극조생 온주밀감의 품질을 향상시키고자 宮本早生 10년생을 시험재료로 하고 과실비대기부터 성숙기까지 porous water proof sheet(PWPS), polyethylene film(PEF)을 부분 피복하여 토양온도, 산란광 및 품질의 변화를 조사하였다. PWPS 피복구는 PEF 피복구, 대조구에 비해서 고온하에서도 지온이 낮고 수관하부에서 측정된 광반사율이 높아 지온과 광환경이 개선되었는데 그 결과 수관하부에 착과된 과실의 착색이 촉진되었다.The study was carried out to elucidate the effects of partial mulch using porous water proof sheet on the fruit quality of very early-maturing satsuma mandarin (cv. Miyamotowase). The orchard was mulched with porous water proof sheet (PWPS) from the end of the rainy season to the fruit maturing. Non-mulching (control) and polyethylene film (PEF) mulching were also treated to compare with PWPS mulching. With PWPS mulching, soil temperature was decreased and the reflected light intensity was much higher than that of PEF mulching and control. These facts demonstrate the efficacy of mulching of PWPS to enhance peel coloration at the lower part of tree canopy.