苗期春化處理對夏季花椰菜生長與產量之影響

Abstract

花椰菜（Brassica oleracea var. botrytis L.）為十字花科綠植株春化型冷涼季蔬菜作物，在30℃以上高溫，花球發生生理障礙，造成品質不良與經濟損失。本研究以夏作耐淹水品種‘嬌雪’與夏作不耐淹水品種‘農生45天’為試驗材料，於25℃生長箱育苗3-8週後，分別經17/15℃與20℃春化處理0-6週，並配合明暗週期16/8h；於25℃所育3週苗經17/15℃春化2週者，其90%以上植株莖頂直徑達花球創始標準0.6mm為各處理中最快，故後續均以17/15℃為春化溫度。兩品種於25℃所育3週苗，無論有無春化處理，栽培在臺北臺大35/30℃人工氣候室，皆無法結成花球，且葉數減少、葉片Fv/Fm值較低、下位葉葉緣白化；而兩品種於25℃所育3週苗未經春化處理，定植於25/20℃人工氣候室後22d即可採收花球。‘嬌雪’以6種方法做育苗春化處理後，在夏季定植於臺北溫室中，於25℃所育3週苗經17/15℃春化2週之單株花球重218g最高，且全程僅需83d；‘農生45天’於25℃所育3週苗未經春化處理，在夏季定植於臺北溫室，栽培全程僅需81d，且其單株花球155g比溫室苗高。而兩品種於夏季定植在臺南溫室，於25℃所育3週苗全程需101天最短，且‘嬌雪’單株產量344g與其他5處理間沒有差異，‘農生45天’則以於溫室所育未經春化之4週苗，其單株產量338g顯著較高。綜上，花椰菜‘嬌雪’與‘農生45天’在夏季於25℃所育3週苗可不經春化即定植於25/20℃，栽培全程僅需43天。在夏季臺北溫室栽培‘嬌雪’，可採用於25℃所育3週苗經17/15℃春化2週者，栽培‘農生45天’可採用於25℃所育3週苗。夏季在臺南栽培兩品種則可於溫室一併育苗及土耕。‘嬌雪’之低溫春化需求比‘農生45天’高、熱馴化能力比‘農生45天’低。 Cauliflower (Brassica oleracea var. botrytis) is a cool-season vegetable crop of green-plant vernalization type in family Brassicaceae. At temperatures over 30℃, the curds show physiological disorders resulting in low quality and economic loss. In this study, heat- and flood-tolerant 'Charming Snow' as well as heat-tolerant and flood-intolerant 'Nong-Sheng 45 days' were used as experimental materials. Seedlings raised at 25℃ for 3-8 weeks were vernalized at 17/15℃ or 20℃ with light/dark period 16/8 h for 0-6 weeks. Three-weeks seedlings raised at 25℃ and vernalized at 17/15℃ for 2 weeks showed the earliest over 90% seedlings reaching the standard of the curd initiation, 0.6 mm diameter of stem apices. Temperature 17/15℃ thus was used for vernalization in following experiments. The seedlings raised at 25℃ with or without vernalization of 2 cultivars formed no curd after transplanting to 35/30℃ phytotron at Taipei. These plants also showed shriveling stem apices, less leaves, lower Fv/Fm values, and bleaching in the margin of lower leaves. However, 3-weeks seedlings raised at 25℃ without vernalization of 2 cultivars could be harvested on 22 d after transplanting to 25/20℃ phytotron at Taipei. Six methods of raising seedling and vernalization were treated on 2 cultivars before transplanting in Taipei greenhouse in summer. Three-weeks seedlings raised at 25℃ and vernalized at 17/15℃ for 2 weeks of 'Charming Snow' exhibited the highest curd weight per plant of 218 g in totally 83 days. While for 'Nong-Sheng 45 days' transplanted in Taipei greenhouse in summer, 3-weeks seedlings raised at 25℃ without vernalization only needed totally 81 days with curd weight per plant of 155 g higher than greenhouse-raised seedlings. Both cultivars transplanted in Tainan greenhouse in summer, 3-weeks seedlings raised at 25℃ without vernalization needed totally 101 days of planting. For 'Charming Snow', curd weight per plant of 344 g was not different with other 5 treatments. For 'Nong-Sheng 45 days', non-vernalized 4-weeks seedlings raised in greenhouse showed the highest curd weight per plant of 338 g. In conclusion, 3-weeks seedlings raised at 25℃ and transplanted to 25/20℃ of both cultivars only needed 43 days from seeding to harvest. Planting in Taipei greenhouse in summer, 3-weeks seedlings raised at 25℃ followed by vernalization at 17/15℃ for 2 weeks in 'Charming Snow' and 3-weeks seedlings raised at 25℃ in 'Nong-Sheng 45 days' were suggested to use. Both raising seedlings and cultivating in Tainan greenhouse in summer were applicable for both cultivars.