The perennial, desert saltgrass Distichlis stricta is very widespread in North America. Because of its reproductive capacity (mainly by rhizomatous spread) and grazing potential, it offers potential for revegetating disturbed areas in arid southwestern USA. In this laboratory study, various trials were undertaken to assess best techniques for vegetative propagationfrom rhizomes.
Fresh saltgrass rhizomes for the trials were collected near San Ysidro (New Mexico). A series of trials were undertaken to determine best propagation and storage regimes.
Temperature: 1-, 2-, and 3-node sections (averaging 2.5, 5.5 and 9.5 cm in length respectively), were randomly placed in trays of moist perlite under a 5°C increment temperature regime (10 to 40°C) for 4 weeks. The number of sprouting rhizomes was recorded.
Storage: Rhizomes were washed and stored in 10 x 23 cm sterile polyethylene bags (5, 1-node rhizomes/bag; 5 bags/treatment) at temperatures from -10 to 23°C for 1, 2, 3 or 4 weeks. At weekly intervals, rhizome batches were planted and maintained at 25°C. Survival (bud sprouting) was evaluated after 28 days.
Desiccation: Effects of desiccation on viability were determined on 1- and 2-node rhizome sections. Fresh weight was recorded prior to placing into trays subject to air drying (22°C; relative humidity 45-60%) for 1 to 24 h. Rhizomes were reweighed (to assess water loss), then covered with moist perlite (maintained at 25°C) for 28 days to assess sprouting capacity.
Osmotic stress: Effects of osmotic stress were evaluated on 1-node rhizomes in NaCl solutions from 0.05 to 0.50 M at 25°C.
Temperature: Optimum temperature for rhizome growth was 25 to 30°C. No clear relationship was found between length of a rhizome section and sprouting capacity.
Storage: At 2 and 10°C sprouting percentages were in excess of 65% after 28 days. All died at -10°C prior to day 7; at 15°C survival was 36% at day 21 but zero at day 28; at 23°C survival was 76% at day 7 but none survived subsequently.
Desiccation: 1-node sections lost water more quickly than 2-node sections. A marked reduction in rhizome sprouting (40% or less) occurred when moisture loss exceeded 35% (down to highest loss 44%) initial weight. Above this sprouting was 70-100%.
Osmotic stress: Survival ranged from 53% (0.40 M) to 93% (0.05 M) over the osmotic potentials tested, suggesting that saltgrass rhizomes can tolerate a wide range of osmotic and water potentials.