Field experiments were conducted to investigate the seed attributes, movements and fates of dispersal units, and seedling establishment of Chrysopogon aucheri and Cymbopogon jwarancusa in a representative grassland ecosystem in upland Balochistan, Pakistan. Cymbopogon jwarancusa had more filled and viable caryopses than Chrysopogon aucheri. Seeds (spikelets) of both species had similar morphological features. Chrysopogon aucheri had one dispersal unit, a triplet spikelet. Cymbopogon jwarancusa had four types of dispersal units: a paired spikelet, a partial raceme, an entire raceme, and a partial inflorescence comprised of two racemes. Paired spikelets and partial racemes of Cymbopogon jwarancusa had greater mean dispersal distances (94 and 101 cm) from the edge of the basal crown of marked plants to the ground surface than triplet spikelets of Chrysopogon aucheri (79 cm). Spikelets of Cymbopogon jwarancusa and Chrysopogon aucheri moved mean distances of 26 and 32 cm, respectively, on the ground surface before becoming trapped in a microhabitat. The mean angle of dispersal for both species was toward the northeast, according to the prevailing wind direction. An ant (Tica verona) was the only detected seed (spikelet) predator for Chrysopogon aucheri. Both species had a weakly persistent soil seed bank, with higher amounts of seeds found under plant canopies compared to open interspaces. The recruitment of Chrysopogon aucheri and Cymbopogon jwarancusa seedlings from the natural seed bank was monitored in seven different microhabitats under natural and above-normal precipitation regimes . Above-normal precipitation increased seedling recruitment for both species in all microhabitats. Cymbopogon jwarancusa had higher seedling densities than Chrysopogon auchfiri. Seedling survival and tiller development for both species were greatest in the gravel microhabitat in the natural precipitation treatment. Monsoon rains in late July enhanced emergence of both species from recently dispersed seeds but emerged seedlings did not survive to the end of the growing season. The field studies indicate that Cymbopogon jwarancusa has a greater regeneration potential than Chrysopogon aucheri in this grassland ecosystem in upland Balochistan. It may be difficult to increase the composition of Chrysopogon aucheri, the more desirable species in these grasslands, when using management techniques that rely on natural regeneration .

Controlled environment experiments were designed to study the germination, seedling development, and defoliation responses of Chrysopogon aucheri and Cymbopogon jwarancusa to better understand their xv autecology and potential use in range improvement programs in Baluchistan. In experiment 1, Cymbopogon jwarancusa had greater seed fill and viability than Chrysopogon aucheri. When incubated at six different alternating temperature regimes, seeds of Cymbopogon jwarancusa had greater cumulative germination at five temperature regimes and faster germination at the colder temperature regimes than Chrysopogon aucheri. In experiment 2, seedling shoot and root development was characterized at 15-day intervals over a 60-day period. Seedlings of both species had a "panicoid'' type seedling morphology. Chrysopogon aucheri and Cymbopogon �warancusa developed comparable numbers of leaves and tillers per plant during the 60-day period. Chrysopogon aucheri had a greater number, length, and dry weight of primary and seminal roots than Cymbopogon jwarancusa at 30 and 60 days, respectively. Adventitious root length was also higher for Chrysopogon aucheri than Cymbopogon jwarancusa at 60 days. Seedlings of both species had similar shoot:root ratios and relative growth rates. In experiment 3, seedlings of both species were planted in rnonocultures and in a 50:50 mixtures. Defoliation treatments, implemented 32 weeks after emergence, included: equally clipping all plants of both species zero, one, two, or three times (at 4-week intervals) in monoculture and mixture; and clipping one species zero, one, two, or three times (at 4-week intervals) without clipping the associated species in mixture. Both species remained vegetative and did not differ in leaf and tiller development until about 32 weeks after emergence. During later growth, Chrysopogon aucheri reproduced while Cymbopogon jwarancusa remained vegetative. cymbopogon jwarancusa produced more tillers on control plants and defoliated plants (mainly in monoculture). At lower frequencies of defoliation Chrysopogon aucheri produced more shoot and root biomass than Cymbopogon jwarancusa (mainly in mixture). In 50:50 mixtures when one species was defoliated and the other not, both species were comparable in shoot dry weight; however, Chrysopopgon aucheri was superior to Cymbopogon jwarancusa in root dry weight at all defoliation regimes. The initial standing crop and subsequent regrowth of Chrysopogon aucheri were comparable or higher in crude protein and digestibility than Cymbopogon jwarancusa.