Field evaluation of switchgrass seedlings divergently selected for crown node placement

Excessive crown node elevation of warm-season grass seedlings is a major li mitation to successful establishment. Crown node placement at or above the soil surface limits the opportunity for adventitious root development at th e crown node. Switchgrass (Panicum virgatum L,) germplasm selected for low- (LC) and elevated- (EC) crown node placement (at 1.5 mu mol m(-2) s(-1) ph otosynthetic photon flux density), has been developed from 'Alamo' switchgr ass, The objective of this study was to determine if differences in crown n ode placement and other seedling morphological traits exist among Alamo (no nselected, parental), LC, and EC germplasm and if these differences affect seedling establishment in the field. Seeds were planted during April and Ma y at Beeville, Stephenville, and College Station, TX, Each location was est ablished with six blocks each consisting of a 2-m row of Alamo, LC, or EC s eed. Seeds were planted at a l-cm depth. Three to 10 seedlings were marked at soil level, then dug for detailed seedling measurements. There were no g enotype by location interactions for any trait measured. Emergence was more rapid at Beeville for all entries because of prewatering and better soil c onditions. Averaged for the three locations, final emergence was 47, 37, an d 30% for LC, EC, and Alamo. Mesocotyl length of LC germplasm averaged 5.9 mm compared with 8.4 and 9.1 mm for Alamo and EC germplasm, respectively. E ven though LC seedlings had shorter mesocotyles and consequently lower crow n node placement than EC or Alamo seedlings, these traits may not be direct ly responsible for greater establishment success.