Developing Perennial Upland Rice II: Field Performance of S1 Families from an Intermated Oryza sativa/O. longistaminata Population

In Southeast Asia, upland rice ( Oryza sativa L.) is an annual crop that is typically cultivated on hilly sites, contributing to the erosion of soil and the degradation of watersheds. We wish to develop a perennial upland rice that would help conserve natural resources via a permanent ground cover, while providing subsistence farmers with a valued food. Oryza longistaminata A. Chev. et Roehr. is a highly perennial, rhizomatous relative of O. sativa that may be a useful source of genes for developing perennial upland rice. This study was conducted to evaluate the potential of an O. sativa/O. longistaminata intermated population for developing perennial upland rice. As a baseline for comparison, none of the cultivar controls survived 1 yr. Among 94 S 1 families, 1‐yr survival ranged from 0 to 63.6% but only six families had more than 30% survival. On the basis of observations at the soil surface, less than 1% of the progeny plants produced rhizomes. However, three families produced approximately 25% rhizomatous individuals, suggesting the presence of a single locus with large effect. Interspecific crossing barriers led to low S 1 yields, with many plants being completely sterile. The low fertility and limited perenniality observed may make further breeding progress with this population difficult.