穴盤苗苗齡對芹菜定植後生長特性之影響

Effects of Seedling age on Growth Character of Celery (Apium graveolens L.) after Transplanting

春作芹菜採用‘海南青’、'Giant Pascal'西洋芹及‘芹菜弄’三個品種，以不同苗齡（36、40、44、48及52天）幼苗定植後之生長特性來評估定植時之苗株品質。苗株品質以三種生長指標評估，相對壯苗指數為「（莖徑／株高）＋（地下部乾重／地上部乾重）」×全株乾重（mg），G值為全株乾重（mg）/育苗天數，葉面積比為葉面積（cm2）/全株乾重（mg）；幼苗定植時之相對壯苗指數範圍為0.02-0.04，以36d苗最小，G值以小苗36、40、44d苗較48及52d苗為大，分別為0.64、0.58、0.53及0.48及0.44.mg•d^(-1)；葉面積比介於223-347，以36d苗最大。定植後以36d及40d苗有較高的相對生長速率。秋植試驗，顯示不同苗齡（24、28、32、36、40及44d）定植後葉數增加相同，葉柄長及葉面積增加以40d及44d苗較快，但到定植後八週，葉柄長為36-42.8cm、莖粗21.6-24.6mm，苗齡間無顯著差異。各苗齡苗之相對生長速率無顯著差異，定植後三到四週期間，生長快速，地上部及根部RGR約0.09-0.15mg‧mg^(-1)‧d^(-1)至第六週後生長減緩。由秋植芹菜定植後之生長評估，穴盤苗苗齡之影響不大，但苗齡越小，定植後的管理越要注意。

Various growth characteristics were evaluated on celery seedlings of different ages both at and after transplanting. In spring, three celery cultivars used were 'Giant Pascal', 'Hai-Nan-Chin' and 'Stemmed Ching'; five seedling ages studied were 36、40、44、48 and 52 days after cotyledons unfolding. Plant growth increased with seedling age in terms of plant height, leaf number, leaf area, basal stem diameter, etc. There was no interaction of seedling ages and cultivars. The growth index of seedling was obtained from[(stem width/hight)+ (root Dw/shoot Dw)]× total Dw (mg), the G value was total plant Dw/seedling growth period ,and the leaf area ratio was leaf area(cm^2)/total Dw(mg). At transplanting, the relative growth index of seedlings ranged between 0.02 and 0.04; G value , another index ,was higher in 36、40 and 44 d seedlings than in 48 and 52 d ones. The corresponding G value for the former seedlings were 0.64、0.58 and 0.53、0.48 and 0.44 mg.d^(-1), respectively. The leaf area ratio ranging between 223 and 347 was highest in 36 day seedling. After transplanting, the 36 and 40 d seedlings had greater relative growth rate (RGR); the best seedling age for celery transplants in spring was not over 44 d. In fall, RGR for all seedlings after transplanting showed no significant differences and ranged between 0.09-0.15mg.mg^(-1)day^(-1). Between the third and the fourth weeks after transplanting, all celery seedlings had fast growth and continued till the sixth week. Afterwards, seedling growth decreased and recessed at the eighth week with petial 36-42.8cm of length and basal stem 21.3-24.6cm of diameter. The results of fall trial indicated that there was no difference in plant growth and seedling vigor among seedlings of different ages. Only the smaller the celery seedling is, the more intensive management care is needed at and after transplanting.