An investigation of recalcitrance in seeds of three native New Zealand tree species.
Recalcitrance in seeds of three New Zealand native tree species (Corynocarpus laevigatus, Griselinia littoralis, Hoheria populnea) was investigated by examining the germination of fruits and seeds that were desiccated following collection. Seeds of Corynocarpus laevigatus and Griselinia littoralis that were allowed to dry in the laboratory showed the reduced percentages and rates of germination typical of recalcitrant seeds, but similarly treated seeds of Hoheria populnea germinated more rapidly and show no decrease in germination after desiccation. The water relations of Corynocarpus laevigatus fruits were examined in greater detail. The bulk of water loss (>50%) occurs in the flesh of the fruit while the fibrous endocarp presents a physical barrier not only to germination but also to both water uptake and loss by the embryo. The water content of embryos is conserved at the expense of the outer layers of the fruit, so that desiccation affects the germination of embryos from intact fruits less than that of either naked embryos or embryos from fruits lacking flesh.