• Korean Journal of Agricultural Science
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• v.16 no.2
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• pp.169-178
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• 1989

The study was carried out to elucidate the feedback mechanism on the hypothalamo-hypophyseal system from the functional changes of ovary in female rats. One hundred and forty-four mature female rats were lloted into the three groups; ovariectoimzed group, estradiol treated group and intact control group. The varies of 48 heads of rat were completely removed. Forty eight heads of rat were administered with $200{\mu}g$ of estradiol benzoate every 48 hours. Serum FSH, LH and prolactin levels were determined with radioimmunoassay method at 3,6,12,24 ours, and 5,10, and 15days after treatment. The rats were necropsied to measure the weights of hypophysis and to examin the histological changes in the organs. The results obtained were as follows: The weights of hypophysis were increased after ovariectomy and decreased after estradiol injection. The differences in hypophysis weights were significant between the group from 5 days after treatment. The histological changes in hypophysis were appeared from 5th day after ovariectomy. Proliferation and hypertrophy began to occur in basophilic from 10th day after ovariectomy, chromophobes were slightly hypertrophied and acidophilic cells were atrophied. In estradiol injected rats the histological findings were appeard to be contrary to those of ovariectomized rats. Serum FSH levels significantly changed after ovariectomy and estradiol injection and were higher in both the treated groups than in the intact control group. Within 18 hours after treatment the level was the highest in ovariectomized group, and thereafter the highest level was found in estradiol treated gorup. In ovariectomized rats the levels were rapidly increased 3 hours after treatment and maximum levels were found 18 hours after treatment. In estradiol treated rats the levels started to increase 18 hours after treatment and reached maximum levels 24 hours treatment. 4. Serum LH levels started to increase 3 hours after ovariectomy and estradiol injection and reached maximum levels 12 hours after ovariectomy and 24 hours after estradiol injection. There were significant differences in LH levels between the groups in each observation time. Up to 18 hours after treatment levels were higher in ovariectomized rats than in estradiol treated rats. but thereafter the levels were higher in estradiol treated rats than in ovariectomized rats. The multiple range test showed that a significant difference in LH levels was not found between ovariectomized group and estradiol treated group 18 hours and 5 days after treatment. 5. Serum prolactin levels were significantly changed after ovariectomy and estradiol injection. The levels were lower in ovariectomized rats than in intact control rats.

• Korean Journal of Soil Science and Fertilizer
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• v.10 no.3
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• pp.103-134
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• 1977

The physiological and biochemical role of potassium for upland crops according to recent research reports and the nutritional status of potassium in Korea were reviewed. Since physical and chemical characteristics of potassium ion are different from those of sodium, potassium can not completely be replaced by sodium and replacement must be limited to minimum possible functional area. Specific roles of potassium seem to keep fine structure of biological membranes such as thylacoid membrane of chloroplast in the most efficient form and to be allosteric effector and conformation controller of various enzymes principally in carbohydrate and protein metabolism. Potassium is essential to improve the efficiency of phoro- and oxidative- phosphorylation and involve deeply in all energy required metabolisms especially synthesis of organic matter and their translocation. Potassium has many important, physiological functions such as maintenance of osmotic pressure and optimum hydration of cell colloids, consequently uptake and translocation of water resulting in higher water use efficiency and of better subcellular environment for various physiological and biochemical activities. Potassium affects uptake and translocation of mineral nutrients and quality of products. potassium itself in products may become a quality criteria due to potassium essentiality for human beings. Potassium uptake is greatly decreased by low temperature and controlled by unknown feed back mechanism of potassium in plants. Thus the luxury absorption should be reconsidered. Total potassium content of upland soil in Korea is about 3% but the exchangeable one is about 0.3 me/100g soil. All upland crops require much potassium probably due to freezing and cold weather and also due to wet damage and drought caused by uneven rainfall pattern. In barley, potassium should be high at just before freezing and just after thawing and move into grain from heading for higher yield. Use efficiency of potassium was 27% for barley and 58% in old uplands, 46% in newly opened hilly lands for soybean. Soybean plant showed potassium deficiency symptom in various fields especially in newly opened hilly lands. Potassium criteria for normal growth appear 2% $K_2O$ and 1.0 K/(Ca+Mg) (content ratio) at flower bud initiation stage for soybean. Potassium requirement in plant was high in carrot, egg plant, chinese cabbage, red pepper, raddish and tomato. Potassium content in leaves was significantly correlated with yield in chinese cabbage. Sweet potato. greatly absorbed potassium subsequently affected potassium nutrition of the following crop. In the case of potassium deficiency, root showed the greatest difference in potassium content from that of normal indicating that deficiency damages root first. Potatoes and corn showed much higher potassium content in comparison with calcium and magnesium. Forage crops from ranges showed relatively high potassium content which was significantly and positively correlated with nitrogen, phosphorus and calcium content. Percentage of orchards (apple, pear, peach, grape, and orange) insufficient in potassium ranged from 16 to 25. The leaves and soils from the good apple and pear orchards showed higher potassium content than those from the poor ones. Critical ratio of $K_2O/(CaO+MgO)$ in mulberry leaves to escape from winter death of branch tip was 0.95. In the multiple croping system, exchangeable potassium in soils after one crop was affected by the previous crops and potassium uptake seemed to be related with soil organic matter providing soil moisture and aeration. Thus, the long term and quantitative investigation of various forms of potassium including total one are needed in relation to soil, weather and croping system. Potassium uptake and efficiency may be increased by topdressing, deep placement, slow-releasing or granular fertilizer application with the consideration of rainfall pattern. In all researches for nutritional explanation including potassium of crop yield reasonable and practicable nutritional indices will most easily be obtained through multifactor analysis.

• Korean Journal of Agricultural Science
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• v.10 no.2
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• pp.221-234
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• 1983

A study was conducted to devise a method to estimate the edible meat weight in live broilers. White Cornish broiler chicks CC, Single Comb White Leghorn egg strain chicks LL, and two reciprocal cross breeds of these two parent stocks (CL and LC) were employed A total of 240 birds, 60 birds from each breed, were reared and sacrificed at 0, 2, 4, 6, 8 and 10 weeks of ages in order to measure various body parameters. Results obtained from this study were summarized as follows. 1) The average body weight of CC and LL were 1,820g and 668g, respectively, at 8 weeks of age. The feed to gain ratios for CC and LL were 2.24 and 3.28, respectively. 2) The weight percentages of edible meat to body weight were 34.7, 36.8 and 37.5% at 6, 8 and 10 weeks of ages, respectively, for CC. The values for LL were 30.7, 30.5 and 32.3%, respectively, The CL and LC were intermediate in this respect. No significant differences were found among four breeds employed. 3) The CC showed significantly smaller weight percentages than did the other breeds in neck, feather, and inedible viscera. In comparison, the LL showed the smaller weight percentages of leg and abdominal fat to body weight than did the others. No significant difference was found among breeds in terms of the weight percentages of blood to body weight. With regard to edible meat, the CC showed significantly heavier breast and drumstick, and the edible viscera was significantly heavier in LL. There was no consistent trend in neck, wing and back weights. 4) The CC showed significantly larger measurements body shape components than did the other breeds at all time. Moreover, significant difference was found in body shape measurements between CL and LC at 10 weeks of age. 5) All of the measurements of body shape components except breast angle were highly correlated with edible meat weight. Therefore, it appeared to be possible to estimate the edible meat wight of live chickens by the use of these values. 6) The optimum regression equations for the estimation of edible meat weight by body shape measurements at 10 weeks of age were as follows. $$Y_{cc}=-1,475.581 +5.054X_{26}+3.080X_{24}+3.772X_{25}+14.321X_{35}+1.922X_{27}(R^2=0.88)$$ $$Y_{LL}=-347.407+4.549X_{33}+3.003X_{31}(R^2=0.89)$$ $$Y_{CL}=-1,616.793+4.430X_{24}+8.566X_{32}(R^2=0.73)$$ $$Y_{LC}=-603.938+2.142X_{24}+3.039X_{27}+3.289X_{33}(R^2=0.96)$$ Where $X_{24}$=chest girth, $X_{25}$=breast width, $X_{26}$=breast length, $X_{27}$=keel length, $X_{31}$=drumstick girth, $X_{32}$=tibotarsus length, $X_{33}$=shank length, and $X_{35}$=shank diameter. 7) The breed and age factors caused considerable variations in assessing the edible meat weight in live chicken. It seems however that the edible meat weight in live chicken can be estimated fairly accurately with optimum regression equations derived from various body shape measurements.