Path Coefficient Analysis among Components of Yield in Bambara Groundnut (Vigna subterraneaL,. Verde) Landraces under Screen House Conditions

摘要

A screen house experiment was conducted at the Sokoine University of Agriculture, Morogoro Tanzania, to discern the relationships among components of yield in Bambara groundnut V. subterranea genotypes using path coefficient analysis. The trial was conducted during January-May, 2000. Nine genotypes of Bambara groundnut landraces were laid out in a Completely Randomized Design with four replications. Results showed that leaf length was the only vegetative variable which had a significant and positivecorrelation (r = 0.50*) with yield. Path coefficient analysis shows that this correlation was mainly attributed to the independent (direct) contribution (0.393) of leaf length on yield though the latter was far less than its respective residual effect. Number of pods per plant were highly correlated (r = 0.83**) with seed yield and the direct effect on yield (0.998) was relatively higher than the residual. On the other hand, the number of days to flowering were negatively correlated with yield (r = -0.41*) and this correlation was predominantly attributed to its negative direct effect (-0.461). The latter was also higher than its respective residual effect. Petiole length was negatively correlated with 100 seed weight (r = -0.41 *) and this was largelydue to its negative direct effect (-0.310) on seed size. This direct effect was, however, far less than its residual effect. Plant height and leaf length were both positively correlated with number of pods produced. Their correlations were largely due to their direct effects on number of pods per plant although these direct effects were less than their respective residual effects. Although 100 seed weight had a non significant correlation with seed yield (r = 0.16), its independent effect (0.541) on yield was higher than the residual effect of 0.299. However, the indirect effect of seed size on yield through number of pods (-0.381) reduced the direct effect to a low and non significant correlation with yield. The present study shows that number of pods interacted negatively with 100 seed weight in influencing yield of Bambara groundnut. Taller plants, longer leaves and more podding are variables which are related to higher yields of Bambara groundnut under screen house conditions.