值物工廠內波士頓萵苣立體化栽培模式之探討

Abstract

本研究旨在探討於密閉環控室內栽培波士頓萵苣的各項環境控制與設備操作參數，讓波士頓萵苣的栽培能夠不受外在環境影響而達全年穩態量產之目的，除此之外，本研究建立的系統，單位面積產能更必須超越前人之研究成果。密閉環控室以保溫隔熱材料為外壁，配備人工光源、空調設備、立體化栽培層架、養液循環與環境監控系統，後者允許室內日夜溫、濕度、光量、二氧化碳濃度與養液循環時間與頻度的監控。 比較六種不同光質的人工光源，萵苣於育苗階段以紅藍 (紅：90%，藍：10%)的光質照射下可得最佳之鮮重。採收前改變養液濃度的做法可以有效降低萵苣硝酸鹽濃度，但會大幅影響鮮重，此方面需要後續實驗來找出更好的辦法。 波士頓萵苣於自製栽培層架上經過35天栽培 (育苗14天、育成21天)後，每一育成栽培架 (四層) 可收獲60株，每株平均鮮重可達155 g。環控室內面積7.83 m2可容納五座育成栽培架和一座育苗栽培架，每週可收穫兩個育成栽培架。若將此環控室放大7倍，則每天可以收穫120株平均重量155 g的萵苣，單位面積產能120 kg/m2/year，遠高於康乃爾大學以溫室單層栽培之68 kg/m2/year，也高於本研究室學長的 95 kg/m2/year。本研究室前後兩系統的主要差別在於本研究將育成階段再分成兩階段，栽培密度稍有不同，前期較之前的密，光能使用較為經濟，後期較之前的疏，最終產物的單株重量因此大幅提高。 本研究證實在環控室內以人工光源取代陽光，搭配水耕系統種植萵苣不僅能夠維持植物的正常生理，植物能維持旺盛成長，且可以完全杜絕農藥之使用。在未包含人工成本、廠房和設備之折舊下，環控室一天之操作成本為260元，換算後成本為9.78元/100 g，以日本植物工廠栽培之水耕萵苣售價200日圓/100 g相比(折合台幣80元/100 g)，台灣與日本的消費者對於安全、無農藥但價位稍高的蔬菜的接受度均頗高，這全球化的趨勢已是非常明顯，植物工廠在全球，特別是台灣與日本都有著很大的發展潛力。

This study is to research into diverse operating conditions inside a closed system where all the environmental factors are controlled to cultivate Boston lettuce (Lactuca sativa) in multi-layer stands. Tubular fluorescent light is substituted for sunlight to obtain a more stable light condition. Air conditioning system, homemade benches, re-circulating nutrition system, monitoring and control system, artificial lighting system and carbon dioxide supplement system are mounted in the controlled chamber. In this study, Boston lettuce provided with red-blue (red: 90%, blue：10%) light gets the heaviest fresh weight in seedling stage. To adjust nutrient solution concentration before harvesting can decrease the nitrate concentration of lettuce effectively. It takes 35 days to grow Boston lettuce, including seedling stage for 14 days and cultivating stage for the rest 21 days. Totally 60 heads of lettuce can be harvested from one cultivating shelf (4 layers) with the average fresh weight of 155 g/head. The inner area of the controlled room is 7.83 m2 which can accommodate 1 seedling shelf and 5 cultivating shelves. 120 heads of Boston lettuce can be harvested every week from this system. If the controlled room is enlarged 7 times, 120 heads can be harvested every day. Conversion into annual production per square meter of this system is 120 kg which is far higher than 68 kg got by Cornell’s hydroponic greenhouse. The cultivation density decreases when lettuce grows bigger, so the light source can be utilized more efficient in early stage and the final fresh weight per head can grow heavier with lower density. This study shows that we can not only maintain the regular physiology of Boston lettuce with artificial light but also avoid using any pesticide. According to cost analysis, the production cost of Boston lettuce is 9.78 NTD/100 g, without considering labor cost and depreciation of structure and equipment. Based on the results of this research, plant factory is a profitable and potential industry.