Registration of Five Alfalfa Germplasm Pools Glasshouse‐Selected for High Forage Yield and Nitrogen Concentration

Alfalfa (Medicago saliva L.) germplasm pools UCNP-A32 (Reg. no. GP-295, P1 591458), UCNP-HP32 (Reg. no. GP-296, P1 591459), UCNP-M69-32 (Reg. no. GP-297, P1 591460), UCNPM69 (N2+NO3)2 (Reg. no. GP-298, P1 591461), and UCNP-M6933 (Reg. no. GP-299, P1 591462) were released by the Department of Agronomy and Range Science and the California Agricultural Experiment Station in May 1992. UCNP-A32 (Univ. of Calif. [UC] id no. UC-1377) and UCNPHP32 (UC id no. UC-1380) are honey bee (Apis mellifera L.) pollinated Cycle-2 Syn-2 populations developed from 'African' and 'Hairy Peruvian', respectively, by two cycles of phenotypic recurrent selection conducted in the glasshouse (1). Independent culling levels were used to screen for forage dry weight production followed by forage N concentration under both N^ and NFLtNOs— dependent growth conditions. Cycle 1 was developed by intercrossing seven plants selected for high forage dry weight and N concentration from a sample of 125 plants from each parental source. Plants (n = 150) from each Cycle-1 population were subsequently screened for the same traits, and seven and nine plants were selected and intercrossed to produce UCNP-A32 and UCNPHP32, respectively (6). UCNP-A32 and UCNP-HP32 were evaluated in the glasshouse under both N^ and NH4NC>3-dependent growth conditions corresponding to those used during selection. Forage N concentration in both germplasm pools averaged 5.2% greater than in their respective parental sources (6). Dry matter production of UCNP-A32 and UCNP-HP32 averaged 17 and 52% greater than African and Hairy Peruvian, respectively. UCNP-A32 showed significant improvement in total in vitro digestible dry matter (TIVDDM) of stems only under NH4NO3-dependent conditions (2). The improvement in digestibility was associated with significant reductions in neutraland acid-detergent fiber and cellulose. In contrast, whole-plant TIVDDM of UCNP-HP32 was significantly (P < 0.05) greater than for Hairy Peruvian with both N sources. In UCNP-HP32, the major improvement in TIVDDM was largely the result of increased forage yield, although leaves from UCNP-HP32 also showed a significant increase in N concentration and a reduction in neutraldetergent fiber and lignin. Tests during early seedling development under glasshouse conditions showed that UCNP-HP32 had a significantly greater number of root nodules and a higher rate of apparent N2 fixation (acetylene reduction activity/plant) than Hairy Peruvian (3). Under controlled environment conditions, N2 fixation of UCNP-HP32 was greater than N concentration of Hairy Peruvian across a range of solution N concentrations. This germplasm also promotes greater N2 fixation from individual Rhizobium meliloti strains differing widely in N2 fixation capacity (4). UCNP-M69-32 (UC id no. UC-1429), UCNP-M69(N2+NO3)2 (UC id no. UC-1459), and UCNP-M69-33 (UC id no. UC-1530), are honey bee-pollinated Cycle-2 Syn-1 populations selected from 'Moapa 69' following the glasshouse selection protocol (4,5). These three populations were all developed by phenotypic recurrent selection using the same selection intensity (10%), but they differ in population size. UCNP-M69-32 was developed by two cycles of selection, with 125 plants selected for high forage dry weight and N concentration intercrossed in each cycle. UCNP-M69(N2+NO3)2 was developed by two cycles of selection in which the best 25 plants were selected and intercrossed. UCNP-M69-33 was developed from UCNP-M69-32 by one additional cycle of selection in which 10 plants selected for high forage dry weight and N concentration were intercrossed. During the selection process, all pollinations were made by hand without emasculation. Glasshouse evaluation of UCNP-M69-32, UCNP-M69(N2+ NC>3)2 and UCNP-M69-33 for forage N concentration and dry weight showed significant selection responses (7). Both UCNPM69-32 and UCNP-M69(N2+NC>3)2 produced more (P < 0.10) forage dry weight, but no improvement in forage N concentration could be demonstrated. UCNP-M69-33 exhibited significant (P < 0.001) improvement in both forage dry weight (154% of Moapa 69) and forage N concentration (109% of Moapa 69) averaged across both N^ and NfyNC^-dependent growth conditions. During the first production year at Davis, CA, UCNP-M69-33 contained significantly more forage N and derived a greater fraction of forage N from N2 than Moapa 69 (5). Forage N derived from N2 was estimated both by N dilution and by N difference methods using an ineffectively modulated alfalfa population, MN IN-Sar, as a baseline control. Results from field tests averaged across 2 yr and four California locations showed that forage yield was 2.1 and 6.5% less (P < 0.05) for UCNP-M69-32 and UCNP-M69-33, respectively, than for Moapa 69 (8). Forage quality, however, was improved by selection: forageN concentration of both UCNP-M69-32 and UCNP-M69-33, and both acidand neutral-detergent fiber of UCNP-M69-33, were improved significantly (P < 0.05) over Moapa 69 (8). Seed of UCNP-A32 (1.0 g), UCNP-HP3, (0.5 g), UCNP-M6932 (1.0 g), UCNP-M69(N2+NO3)2 (5.0 g), and UCNP-M69-33 (5.0 g) will be distributed upon written request and agreement to make appropriate recognition of its source a matter of open record when the germplasm contributes to the development of either a publication or the development of a cultivar, hybrid, or germplasm. Request seed from the corresponding author. Seed requests should specify the UC identification number (given above) as well as the registered name and P1 number. Requests from outside the USA should be accompanied by appropriate customs control documents.