Registration of MSSI Short‐Internode White Clover Germplasm

The original (CO) and mass-selected cycles (Cl to C5) of the composite were evaluated in 1992 at five Iowa locations for yield, root and stalk lodging, plant and ear height, stand, dropped ears, and tassel branch number. Dates of silk emergence and pollen shed were recorded at two locations near Ames. Days from planting to silk emergence decreased 16 d from the CO (94.8 d) to the C5 (78.8 d), a decrease of 3 d per cycle of selection. Correlated changes with selection for earlier silk emergence included decreases in days to tassel (3.4 d cycle") and the interval from pollen-shed to silk emergence (1.8 d cycle""'); plant height (52 cm) and ear height (50 cm) were reduced from the CO to the C5; and grain yield increased 1.5 Mg ha~' from the CO (4.33 Mg ha~') to the C5 (5.82 Mg ha~'). There were no significant changes with selection for stand and root and stalk lodging. Population BS28 has primarily dent kernels that are mostly yellow, but kernel color ranges from white to purple. Plant and ear height of BS28 are 30 to 40 cm less than B84xMol7, and number of days to silk emergence of BS28 is 4 d less than for B84XMol7. Population BS29 was developed from Suwan-l(S)C6 (P1 439741), which was developed in Thailand (3). A sample of Suwan-l(S)C6 was obtained in 1985 and grown in 1986 for seed increase. Mass selection for adaptation to temperate areas was initiated in 1986. Protocols for selection for adaptation and evaluation of response to selection were the same as those described for BS28. Direct and correlated responses with mass selection for earlier flowering in BS29 were similar to those for BS28. Population BS29 tends to be later (= 10 d) and taller (30-40 cm) than BS28. Plant and ear heights of BS29 are similar to B84xMol7, but number of days to silk emergence of BS29 is later (7 to 10 d) than for B84xMol7. The original (CO) population of Suwan-1 was similar to the CO population of the Tuxpeno composite, but BS29 has greater yield than BS28. Kernels of BS29 are flinty and are mostly dark yellow to orange. Plants of BS29 are dark green and vigorous. Populations BS28 and BS29 represent selected strains of germplasm used in tropical breeding programs. Because no temperate germplasm was crossed to the original samples to attain adaptation to temperate environments, BS28 and BS29 include germplasm distinct from the germplasm currently used in U.S. Corn Belt breeding programs. Breeder seed of BS28 and BS29 is maintained by the Iowa Agriculture and Home Economics Experiment Station and is distributed (500 seeds per request) by the Committee for Agricultural Development, 23 Curtiss Hall, Iowa State University, Ames, IA 50011.