Field evaluation of switchgrass seedlings divergently selected for crown node placement

Excessive crown node elevation of warm-season grass seedlings is a major limitation to successful establishment. Crown node placement at or above the soil surface limits the opportunity for adventitious root development at the 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) photosynthetic photon flux density), has been developed from 'Alamo' switchgrass, The objective of this study was to determine if differences in crown node placement and other seedling morphological traits exist among Alamo (nonselected, parental), LC, and EC germplasm and if these differences affect seedling establishment in the field. Seeds were planted during April and May at Beeville, Stephenville, and College Station, TX, Each location was established with six blocks each consisting of a 2-m row of Alamo, LC, or EC seed. 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 genotype by location interactions for any trait measured. Emergence was more rapid at Beeville for all entries because of prewatering and better soil conditions. Averaged for the three locations, final emergence was 47, 37, and 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. Even though LC seedlings had shorter mesocotyles and consequently lower crown node placement than EC or Alamo seedlings, these traits may not be directly responsible for greater establishment success.