Comparative Phenemics of Root Traits in Phaseolus vulgaris and Wild Phaseolus Species.

Crop wild relatives (CWR) are wild plant species sharing relatively recent common ancestry with cultivated plants (Harlan and de Wet, 1971). CWR typically possess wide diversity, much of it hasn't founded in the crop, and this diversity may be introgressed into the crop by plant breeders, with the ease of transfer of genes generally dependent on the degree of relatedness between the wild species and the domesticate (Singh, 2001). In addition, Nielson et al., 2001) concluded that root hairs can contribute up to 67 % of  the capacity of plants to absorb both water and mineral nutrients from the soil. In this study we compare the root traits in Phaseolus vulgaris and wild Phaseolus species. This experiment was done under greenhouse condition and roll ups. Fifty two lines of Phaseolus species, cultivated and wild, were evaluated in relation to basal root whorl number (BRWN), basal root number (BRN) and root hair density/length (RHD/L).  The following study allows for selecting genotypic differences in high basal root whorl number, basal root number and high root hair density and length among the Phaseolus species under greenhouse and roll ups.  Wild bean accessions tended to have a BRWN of one or two, whereas cultivated accessions had BRWN reaching four and sometimes five. Greater BRWN was beneficial for phosphorus acquisition in low phosphorus soil. Lines with three whorls had almost twice the shoot biomass, greater root length and greater leaf area than related lines with two and one whorls. The RHD and RHL are very important for the phosphorous uptake from the soil by explaining the absorptive surface area of root and increasing the soil volume explored by roots. Our results indicated highly root hair density and length in the wild beans than in the cultivated.