Grafting as a tool in common bean breeding

Abstract

Compatibility of rootstock for grafting was investigated in four species of Phaseolus to study the use of grafting as a tool in bean breeding programs. Four genotypes of Phaseolus vulgaris and one genotype of P. coccineus were used as rootstocks. Two genotypes of P. vulgaris, and one each of P. acutifolius and P. angustissimus, and an interspecific hybrid of P. acutifolius × P. angustissiumus were used as scions. The common bean genotype ICA Pijao, a widely used female parent in bean interspecific hybridization, was the most compatible rootstock among the five genotypes tested, with high mean percent survival for scions across all four Phaseolus species. Grafting was an efficient technique compared with rooted cuttings for seed increase in determinate type bean plants, where obtaining the maximum number of clones before the reproductive phase is critical. Grafting resulted in 91 and 66% higher mean seed yield per plant compared with ungrafted control and rooted cutting treatments, respectively. This grafting technique using compatible rootstocks such as P. vulgaris ICA Pijao has potential to improve early generation seed increase ratio, multiplication of clones for screening, and perpetuation of sterile or recalcitrant interspecific hybrids for various breeding strategies. Key words: Grafting, Phaseolus sp., interspecific hybrids, compatible rootstocks, clonal propagation, seed multiplication, breeding efficiency