杧果种子的脱水与贮藏研究

STUDIES ON DESICCATION AND STORAGE OF MANGO SEEDS

杧果(Mangifera indica L.)种子是顽拗型种子(Recalcitrant seed),刚采收时含水量高达69.2—75.5%(其胚轴含水量为73.8—86.3%),在室温空气中凉干8天后,含水量下降至39.1%(胚轴含水量降至46.5%),发芽率由100%降至0。胚轴含水量下降比整粒种子慢。杧果种子在室温空气中凉干时,随脱水程度的增加,浸种液电导率从2.2μΩ·cm^(-1)·g^(-1)(单位下同)迅速上升至56.7,而胚轴中脱氢酶及酸性磷酸黪活性却迅速下降。用电扇吹风(快速干燥)42小时,种子含水量由75.5%迅速降至29.9%,浸种液电导率从1.8迅速增加至36.9,发芽率由100%降至10%。脱水损害细胞膜完整性及降低酶活性,快速脱水对膜完整性的损害比慢速脱水轻。杧果种子的离体胚轴经硅胶干燥8小时后含水量降至11.8%,在 MS+0.2mg/L BA+2.0mg/L NAA+500mg/L Gin+3%蔗糖+0.9%琼脂培养基上还有80%发芽率。将种子用电扇吹风10小时使含水量达到51.0%,将此含水量种子用塑料袋密封,于15℃下贮藏7个月还有65%发芽率。

Mango (Mangifera indica L.) seed is recal itrant which taken from ripened fruits con- ained as high as 69.2-75.5% moisture content (The moisture content of embryonic axis is 73.8- 86.3%).When seeds were naturally dried for 8 days,the moisture content declined to 39.1% (in embryonic axis the moisture content declined to 46.5%) and the viability of seeds completely lost.Embryonic axis lost water slower than whole seed because of the prevention of desicca- tion by the large cotyledons.During natural desiccation,the conductivity of leachate increased apidly from 2.2μΩ·cm^(-1)·g^(-1) (the same unit below) to 56.7,whereas the activities of dehy- drogenase and acid phosphatase decreased drastically.When seeds were rapidly dried for 42 hours,the moisture content declined from 75.5 to 29.9%,the conductivity of leachate increased from 1.8 to 36.9 and the percentage germination changed from 100% to 10%.Desiccation da- maged the cell membrane and decreased the activities of enzymes.Rapid drying was better for maintaining longevity than natural (slow) drying because the former did less damage to the cell membrane than natural (slow) drying as shown in the conductivity changes.The moisture content of excised embryonic axis decreased to 11.8% when they were dried for 8 hours by silicagel.The survival percentage of these embryonic axis was 80% when they were incubated in MS+0.2 mg/L BA+2.0 mg/L NAA+500 mg/L gln+3% sucrose+0.9% agar me- dium.Seeds with 51.0% moisture content (rapidly dried for 10 hours by electric fan blowing) had 65% viability after 7 months wet storage with the polyethylene bag at 15℃.