地面立柱式追日型光伏板下萵苣栽培評估

The Evaluation on Lettuce Cultivation under Mounted Solar-tracking Photovoltaic Panels

"本研究於立柱式追日型光伏板（photovoltaic panel, PVP）下，進行遮蔽率50%（PVP1）及25%（PVP2）處理，配合作物適栽期，評估結球及半結球萵苣生育表現並調查環境變化，以供營農型光電綠能農業設施下栽培作物之參考。結果顯示，單位面積產量與PVP遮蔽量呈現顯著負面效果，且不同種類萵苣在不同栽培季節間之變化量有所差異。除四月定植半結球‘桃源’萵苣產量較露天對照組增加21.7-26.7%外，其餘三期作試驗則呈現產量降低的趨勢，以50%遮蔽率PVP1處理之降幅較大，2-4、8-9及10-11月栽培之變化量分別為-14.4%、-50.1%及-28.1%，且品質方面降低，PVP下總可溶性固形物含量降低，硝酸鹽含量增加，葉球較鬆散，另植株淨光合作用速率及蒸散速率亦呈現較低的表現。分析PVP1下溫度較露天略低0.3oC-0.5oC，最大溫差達3.2oC，PVP2下則無顯著差異。四期作在PVP1下每日光積值之累積值（DLI）較露天分別降低28.4%、31.1%、23.9%及18.4%，PVP2減少量則分別為23.4%、13.5%、6.5%及10.8%。於半結球萵苣栽培期間，DLI累積值和產量成高度直線正相關（相關係數R2=0.64），可做為日後產量推估之參考。"

The aim of this study was to evaluate year-round cultivation of lettuce and environmental changes under single stand solar-tracking photovoltaic panels (PVP) with 50% (PVP1) and 25% (PVP2) coverage percentage. It was expected as a reference for crop cultivation under photovoltaic agricultural facilities. The results indicated that productive yield was significantly negative affected by PVP coverage and varied during cultivated cropping. Although semi-headed lettuce cultivated from April to May had 21.7%-26.7% yield increase compared with uncoverage treatment, the lower yields were observed in the rest three seasons especially under 50% coverage with -14.4%, -50.1%, and -28.1% changes from Feb. to April, Aug. to Sep., and Oct. to Dec., respectively. Considering quality, PVP treatment led to the decreasing total soluble solids content, raising nitrate content, and loosen head of lettuce. Net photosynthetic as well as transpiration rate also showed lower values than the opened field. Besides, air temperature under PVP1 was 0.3oC-0.5oC slightly lower than the open air and with maximum difference valued at 3.2oC, but there was no significant difference under PVP2. The accumulated daily light integral (DLI) during these fours experimental periods had 28.4%, 31.1%, 23.9%, and 18.4% reductions under PVP1, while 23.4%, 13.5%, 6.5%, and 10.8% decreases under PVP2. Highly linearly positive correlation (R2=0.64) existed between accumulated DLI and the yield of semi-headed lettuce. This study suggested that accumulated DLI could be used for its yield estimation.