Caryopsis and spikelet characteristics related to germination behavior in Digitaria californica

Abstract

Digitaria californica is a warm-season grass native to western hemisphere deserts. This study was conducted to measure: (1) seed dormancy, and the effects of (2) wetting and drying on germination, and (3) glumes on water uptake and loss. Dormancy was measured with weekly germination trials for 12 weeks. Complete and naked caryopses were exposed to a 24-h dry period after 12, 24, 36, and 48-h imbibition, and rewetting for 2 weeks. Water uptake and loss patterns were also measured. Germination percentage increased from about 40% initially to 94% after 9 weeks. Germination speed decreased from 5 days to about 2 days over the same period. Drying reduced percent germination of the 36- and 48-h imbibition treatments for complete caryopses, and that of the 24-, 36-, and 48-h imbibition treatments for naked caryopses. Complete caryopses also seemed to imbibe faster. Moisture loss for complete and naked caryopses appeared similar. Short imbibition periods do not induce germination in this species.