番木瓜種子休眠性可由變溫、激勃素及Karrikin-1打破

番木瓜（Carica papaya L.）為一、二年生栽培的熱帶果樹作物，主要以種子實生繁殖。然而，番木瓜種子因具有休眠性，常造成發芽不整齊及發芽率不穩定的現象，影響種苗生產。本試驗目的在探討浸潤方式、激勃素（Gibberellins; GAs）、硝酸鉀、培養溫度條件及karrikin-1（KAR1）對番木瓜種子發芽的影響及其交互作用，以了解影響發芽的關鍵因子。番木瓜種子浸潤後以100 mg∙L-1 GA4+7處理24小時能有效促進發芽，提高種子發芽率及發芽整齊度。室外培養或30/26°C變溫處理也能有效促進番木瓜種子發芽，但GA4+7會使種子對30°C高溫敏感，發芽受到抑制且胚根及下胚軸畸形。硝酸鉀及浸潤方式無法促進番木瓜種子發芽，幾乎不影響GA4+7或變溫對種子發芽的效應。低濃度KAR1能再提高變溫或GA4+7處理之番木瓜種子發芽的促進效果。種子以1 nM KAR1浸潤，可顯著提高30/26°C變溫培養的發芽率，由40%增加為60%，10 μM KAR1則反而有抑制效果；但其濃度效應會受到GA4+7處理而改變。

關鍵字

番木瓜；發芽；休眠；激勃素； karrikin

並列摘要

Papaya（Carica papaya L.）,an important tropical fruit crop cultivated annually or biennially, is propagated mainly by seeds. However, the dormancy of papaya seeds usually causes the ununiform and unstable germination. The aim of this study was to unveil the key factors affecting germination of papaya seeds and their possible interactions, between imbibition, gibberellin, alternating temperature, potassium nitrate, and karrikin-1（KAR1）. Seeds treated with 100 mg∙L-1 Gibberellin A4+A7（GA4+7）after imbibition for 24 hours showed high percentage and uniformity of germination. Outdoor incubation or alternating temperature of 30/26°C also stimulates the germination of papaya seeds, but deformation of radicles and hypocotyls, and lowered percentage of germination were observed in seeds treated with GA4+7. Potassium nitrate and ways of imbibition did not stimulate germination, and without interfere the promoting effects of gibberellin and alternating temperature. Dilute solution of KAR1 can improve the promoting effects of alternating temperature and gibberellin on germination. Seeds imbibed with 1 nM KAR1 significantly increase the percentage of germination under alternating temperature, and 10 μM KAR1 showed inhibitory effect, while such concentration effect may be altered by gibberellin.