植物工廠水耕量產芝麻菜之研究

芝麻菜有特殊的芝麻風味，作為搭配在生菜沙拉中食用有提味的效果，在台灣頗受多人喜愛。由於其單價高、生產期短、體積小、性喜冷涼，作為人工光型植物工廠內量產栽培是很好的選擇。本研究旨在建立以水耕方式在人工光型植物工廠量產芝麻菜之最適參數與產能最大化之最適栽培/採收模式。涉及之調整參數包括：溫度、光質、光量、光週期、日累積光量、栽培密度、養液配方、濃度、收穫日數等。首先探討發芽之最適溫度及光質，結果顯示在21°C、使用全紅光，第一日的發芽率即可略高於98%。其次，育苗階段應以廣域光譜的光源進行栽培。其三，探討單次早收 (第28天)、晚收 (第35天)與兩次採收 (第28, 35天) 搭配兩種栽培密度 (58、136株/m2)的栽培/採收模式，其單位面積全年產能 (kg/m2)由大至小依序為：單次晚收且低密度栽培、單次早收且高密度栽培、兩次採收且高密度栽培與單次早收且低密度栽培。第一種模式不僅單位面積全年產能最高，其光子產能 (Quantum Yield，單位g/mol) 也是最高。此四種模式的單位面積全年產能為文獻上提到田間栽培模式全年產能 (約6 kg/m2) 的2 ~ 6倍以上。對一間栽培床架達十層的植物工廠而言，其單位用地面積的全年產能可以是田間栽培的20~60倍以上。單次早收模式葉片硝酸鹽濃度稍高於4000 ppm，兩次採收模式在第二次採收前透過參數調控可得低於3100 ppm 的硝酸鹽濃度且不犧牲收成的鮮重。綜上所述，本研究推薦單次晚收且低密度的栽培/收穫模式應用於人工光型植物工廠內芝麻菜之量產。

關鍵字

植物工廠；芝麻菜；栽培法；水耕；硝酸鹽；光子產能

並列摘要

Rucola (Rocket salad in common, Eruca sativa）has sesame like flavor and is used as a flavor enhancement additive in a leafy green salad dish. It gets increasingly popular in Taiwan and is a potential crop for plant factory with artificial light only (PFwAL) due to its features such as: high price, fast grown, small in size, and originate from temperate climate region which can only be grown in late autumn and winter of Taiwan. The focus of this study is to investigate on suitable combinations of parameters for the production of hydoponic Rucola in PFwAL aiming at maximizing the annual yield per unit area and remain low in nitrate content. Parameters involves in the study include indoor air temperature, light quality, light intensity, duration of light period, daily light integral, planting density, types/concentrations of nutrient solution, and day of harvesting. Firstly, the results of seeding stage investigation appeal that the best temperature under the given condition is 21 degree C with red light as the light source. The germination rate can be higher than 98%. Secondly, artificial light with wide spectrum should be used in seedling stage. Thirdly, cultural practices, represented by planting density and day of harvest, were investigated. There are three types of cultural practices related to day of harvest, including early harvest (at day 28 after seeding), late harvest (at day 35 after seeding) and two time harvest (at day 28 and 35 after seeding) and two planting densities (58、136 plts/m2). The annual yield per unit area (in kg/m2) ranked from highest to lowest are as follows: Late harvest with low density > Early hrvest with high density > Two time harvest with high density > Early harvest with low density The cultural practice with highest yield also presents highest quantum yield (in g/mol). Compare with the annual yield in open field of approximately 6 kg/m2 described by the literature, annual yield of all cultural practices investigated in this study were 2 ~ 6 times higher. PFwAL have the capability of vertical production. For a 10 layers PF, the yield can be as high as 20 to 60 times compare with open field production. Cultural practice of early harvest will have nitrate content higher than 4000 ppm operated under current combination of parameters. Two time harvest with current practices can derive nitrate content lower than 3100 ppm without reducing fresh weight of Rucola. In conclusion, we recommend the ‘late harvest with low density model’ to be the cultural practice used in PFwAL.