應用低溫弱光維持置留期草莓穴盤苗品質

Abstract

本研究旨在探討適合草莓穴盤苗的置留期的儲藏放置條件，以在定植前維持種苗的品質。最佳置留期儲藏條件為5℃＋50 μmol·m⁻²·s⁻¹/12 h，換算光積值為2.16 mol·m⁻²·day⁻¹。苗齡24天的‘桃園一號’苗，儲藏3週與6週後，苗株冠莖直徑、走莖及葉片增長量低，葉片及根生長無明顯劣變。苗齡38 天的苗儲藏後品質與小苗類似，惟儲藏6 週後17%的苗失去商品價值；因此，24天的苗齡為推薦的冷藏時機。由於苗株在5℃+50 μmol·m⁻²·s⁻¹的儲藏期間仍有少量生長，依生物量的變化推測，在5℃下草莓苗的光補償點應低於50 μmol·m⁻²·s⁻¹，推測可藉由縮短光照時數降低光積值達到控制生長的目的。低溫弱光置留1-6週植株，出庫後均可於1週後快速恢復生長。未經低溫弱光置留處理的草莓穴盤苗，在生長箱模擬溫暖環境 (28℃/25℃+250 μmol·m⁻²·s⁻¹/12 h) 以及溫室模擬高溫環境(31℃/27℃+380 μmol·m⁻²·s⁻¹/12.5 h) 下置留，苗株會因為地上部過度生長及盤根而劣變，並且株齡38天的苗更為嚴重。地上部過度生長會造成相互遮蔽、光合作用降低，導致葉片黃化。此外，5℃＋50 μmol·m⁻²·s⁻¹的置留條件，也可應用於‘桃薰’草莓穴盤苗的生產。置留處理對產果的影響試驗始於2023年10月12日，試驗地點為臺灣大學園藝分場的溫室，試驗前4週溫度較高，均溫約為26℃，5-22週均溫介於18-22℃，爾後溫度急遽上升，試驗於2024年4月18日結束，總計栽培26週。未置留植株從第6週起總共開四期花，低溫弱光置留處理花期延後，置留時間越長、越晚開花。置留≧4週者總花期數減少，但植株至試驗結束皆維持生長旺盛。/因此，在類似環境中生產果實，欲避免因花期延後而減少花序數，儲藏時間不宜超過3週。

This study aims to determine the adequate storage conditions for holding period of strawberry plug plants in order to maintain plant quality prior to transplant. The best storage condition was 5°C+50 μmol·m⁻²·s⁻¹/12h which resulted in a daily light integral of 2.16 mol·m⁻²·day⁻¹. The 24 days old ‘Taoyuan No. 1’ plug plants showed no significant morphological change after 3 or 6 weeks of storage, slightly increase of crown diameter,runner and leaf number, no deterioration of leaf and root system. Similar storage result was obtained in the 38 days old plug plants, but 17% of the plants lost marketable quality after 6 weeks of storage. Therefore, the plug plants of 24 days old is recommended for storage. The slightly growth under 5°C+50 μmol·m⁻²·s⁻¹/12h revealed that the light compensation point of strawberry at 5°C might higher than 50 μmol·m⁻²·s⁻¹ and suggested reducing daily light integral by shortening the lighting hours could be an approach to solve the problem. The growth of the stored plug plants resumed quickly within 1 week after removal from storage condition. A growth comparative study of the plug plants holding at simulated regular (28°C/25°C, 250 μmol·m⁻²·s⁻¹/12h) and high temperature greenhouse (averaged at 31°C/27°C, 380 μmol·m⁻²·s⁻¹/12.5h) conditions showed deteriorated effect on plant quality due to shoot over growth and circling roots,and the deterioration was much severe in 38 days old plants. In addition, the over growth resulted leaf shading, photosynthesis reducing and leading to leaf yellowing and necrosis. The storage condition of 5°C+50 μmol·m⁻²·s⁻¹/12h was also applicable for ‘Toukun’ strawberry plug plants production. The effects of storage on fruit production was conducted in a greenhouse at the Horticulture Research of National Taiwan University since October 12, 2023. The average temperature of the first 4 weeks was relatively high, at approximately 26°C, and which was ranged between 18°C-22°C between weeks 5 to 22. The evaluation was stopped at 26th weeks, April 18, 2024, due to the temperature increased rapidly. Nonstored plants began flowering in the 6th week and produced a total of four cluster of fruits. The flowering was delayed due cold storage, the longer they stored the later they flowered. The plants stored ≥ 4 weeks produced fewer clusters in general, although they displayed more vigorous vegetative growth throughout. Therefore, to avoid a reduction in crop number caused by delayed flowering under similar environmental conditions, the storage duration should not exceed 3 weeks.