Please use this identifier to cite or link to this item:
Studies on the economical management of nutrient solution of hydroponic head lettuce
結球萵苣學名 Lactuca sativa L. var. capitata L. 為菊科萵苣屬植物，主要以生食為主，為現代農業具高經濟價值的作物，因以生食為主需注意生菌數，因此有些採用水耕方式栽培。影響作物水耕栽培成敗的因子除環境因子外：光照、氣溫、溼度、病蟲害等；養液的配方和供應方式：pH、電導度值（EC）、水溫、養分的組成等亦相當重要。養液的經濟管理不僅考慮作物生長條件，亦考慮如何降低成本。本論文用一系列試驗探討結球萵苣的配方，及其養液供應方式。
(1)探討氮、鎂、鈉之影響：試驗處理以鎂為處理變級，及有無添加鈉以及銨態氮的影響。試驗結果顯示鎂的處理對產量影響統計上不顯著，且於最高濃度55 mg/kg處理有下降趨勢；添加鈉顯著提高產量。而銨態氮處理因養液之pH太低且未調整產量顯著較低。(2) 適植高溫期作物採用小白菜探討養液容器中空氣空間比率影響及白天與晚上養液供應對小白菜的效應，並以白天或晚上只供應養液為管理方式，針對白天不供應養液方面與添加再移動性弱的Ca和Fe養分比較。試驗結果，養液以 air / tank = 3/5 的處理最佳，而白天和晚上皆需要供應養液。若白天不供應主要養液則需添加再移動力弱之養分，如Ca與Fe。(3) 探討結球萵苣的耐鹽性：採用不更換養液方式栽培，以不同養液濃度（1/2倍、1倍、3倍、5倍養液濃度），探討結球萵苣忍受高養液濃度能力，另有一處理為降低養液高度（air / tank = 3/5）。結果顯示，降低養液高度能獲得較高產量，因1 倍、3 倍、5 倍養液濃度處理間產量差異不顯著，故結球萵苣能忍受5倍養液濃度，EC值約5 mS cm-1。(4) 探討分次添加養液及以FeSO4取代EDTA-Fe 效應：試驗結果，分次添加養液的效果不顯著，全部氮肥皆採用硝酸態氮處理產量無顯著差異，鐵以FeSO4或EDTA-Fe兩者產量無明顯差異。(5)探討依前面試驗結果養液配方依K/N 2.6、P/N 0.21、Ca/N 0.31以及Mg/N 0.08，其中氮的用量為150 mg/L 並驗證分次添加養液效應。結果發現分次添加養液並無顯著差異。
水耕栽培結球萵苣，採用靜置式， FeSO4 取代 EDTA-Fe ，及一次供應足量養分等管理方式以降低成本，達高經濟目的。各種養分皆提高，氮為 150 mg L-1，磷為 31 mg L-1，鉀為 389 mg L-1，鈣為 46.6 mg L-1，鎂為 12 mg L-1，養液的 pH 為 6.4 ~ 6.2，電導度值為 1.4 ~ 1.2 mS cm-1。
The head lettuce (Lactuca sativa L. var. capitata L.) has been a high commercial agricultural product. It is mainly consumed as table salad thus its Aerobic Plate Counts is highly concerned and some farms growing with hydroponic technology. Environmental factors (light, temperature, humidity, and plant disease) and formulae of nutrient (pH, EC, water temperature, and elemental composition) affect the success of hydroponic culture. This thesis carried out a series of experiments to find an economical management in nutrient solution.
There were five experiments conducted. In experiment 1, the effect of concentrations of nitrogen, magnesium, and sodium in nutrient solution on the growth of head lettuce was studied. The results showed that the increase of concentration of Mg in nutrient solution increased the concentration of Mg in plant tissue but did not increase the yield of head lettuce, even significantly decreased its yield as Mg concentration reached 55 mg L-1. The addition of sodium significantly increased the yield of head lettuce, but the addition of ammonium nitrogen decreased its yield significantly due to low solution pH. In experiment 2, the effect of air/solution ratio of solution container and the supply of nutrient solution in day or night on Pak-chio growth were studied. Using Pak-chio instead of head lettuce because it is too hot for growing head lettuce during summer time in Taiwan. Results showed that the increase of air space increased the yield of Pak-chio for better root growth. The yield of Pak-chio was significantly decreased as deioned water was used instead of nutrient solution either during night or day times. The addition of Fe and Ca during the day improved the yield for treatment supplied nutrient solution during the night. 3. In experiment 3, four strengths (1/2, 1, 3, and 5 times) of nutrient solution without renewing were carried out to study tolerance of head lettuce on EC. The result showed that only the yield of treatment of half strength nutrient solution is significant lower, there were no significant difference among other treatments. This indicated that the head lettuce could tolerate high concentration of nutrient solution with EC reached 5 mS cm-1. In experiment 4, the effect of equal total amount of nutrients added to nutrient solution by splitting with 1, 2, or 3 times and forms of FeSO4-Fe and EDTA-Fe were studied. Results showed that there are no significant differences of yields of head lettuce among treatments. This indicated that the all nutrients can be added at the beginning once without splitting, and FeSO4 can be used instead of EDTA-Fe. In experiment 5, a solution formula with K/N 2.6, P/N 0.21, Ca/N 0.31, Mg/N 0.08, derived by previous results, with the concentration of nitrogen based at 150 mg L-1 and added by 1, 2 and 3 times. The result showed that there are no significant differences among treatments.
The head lettuce can grow successfully by static hydroponic system with air space at 60% of container volume, all nutrients added at the beginning with splinting and using FeSO4-Fe instead of EDTA-Fe on reducing the total cost in economical consideration. The composition of main nutrients can be set at N, 150 mg L-1; P, 31 mg L-1; K, 389 mg L-1; Ca, 46.6 mg L-1; Mg, 12 mg L-1; pH, 6.2 to 6.4.
|Appears in Collections:||土壤環境科學系|
Show full item record
TAIR Related Article
Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.