Effects of Moisture Stress on Germination of Fiber Crops Utilized As Forage.

The recent legalization of industrial hemp (Cannabis sativa L.) on a limited basis has led to a considerable research on its use in alternative markets. One area in which it may have potential is its use as a forage crop. In University of Kentucky variety trials hemp was capable of produced more forage over a 48 day period than warm-season annual grasses. However, these annual grasses had greater total yields due their ability to produce regrowth from tillers that resulted in multiple harvests. Since the growth habit of fiber crops allows for less regrowth, multiple crops may be required to produce equivalent forage yields, but here is little information about the establishment of hemp and other fiber crops during the dry conditions that are common during the summer months. This study examined the ability of fiber and forage crops to germinate over a range of osmotic potentials to simulate water stress that may occur during an establishment late in the growing season. The germination of three fiber crops (kenaf, hemp, and sunn hemp) and two annual forage species (sorghum-sudangrass and cowpea) over five levels of osmotic potentials (ψs). Polyethylene glycol was used to simulate osmotic potential that covered the approximate range of a soil at field capacity (~0.33 Atm) to permanent wilting point (~15 Atm) . As expected, the germination potential for all species declined with greater ψs and appeared to be correlated with seed size. Cowpea had the lowest germination rate across all ψs, whereas hemp and sorghum-sudangrass had the highest. Hemp seed showed the greatest potential to germinate under dry conditions and had 57% germination at 10 Atms compared to < 20% for the other crops. This suggest hemp may have potential as a late season crop but more research is needed focusing on plant development inter these conditions.