Influence of Grass Cover on Water Use and Shoot Growth of Young 'Fuji'/M.26 Apple Trees at Three Soil Water Regimes in Double Pot Lysimeters

토양수분영역을 달리한 double pot-lysimeter에서 자라는 '후지'/M.26 사과나무의 수분이용과 신초 생장에 미치는 잔디피복의 영향

This study measures the influence of grass cover on water use and shoot growth of apple trees growing under different soil water regimes in temperate climate conditions and evaluates monthly crop coefficients of such conditions during four months of the growing season in 1995. To do so, double pot lysimeter experiments of 3-year-old Fuji' apple (Males domestica Borkh.) trees under a transparent rain shield were designed and installed. Trees were triplicate under three soil water regimes: (A) drip-irrigation at -50 kPa of soil matric potential (IR50). (B) drip-irrigation at -80 kPa of soil matric potential (IR80), and (C) constant shallow water table at 0.45 m below the soil surface (WT45). In each treatment, two soil surface conditions were tested: the soil surface bare, and covered with turf grasses. Mean monthly water use increased with increasing soil matric potential for drip irrigation and was greatest in the WT45 treatment. Monthly crop coefficients increased linearly in time for drip-irrigated apple trees ($r^2$ values of $0.953^{***}$ for turf grass-covered system and of $0.862^{***}$ for bare surface system), while those obtained in the WT45 treatment fluctuated, Duncan's multiple range tests for shoot growth showed that grass-covered IR50 was most favorable to apple trees. while bare surface waterlogged situation was most adverse at least in part due to a lack of oxygen in the root zone. Mid-season leaf Kjeldahl-N was higher in drip-irrigated apple trees than in WT45 trees, while soil Kjeldahl-N was not different irrespective of treatments.

본 연구는 사과나무의 수분이용, 신초 생장 및 작물계수에 미치는 토양수분영역과 잔디 피복의 영향을 조사하였다. 이를 위해 비가림 시설하에 3년생 사과 '후지'/M. 26 (Malus domestica Borkh.)을 재식한 3반복 double pot-lysimeter 실험을 수행하였다: (A) 토양 매트릭 포텐셜 -50 kPa의 점적관수 (IR50), (B) 토양 매트릭 포텐셜 -80 kPa의 점적관수 (IR80), 및 (C) 지하 0.45 m의 정체 자유수면 (WT45), 각 처리에 나지와 잔디 피복의 두 가지 지표상태를 두었다. 평균 월별 수분이용은 IR50 처리에서 IR80 처리보다 컸으며, WT45 처리에서 가장 컸다. 점적관수 처리 사과나무의 월별 작물계수는 시간의 1차 함수로 증가하였으나 ($r^2=0.953^{***}$, 잔디 피복 $r^2=0.862^{***}$, 나지), WT45 처리 사과나무의 작물계수는 변동하였다. 신초생장은 잔디 피복 IR50 처리에서 가장 컸으며, 나지 WT45 처리에서 가장 작았다. 토양의 Kjeldahl 질소는 처리에 관계없이 동일하였으나 8월 10일 측정한 엽중 Kjeldahl 질소는 WT45 처리보다 점적관수 처리에서 높았다.