Desiccation tolerance in relation to soluble sugar contents in seeds of ten coffee (Coffea L.) species

Large differences in seed desiccation sensitivity have been observed previo usly among ten coffee species (Coffea arabica, C. brevipes, C. canephora, C . eugenioides, C. humilis, C. liberica, C. pocsii, C. pseudo-zanguebariae, C. sessiliflora and C. stenophylla). Of these species, C. liberica and C. h umilis were the most sensitive to desiccation and C. pseudozanguebariae the most tolerant. A study was carried out using the same seed lots to investi gate if these differences in desiccation tolerance could be correlated with differences in soluble sugar content. Soluble sugars were extracted from d ry seeds and analysed using high performance liquid chromatography. The see d monosaccharide (glucose and fructose) content was very low (1.5 to 2 mg g (-1) dry weight [dw]) in all species studied. The sucrose content ranged fr om 33 mg g(-1) dw in C. liberica seeds to 89 mg g(-1) dw in seeds of C. poc sii. Raffinose was detected in the seeds of only five species (C. arabica, C. brevipes, C. humilis, C. sessiliflora, C. stenophylla), among which only three species (C. arabica, C. sessiliflora and C. brevipes) also contained stachyose. Both raffinose and stachyose were present in very low quantitie s (0.3-1.4 mg g(-1) dw and 0.1-0.7 mg g(-1) dw, respectively). Verbascose w as never detected. No significant relationship was found between seed desic cation sensitivity and: (i) the sugar content; (ii) the presence/absence of oligosaccharides; and (iii) the oligosaccharide:sucrose ratio.