In the establishment-year experiment, MWNC [HF.sub.C2]BRH had greater herbage yield than any of the other MWNC populations selected for root morphology (Table 3).
Positive correlations between fibrous root mass and total herbage yield were found only for FLEM and NCPL in the establishment-year experiment and for NDRN and MWNC in the first-production-year experiment.
No relationship between herbage yield and taproot diameter was found in either the FLEM or MWNC germplasm sources.
However, these three traits were not different between the [BRH.sub.C2] and [TAP.sub.C2] populations in either the FLEM or NDRN germplasm sources or between the [HF.sub.C2]BRH and [LF.sub.C2]TAP populations in either of the MWNC and NCPL germplasm sources.
Mean square for overall analyses for root morphology traits for the MWNC germplasm selected fibrous root mass and lateral root number.
MWNC [HF.sub.c2]BRH and MWNC [HF.sub.c2]TAP were not different in fibrous root mass and had more fibrous roots than MWNC [HF.sub.c1], which in turn had greater fibrous root mass than the rest of the MWNC populations (Fig.
Means for taproot diameter, root weight, and plant number per plot for the MWNC and NCPL germplasm sources selected for fibrous root mass and lateral root number.
MWNC Taproot Root Plant Population([dagger]) diameter weight count number mm g [plot.sup.-1] [plot.sup.-1] [HF.sub.C2] BRH 6.8 32.7 12.9 [HF.sub.C2]TAP 6.9 31.8 12.8 [HF.sub.C1] 6.8 27.6 11.1 Source germplasm 5.9 15.8 9.5 [LF.sub.C1] 6.8 28.5 12.2 [LF.sub.C2]BRH 6.9 32.7 12.7 [LF.sub.C2]TAP 6.7 31.3 13.3 [LSD.sub.0.05] 0.2 2.3 0.7 NCPL Taproot Root Plant Population([dagger]) diameter weight count number mm g [plot.sup.-1] [plot.sup.-1] [HF.sub.C2] BRH 6.4 23.3 11.7 [HF.sub.C2]TAP 6.0 20.7 12.2 [HF.sub.C1] 6.2 19.7 10.9 Source germplasm 6.2 16.9 9.6 [LF.sub.C1] 6.0 17.7 10.8 [LF.sub.C2]BRH 6.1 21.9 12.0 [LF.sub.C2]TAP 6.1 21.4 12.2 [LSD.sub.0.05] 0.2 1.8 0.7 ([dagger]) HF and LF are high and low fibrous root mass, respectively.
Lateral root number was highly positively correlated with fibrous root mass in the MWNC germplasm source (Table 8).