본 시험은 유기농 사과과원에서 생육초기인 5월과 6월에 ‘후지’ 사과나무 주위를 청결상태로 유지했을 때 잎과 토양의 무기성분 및 수체생장과 수확량에 미치는 영향을 조사하였다. 조기예초구 (5월과 6월에 예초)는 관행예초구(6월말 한번 예초)보다 높은 예초량 발생으로 수체에 높은 무기성분을 공급하였지만 토양과 잎의 칼륨함량을 증가시킨 것 이외에는 다른 무기성분에는 별다른 영향이 없었다. 하지만 엽내 칼륨은 관행재배에서 보고한 기준치보다 낮은 농도를 나타내었다. 두 처리 모두 재배 중기까지 토양에 약 200 g 전후의 전질소를 공급하여서 8년생 사과나무가 요구로 하는 질소량을 충족시켰다. 조기예초구는 수체의 수관증가와 원면적을 증가시킴으로써 과실의 수량을 관행예초구 보다 증가시켰다.

Reductions in the ozone column have led to substantial increase in UV-B radiation at the Earth's surface with the amount and intensity dependent on atmospheric and geographic factors. Our objectives were to understand the effect of UV-B radiation on photosynthesis and carbohydrate synthesis of soybean, and to establish an indicator to select resistant soybean cultivar against UV-B radiation. Soybean seeds (cv. Daepungkong) were sown and grown for 4 weeks in an environmentally controlled chamber. UV-B radiation was delivered to plants for four hours, each day, from 10:00 to 14:00 h by five fluorescent UV lamps. A distance of 1 m from lamps to the top of plants was always maintained throughout the experiment. The biologically effective UV-B radiation level was 21.6 kJ m-2 d-1 using the generalized plant responses action spectrum normalized at 300 nm. The damage of soybean leaves was optically observed at the second day of UV-B radiation, and leaf veins were first injured. Photosynthetic rate was reduced after 2 days of UV-B radiation, and, at 5 days, it was a half level (6.3 μmol m-2 s-1) compared with control (12.1 μmol m-2 s-1). UV-B radiation led to the reduction of stomatal conductance around 5 days of treatment. The decrease in stomatal conductance means the reduction of leaf transpiration and the influx of carbon dioxide. Also, the reduction of photosynthetic rate caused an accumulation of the intercellular carbon dioxide. It is suggested that photosynthetic characteristics can be used an indicator to select UV-B-resistant soybean cultivar.