氮肥及氣象環境對設施葉萵苣生長及硝酸鹽含量之影響

Effects of Nitrogen Fertilization and Climatic Environment on Growth and Nitrate Content of Lettuce (Lactuca sativa) Grown under Protected Structure

蕭巧玲(Chiao-Ling Hsiao) ； 楊純明(Chewn-Ming Yang) ； 何佳勳(Chia-Hsun Ho) ； 蔡淑珍(Shwu-Jene Tsai) ； 林毓雯(Yu-Wen Lin) ； 劉滄棽(Tsang-Sen Liu)

《作物、環境與生物資訊》 10卷4期 (2013/12) Pp. 284-289

https://doi.org/10.30061/CEB.201312_10(4).0006

摘要

葉菜類蔬菜硝酸鹽累積過量的問題時有所聞，栽植期間的管理及環境條件被認為係影響硝酸鹽含量變化的主要因素之一。本研究以‘明豐3號’ （'Ming Feng No. 3'）圓葉萵苣（Lactuca sativa）為參試葉菜作物，利用簡易設施於2012年5月至10月期間在行政院農業委員會農業試驗所農場進行試驗，以探討4種氮肥處理及栽培期間氣象環境差異對於葉萵苣生長及硝酸鹽含量的影響。試驗結果顯示，不同施肥組合的氮含量由低至高時，株高、葉片數及鮮重等生長性狀亦呈現增加趨勢，類似於硝酸鹽含量的上升現象。進一步分別分析鮮重與乾重、硝酸鹽之間的關係，可發現增施氮肥將同時帶動硝酸鹽與鮮重的升高，並增進實質乾物質（乾重）的累加。反之，減少氮肥用量雖可降低硝酸鹽含量，卻也造成較小株形葉萵苣。又發現栽植期間的氣象環境亦影響硝酸鹽累積及植株生長，由採收前一日之日射量及日均溫與硝酸鹽的關係，顯示在較低日射量及日均溫下，葉萵苣植體內的硝酸鹽含量較高。若經於採收當天日出前進行藍光照射處理，在氣溫28℃以下時將可降低植體硝酸鹽含量13.1－17.3%。由此推知，氮肥施用量的增加，將有利於葉萵苣硝酸鹽的形成及生質量累加而促進植株生長，清晨採收前施予光照則具有減少硝酸鹽含量的效果。

關鍵字

硝酸鹽 ； 葉萵苣 ； 設施栽培 ； 氣象環境 ； 光照

並列摘要

Excessive nitrogen accumulation in leafy vegetables may be caused by mismanagement and inappropriate climatic conditions during growing period and hence, brings up food safety concerns in public. To clarify effects of nitrogen fertilization and climatic environment on growth and nitrate content of leafy vegetable, lettuce (Lactuca sativa), variety 'Ming Feng No. 3', was applied with four different doses of nitrogen fertilizer and grown under protected structure in the experimental farm of Taiwan Agricultural Research Institute from May to October in 2012. Results showed that plant height, leaf number and plant fresh weight were increased with the increasing amounts of nitrogen fertilizer application, similar to the rising trend of nitrate content. From the relationship between plant fresh weight and nitrate content, it indicated that applying higher quantity of nitrogen fertilizer would improve both nitrate content and plant fresh weight, which was in conform with the increase of plant dry matter (dry weight). In contrast, lower nitrogen application would result in a low nitrate content and smaller plant size and weight. By comparing the relationships between daily irradiance and daily mean air temperature and nitrate content one day before harvest, nitrate content was found higher in conditions of lower irradiance and temperature. By lighting before dawn with blue LED (light-emitting diode) prior to harvest and under 28℃, nitrate content was reduced by 13.1-17.3% relative to those plants without lighting treatment. Accordingly, application of nitrogen fertilizer will in favor of nitrate assimilation and dry matter formation to enhance plant growth. Lighting before dawn prior to harvest is one way to cut down nitrate content in tissues of leafy vegetable.

並列關鍵字

Nitrate ； Lettuce (Lactuca sativa) ； Cultivation under protected structure ； Climatic environment ； Lighting