苗齡對千里香辣椒穴盤苗乾物質變化及氮素含量之影響

Effect of Seeding Age on Dry Matter and Nitrogen Content of Transplanted Chili Pepper 'Everflavor' (Capsicum annuum L.)

春季以不同苗齡（30、34、38、42及46天）‘千里香‘辣椒幼苗定植時，苗株地上部、根部及全株乾重以38天以上大苗齡顯著較30天及34天苗為高，定植後差異減小或不明顯。乾重累積同，以30天苗增加最快，以定植後4週之乾重為基準，定植後l、2、3週根部分別累積第4週根乾重之28%、41%及76%；地上部分別累積第4週莖葉乾重之17%、24%及47%，而46天苗的根部與地上部乾重累積，在定植後1、2、3週分別為16%、27%及91%（根部）與10%、16%及44%（地上部）。就乾物質在不同部位之分配，定植時除30天苗以葉片乾物質分配較多外，其它苗齡以莖部多，乾物質分配達46-53%，30天苗在定植後前3週及34天苗在定植後1週有20%全株乾重在根部，其它苗齡苗根部所佔乾重均在20%以下，並隨定植後週數增加而逐漸降低，在葉片的乾物質百分比率先呈增加再下降，同時氮素濃度、含量也增加。秋作辣椒不同苗齡（24、28、32及36天）之乾物質累積在定植時，以36天苗顯著較其它苗齡苗為高，到定植後第4週只有24天苗乾重較低，其它苗齡苗沒有顯著差異，就累積速率，根部在定植前一週即有較大量之累積，莖葉乾重在定植後才有大量增加，各苗齡間沒有顯著差異；定植時乾物質分配在24、28及32天苗均以葉部較莖部高，介於40-44%，36天苗葉部乾重佔全株乾重36.8%，莖部佔40.9%，其它苗齡苗莖部佔全株乾重之34-39%。定植後5週內乾物質均以莖、葉為主要部位，根系所佔比率大減，葉片氮濃度及含量亦在定植後增加，但36天苗在定植3週以後，氮濃度降低，葉片氮含量較28天及32天苗為低。大齡苗或苗株需作較久留置，必須注意氮素供應。以5℃或10℃為基礎溫度。試驗期間由每日平均溫度所累積溫度與到全株乾物重呈二次正相關。

Dry mutter (DM) accumulation and distribution were studied on chili pepper 'Everflavor' seedlings of different ages at and after transplanting. The seedling age was counted as days after cotyledon unfolding. Five seedling ages (30、34、38、42 and 46) were included in spring crop. At transplanting, seedlings of and older than 38 days of age had significantly higher root, shoot and whole plant dry weight than seedlings of 30 or 34 days of age. After transplanting, there were no significant difference among seedlings of different ages in terms of dry weight accumulation. However, the DM accumulation rate was the highest in seedlings of 30 days of age. At 1、2 and 3 weeks after transplanting (WAT), roots of 30 day seedlings accumulated 28%、41% and 76%, respectively, of the DM at 4 WAT. The corresponding values for shoots were 17%、24% and 47%. The DM accumulation rates far 46 day seedlings were 16%、27% and 91% in roots and 10%、16% and 44% in shoots at 1、2 and 3 WAT. At transplanting, plant DM was mostly partitioned to stems, Ca. 46-53% for all seedlings in spring crap except for 30 day ones which had mast DM distributed to the leaves. As time progressed after transplanting, the percentage of DM distributed to the roots decreased in seedlings of 38、42 and 46 days of age. The 30 day seedlings had 20% of DM distributed in roots at 1-3 WAT. The 34 day seedlings also had 20% of DM in roots at 1 WAT. Alt other seedlings had less DM in roots. The percentage of DM allocated in leaves increased first upon transplanting and decreased later. At the same time, the N concentration and contents increased as time progressed. In fall crop, the seedling dry weight was proportional to seedling age. At transplanting, the 36 day seedlings accumulated significantly higher DM than other seedlings. At 4 WAT, the 24 day seedlings had the lowest dry weight, while the other seedlings had no significant difference. As for DM accumulation pattern, the roots had large accumulation one week before transplanting and the shoots accumulated significantly only after transplanting. No significant difference was observed in seedlings of different ages. Plant DM at transplanting was mostly distributed to the leaves ca. 40-44% in seedlings of 24, 28 and 32 days of age. About 34-39% of DM was distributed in stems. The 36 day seedlings had 36.8% and 40.9% of DM partitioned in leaves and stems, respectively. The percentage of DM distributed to roots continued to decline after transplanting. At 5 WAT, plant DM was allocated mostly in shoots. The N concentration and content in stems and leaves increased after transplanting. However, the N concentration reduced in 36 day seedlings after 3 WAT, The leaf N content was thus lower than those of 28 and 32 day seedlings. Before transplanting, N supply would be critical to old seedlins. Accumulated heat with base temperature of either 5℃ or 10℃ was positively correlated with seedling biomass dry weight.