Interspecific hybridization between cultivated soybean, Glycine max and perennial wild species, G. falcata

A total of 461 artificial pollinations were made in the fall of 1979 between plants of G. max (cv. 'Essex' and 'Forrest') and plants of G. falcata (P. I. 246591). Fifty-two F₁ hybrid pods were initiated as a result of these pollinations for a rate of 11.3 percent. This compared to 15.8 percent pod set on manually selfed G. max plants. Twenty-two hydrid pods were allowed to remain on the plant and the remaining 30 pods were removed prior to abortion and cultured in vitro. The maximum size that most pods obtained on the plant was 18 mm. All pods left on the plant aborted within 20 days after pollination except for one pod which remained on the plant 23 days and reached approximately 2 cm. Although 47 percent of F₁ pods exhibited growth of some kind, culturing did not prevent abortion. Three in vitro culture methods utilizing liquid medium were used to determine an optimum method of culturing soybean pods and ovules. Culturing selfed seed from both G. max and G. falcata led to germination when pods were taken from the plant as early as 18 days. Cytological examination of G. falcata root tip cells confirmed a reported chromosome number of 2n=40. Histological examination of cross-pollinated flowers confirmed that fertilization does occur upon cross-pollination and that abortion of ovules and F₁ pods is not due to a lack of fertilization.