Proposal of correction by LAI for evapotranspiration predicted by Penman method in potted miniature rose

In potted miniature rose production under recirculating Ebb and Flow system, the evapotranspiration was predicted from potential evapotranspiration, which was calculated by Penman Method, and total leaf area, which was predicted from meteorological factors. From the relation of evapotranspiration between observed and predicted by total leaf area, the evapotranspiration calculated from predicted total leaf area tended to be higher than that observed, and it was suggested that the evapotranspiration had to calculate from potential evapotranspiration and leaf area corrected by leaf area index (LAI). The evapotranspiration calculated from leaf area corrected LAI and potential evapotranspiration by Penman Method had close relation with the observed evapotranspiration, and a highly significant linear regression equation of Y=1.07X (Rsup(2) =0.75) was obtained between both evapotranspirations. And the evapotranspiration every 30 min might be predicted by air temperature, humidity and solar radiation. However, there was large difference between evapotranspiration observed and predicted in early growth stage within 10 days after hard pinch and latter growth stage with over 2.8 in LAI, the differences between evapotranspirations in these stages made precision of estimate equation for evapotranspiration decline. A close correlation was observed between soil water volume in pot and pF, and water content of pot soil at pF 2.1 was 93.0 ml/pot. The field capacity of the pot soil was fixed at 210.0 ml/pot regardless growth stages and cultivation periods of potted miniature rose, and the amount of available water for plant in a pot, which was equal to total evapotranspiration, was estimated at 117.0 ml/pot. Although it is within the growth range limited, the evapotranspiration in potted miniature rose production was predicted by air temperature, humidity and solar radiation from the results in this paper, and we might be able to predict watering time point in potted miniature rose production through weather data in greenhouse.