不同氮源處理對萵苣硝酸氮含量日變化與鮮重的影響

Abstract

萵苣(Lactuca sativa L.) R36品種以3mM硝酸鈣(6mM N)或3mM硝酸銨(6mM N)處理，於8月12日下午8點開始採收，每隔3小時採收一次，採收至8月13日下午5點。3mM硝酸鈣與3硝酸銨兩種養液處理的地上部硝態氮含量皆有日變化，而且在8個採收時間，3mM硝酸鈣養液處理的地上部硝態含量皆高於3mM硝酸銨處理。8個採收時間的硝態氮含量平均，3mM硝酸鈣養液為乾物含量的0.68%，而3mM硝酸銨處理為0.29%。3mM硝酸銨養液處理的地上部與根部鮮重分別為3mM硝酸鈣處理的1.43倍及1.2倍。

Lettuce(Lactuca sativa L.) plants were hydroponically grown in solutions containing 3 mM Ca(NO3)2 or 3 mM NH4NO3 as nitrogen source. Mature plants were harvested eight times in one day at a 3 hr. interval from 8:00PM Aug. 12 to 5:00PM Aug. 13. Diurnal variations of the shoot nitrate content were observed in either Ca(NO3)2 or NH4NO3 treatment. Shoot nitrate content of Ca(NO3)2 treated plants were higher than those treated with NH4NO3 at every harvest. The average shoot nitrate content of lettuce with Ca(NO3)2 was 0.68% of the dry weight, and it was 0.29% for the NH4NO3 treated lettuce. The fresh weight of the NH4NO3 treated lettuce were 1.43 or 1.2 fold heavier than those with Ca(NO3)2 treatment for shoot or root respectively.