Accumulation of sugars during the onset and development of desiccation tolerance in immature seeds of Norway maple (Acer platanoides L.) stored moist

The viability of Norway maple seeds collected 21 d before mass maturity (68%moisture content, wet basis) and at mass maturity (56% moisture content) was reduced from 52–85% to 0–7% if dried rapidly (at 10–12% r.h. and 15–17°C for 3 d, then 3 d over silica gel) to 4–5% moisture content. Moist storage of the fruits at 15°C improved the ability of the seeds to tolerate rapid desiccation considerably: 10 and 21 d of moist storage enabled seeds collected at mass maturity or 21 d earlier, respectively, to attain maximum desiccation tolerance to 4–5% moisture content. Moist storage and/or subsequent desiccation affected stachyose, sucrose, and to a lesser extent raffinose, concentrations. The oligosaccharide:total sugar ratio showed a similar pattern in relation to ability to germinate after desiccation to 4–5% moisture content among seeds collected on both dates: desiccation tolerance developed from nil to maximal in these seed populations between threshold oligosaccharide:total sugar values of just less than 0.3 and about 0.4.

Germination Behavior of Florida Pusley Seeds. I. Effects of Storage, Light, Temperature and Planting Depths on Germination

Freshly harvested Florida pusley (Richardia scabraL.) seeds do not germinate in continuous dark, but do germinate if exposed to more than 2 hr of light each day. Increasing periods of illumination up to 16 hr per day increases the germination percentages. Scarification increases the rate of germination in the presence of light. Scarification also causes germination of seeds stored for 8 months or longer in total darkness. The seeds fail to germinate at constant temperatures of 15 C or less and at 40 C. Almost complete germination occurs at a constant temperature of 30 C, or at alternating temperatures of 20 and 30 C. The seeds germinate equally well in the pH range of 3 to 8. Increasing depths of planting reduces percent emergence, and none of the seedlings emerge from a depth of 1.5 cm or more. Air-dried seeds can be stored either at 5 or at 25 C without losing viability, at least up to a period of 1 year after harvest. Moist storage of seeds at 5 C reduces germinability.

GREEN FOXTAIL: SEED DORMANCY, GERMINATION AND GROWTH

Green foxtail seed exhibited complete or near-complete dormancy when freshly harvested. This dormancy was overcome most readily during moist storage at 6 C for three to six weeks. Seed germination occurred over a wide range of temperature, but most rapidly at or above 25 C. Seedlings emerged readily from planting depths up to 8 cm. Plants emerging as late as the end of July could still produce seeds during the same season. Implications of the findings for green foxtail control are discussed. Severely restricted growth of green foxtail under reduced temperature and light intensity is considered to account for at least part of the reported low competitive efficiency of green foxtail infestations in field crops in western Canada.