pterygoplichthys fed on up to 95% or more of native catfi sh eggs within 24 hr. Pterygoplichthys also consumed the fi rst-feeding fry of C. macrocephalus. The average consumption of fifry by small, medium and large Pterygoplichthys was 26.3±7.2, 71.8±23.5 and 86.3±13.7%, respectively. These results clearly indicated that the consumption of the catfi sh eggs was much higher than for the fi rst-feeding fry primarily due to the fact that the eggs were immobile and accessible. In addition, the consumption rates of fi rst-feeding fry by the armored catfi sh were positively correlated with the size of Pterygoplichthys (correlation coeffi cient = 0.6238, P < 0.01). In conclusion, Pterygoplichthys can destroy the eggs and fi rst-feeding fry of the native catfi sh Clarias macrocephalus and has the potential to reduce the populations of Thai native fi sh species.

Occurrence of tetraploidy in colchicine-treated physic nut (Jatropha curcas Linn.).

Abstract: A study on the effect of colchicine on the physic nut (Jatropha curcas Linn.) was carried out at a research site in Pathum Thani province. Colchicine was used to treat plants of physic nuts of clones FF25B-14 and FF20SBr-3 at 500–8,000 ppm for 10 d. The results showed that colchicine concentrations at 5,000–6,000 ppm affected the size of vegetative and reproductive parts such as the leaves, infl orescence and staminate fl owers compared with normal plants. The treated plants showed larger stomatal size than nontreated plants. Study of the chromosome number revealed that the treated plants had doubled chromosomes (44) compared to the normal plants. These plants were assumed to be 4n or tetraploids while the normal plants were 2n or diploids (2n = 22). Both the vegetative growth and yield of the tetraploid plants were lower than in normal plants.