利用產期調控與田間排水以管理茭白基腐病

Abstract

自1999 年起，台灣南投縣栽培之茭白每年夏季均會發生由Pythiogeton zizaniae 或Enterobacter cloacae 所引起之基腐病（basal stalk rot 或basal stem rot）。田間病害調查顯示，本病害主要發生於“早生青殼”品種之茭白，尤其 在7 月時最為嚴重，發病度可達 43.8%。該品種茭白栽培期為12 月開始育 苗種植至翌年10 月，有兩次採筍期為4-6 月及7-10 月上旬，分別稱為第一與第二期筍，而基腐病主要減少第二期筍的產量。本研究指出不採收第一期筍或在第一期筍採收時全期排水，可降低基腐病的發生；若在採收第一期筍中末期（5-6 月）排水 30-40 天，雖對第一期筍的產量有輕微影響，但能降低基腐病的危害而減少第二筍期產量的損失。為確保第一期筍的產量，本研究亦提出茭白筍產期調節的方法，即提早 1 個月（於11 月上旬）育苗種植，並在分蘗生長期間實施夜間照光以避免矮化症，則能使第一期筍提早於4 月採收完畢，爾後排水則不影響第一筍期的產量。此外，若於排水期（5-6 月）將地上部枝葉全部割除，使分蘗苗重新長出，則發病度可低至0.4%，顯著較僅排水處理組 9.1% 與慣行浸水對照組 13.2% 低。 Basal stalk rot (or basal stem rot) caused by Pythiogeton zizaniae and/or Enterobacter cloacae was a serious disease of water bamboo (Zizania latifolia (Griseb.) Turcz. ex Stapf.), which occurred in summer and caused considerately economic loss each year in Nantou county since 1999. The results of field investigation showed that the major local cultivar ‘Green Shell Early’ of water bamboo was very susceptible with disease severity as high as 43.8% in July. The regular plantation periods of time, including two harvest seasons, were about ten months from December to October of the next year. The first harvest season (1st season) is form April to June and the second (2nd season) from July to October. The basal stalk rot disease was more advanced in the 2nd season. Results of studies showed that the disease in the 2nd season significantly decrease in the treatments without harvesting in the 1st season or with drainage for 30-40 days at the late period of the 1st season. In order to avoid the yield loss in the 1st season caused by drainage, the technique that early planting (in November.) plus night lighting treatment during the seedlings stage (from November through February) was developed for harvest season regulation. This treatment could promote the 1st harvest season (March to April) about 1 month earlier, which would make up the yield loss due to drainage in the 1st season. Furthermore, the method treated with drainage and cut-off all the above ground plants post the 1st season would assist new tillers growth and significantly reduce basal stalk rot disease. The disease severity of treatment using this method was only 0.4%, which was significantly lower than those of merely drainage treatment (9.1%) or non-drainage (13.2%).