Inbreeding Effects for Selected Agronomic Characters in Eastern Gamagrass

Abstract

Information on the consequences of inbreeding in naturally crosspollinated plants is useful in determining strategies for genetic manipulation. Research was conducted in 1982 and 1983 to determine the effects of inbreeding in eastern gamagrass [Tripsacum dactyloides (L.) L.) on plant height (PH), plant weight (PW), 100‐spikelet weight (SW), and fertility measured by the percent of spikelets containing pure live seed (PLS). Plant materials consisted of 20 randomly chosen parents from a diploid (2n = 2x = 36) panmictic population and S1 and S2 progeny derivatives. Twenty ramets of each parent, 822 S1 seedlings, and 593 S2 seedlings were field grown using a completely randomized design. Parental plants had higher mean PH, PW, and SW than S1 or S2 progeny populations (P < 0.01). No consistent differences for these traits were detected between the S1 and S2 generations. More than two‐thirds of the parents had significantly higher PH and PW than their S, or S2 progenies. In 1982. SW did not differ between generations; in 1983, however, 80% of the parents had significantly greater SW than their respective S1 or S2 generation progenies. Inbreeding had little detrimental effect on PLS. Less than one‐half of the parents had a greater percentage of spikelets containing PLS than their corresponding S1 and S2 generation progenies in 1982, and even fewer differences were found in 1983. Plants with reduced vigor but normal color, yellow and albino plants, and plants with altered floral morphology were found in selfed progeny populations. Inbreeding eastern gamagrass should have value in exposing recessive alleles existing at low frequencies and in the development of inbred lines.