Evaluation of jackbean (Canavalia ensiformis) lines derived from natural crossing with swordbean (Canavalia gladiata)

Jackbean (Canavalia ensiformis (L.) DC.), is considered one of the few pulses that grow really well on the highly leached, nutrient-depleted lowland tropical soils. Natural pollination with its close relative, the swordbean (Canavalia gladiata (Jacq.), offers exploitable opportunities for gene introgression and varietal improvement without the necessities of artificial pollination. This paper reports the growth, biomass yield, nodulation and seed quality of advanced generation lines derived from the natural crossing of jackbean with swordbean. Crop growth rate (CGR) was significantly higher in three selections from the hybrid population than in the jackbean parent, with superiority ratings of 122.7% to 320.5% over the jackbean parent. Superiority in net assimilation rate (NAR) of 53.9% to 215.4%, and in forage yield of 46.5% to 183.6% was also evident in the three selections. However, the leaf weight ratio (LWR), as well as nodule number and nodule biomass were significantly inferior in the three Selections, when compared to the jackbean parent. Seed size remained unaffected in one of the selections (JS 103), but was reduced by 5.6-22.2% in the other two selections. Seed coat fraction was increased by gene introgression from the swordbean, with selections such as JS 102 exhibiting a 50.4% increase.