栽培密度及遮陰對小白菜（Brassica campetstris L. Chinensis group）生長及硝酸根離子含量之影響

小白菜為短期葉菜類，以播種方式栽培，多為密植。光會直接影響植物的氮循環系統，為生產低硝酸根離子含量之小白菜，須了解其合適之栽培密度、光強度等各項特性。試驗結果顯示當栽培密度為5×4 cm時小白菜植株生長受到影響，鮮乾重較栽培密度為5×10 cm時顯著減少6-15 %，同時其總可溶性糖的累積也較低，植體累積之硝酸根離子含量則提高22-41 %，以5×6-5×8 cm行株距較佳。低光強度會嚴重影響植株生長，在光強度≦200 μmol/m^2/s時小白菜植株鮮乾重及總可溶性糖含量下降，較光強度為800±25 μmol/m^2/s時顯著減少21-43%及24-35%，而硝酸根離子含量於光強度≦200 μmol/m^2/s時則快速累積，較對照組增加32-58 %。以葉綠素螢光參數與植株生理反應比較結果顯示參數ETR、qp、ΦPSII、NPQ均可作為有效參數，當光強度降低時，植株的硝酸還原酶（nitrate reductase）、麩胺醯胺合成酶（glutamine synthetase）活性均隨之上升。

關鍵字

光強度；葉綠素螢光；硝酸根離子；栽培密度；產量；小白菜

並列摘要

Light directly affects the nitrogen cycle during plant growth. This study investigatedthe effects of light quality and intensity on plant growth and examine the light conditions under which a low nitrate content is obtained in Pak-choi plants. The results showed that the plant fresh and dry weights significantly decreased by 6-15% with a 5×4 cm planting density, the total soluble sugar content decreased, and the nitrate content increased by 22-41% as compared with plants grown at a higher planting density. The appropriate row spacing varied according to the cultivar, the suitable spacing being between 5×6 and 5×8 cm for the tested Pak-choi cultivars. When plants were grown under a low light intensity (≦200 μmol .m-2 .s-1), the plant weight and total soluble sugar content were significantly reduced, by 21-43% and 24-35%, respectively, and the nitrate content was increased by 32-58%. Comparing the indexes of chlorophyll fluorescence parameters (ETR, qp, ΦPSII and NPQ) and plant physiological responses, the result showed that ETR, qp, ΦPSII and NPQ varied with nitrate content. The activities of NR and GS were increased as light intensity decreased.

並列關鍵字

light intensity ； chlorophyll fluorescence ； NO_3^- ； planting density ； yield ； Pak-choi

國際替代計量

栽培密度及遮陰對小白菜（Brassica campetstris L. Chinensis group）生長及硝酸根離子含量之影響

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