氯施與量對於溫州蜜柑（Citrus unshiu）營養狀況之影響以及不同根砧對吸收氯之感受性

Nutritional Effect of Chloride on Citrus unshiu and the Susceptibility to Chloride Uptake on Different Rootstocks

本省部份柑桔園所植溫州蜜柑有嚴重落葉現象，初疑與所施大量氯化鉀肥料中之氯有關，經調查分析，比較蒙害及未蒙害柑桔園土壤，顯示氯含量與10.3-63.3 ppm間，應不為高，且各園土壤質地，以及較高之有機物含量，均有利於氯之稀釋、湔洩，加之比較健株與蒙害植株間土壤條件之無顯著差別，則此種嚴重落葉現象應非為氯所導至。另以210、1050及2100ppm氯培育以枳殼、酸桔、粗檸檬及美女桔等四種根砧接合之溫州密柑，比較研究不同根砧對氯之感受性，其結果展示氯吸收量隨施用量而增，而不同根砧於高濃度處理下，對氯之感受性呈顯著差異性。經16週之培育觀察2100及1050 ppm氯處理，枳殼砧、酸桔砧以至粗檸檬砧之組合，於培育至8週或14週時，葉片先後變黃、脫落、而終枯死，或僅止於嚴重落葉，而同一試驗中之美女桔砧組合則仍健存。如參照葉片含氯百分率，作為氯傷害情形之研判，則如長期處於高濃度氯之介質中，葉片含氯遠小於0.4%時，亦將罹害。

Defoliation was seriously ocourred in Citrus unshiu at some groves in Taiwan which was suspected to be related to chloride accumulation in the substratum due to heavy application of KCl fertilizer. In the investigation of soil samples taken from groves had occurred the defoliation cases and the unaffected grove, it appeared that chloride was not high (10.3-63.3 ppm) while the sandy loam soil as well as the higher organic matters in the soil will be very helpful to chloride dilution and leaching. In addition to the indistinctive characteristics of soil samples between affected and unaffected plants it can be judged that the defoliation cases may be irrelevant with chloride. In the study of susceptibility to chloride uptake on different rootstocka, C. unshiu was grafted on Poncirus trifoliata, C. sunlit, C. jambhiri and C. reshni rootstocks and grew in nutrient solutions containing 210, 1050 and 2100 ppm chloride respectively. The results revealed that chloride absorption enhanced following the increment of its concentration and the susceptibility is variant significantly between rootstocks under high concentration treatments. In a period of 16 weeks observation, injury occurred on about 8 or 14 weeks In the plants grafted, on P. trifoliata, C. sunki and C. jambhiri under the 2100 and 1050 ppm chloride treatments. Leaves became yellow, serious defoliation and the plants died thereafter (2100 ppm treatment). But in all cases, plants on C. reshni stock were unharmed. To make reference to % chloride in leaf blades in judging the injured condition, it can be expressed that when growing in the medium high in chloride for a long period then even its content farther lesser 0.4% in the leaves, plants shall suffer harm.