Table 3. Seed yield traits for the F 2:7 RILs. TWO THUMBS UP FOR YIELD TRAIT VARIATION IN WHITE LUPIN S.L. Noffsinger and Edzard van Santen Department of Agronomy and Soils, 202 Funchess Hall, Auburn University, AL ABSTRACT A 'Tifwhite-78' derived line (indeterminate, low alkaloid, white flowers, small seed size) was crossed with 'Lucyanne' (determinate, low alkaloid, white flowers, large seed size). From a single F1 seed, 208 F 2:7 recombinant inbred lines (RILs) were developed by single seed descent (SSD) in the greenhouse, and 6 plants per F 2:7 RIL were hand- sown on October 25, 2002 at E.V. Smith Research Center in central Alabama, USA. Due to insect destruction of the mainstem in many lines that winter, the basal mainstem and branches developed at the same time and functioned like mainstems and branches. The growth habit range was very diverse (Fig. 1, 2), and 13 RILs were segregating for determinate vs. indeterminate growth in the F 2:7 and F 8. Growth habit variation better fit a 9:7 ratio with a two or more gene model; this also indicates that within a single cross, one could select out a broad range of growth habit types if needed. Mean seed weight and pod wall proportion, as well as yield trait variation with regard to growth habit classes will be discussed. The variation in agronomic traits should provide a good basis for beginning both genetic and yield studies. OBJECTIVE Examine agronomic traits in segregating RILs of winter-type white lupin. INTRODUCTION In any breeding program, genetic variation is necessary for progress in selection and to obtain genotypes which fit either the environment and/or the particular crop use. In the case of winter-type white lupin (Lupinus albus L.), multiple potential uses for this crop require selection for traits which meet the use of a particular variety, e.g. more severe determinate growth for a variety with uniform seed size for snacks and other types of human consumption vs. indeterminate growth with rapid regrowth for a deer forage variety (Noffsinger et al., 2006a). In this study, we examined 208 F 2:7 RILs obtained from a single F 1 seed for segregating agronomic traits. MATERIALS AND METHODS Original Cross ‘Tifwhite-78’ x ‘Lucyanne’ indeterminate determinate low alkaloid high alkaloid white flowers white flowers small to ave seed size large seed size EV Smith Research Ctr (Central AL) 208 F 2:7 RILs* 6 seeds hand-sown, 1 replicate Sown October 25, EV Smith Research Ctr (Central AL) 13 segregating RILs sown plant to plot 189 non-segregating RILs bulked for mainstem seed and hand-sown as F 8 Also planted: ‘AU-Homer’ (cover crop, indeterminate) Deer_305 (indeterminate) Deer_310 (indeterminate) ‘Lucyanne’ XA100 (dwarf) 10 seeds/plot, 2 replicates Sown October 29, 2003 *In the greenhouse, F 2:7 RILs were produced by SSD without the presence of pollinating insects. CONCLUSIONS Segregation for growth habit in 13 of the 208 F 2:7 RILs and segregation in the following F 8 lines (data not shown) indicates that one could obtain a better test for grain yield differences among growth habit types with segregating sister lines. In the past, scientists have used distantly related cultivars which had growth habit differences to examine grain yield differences. The variation in agronomic traits should provide a good basis for beginning both genetic and yield studies, and future breeding. RESULTS The majority of the F 2:7 RILS had mainstem damage caused by lupin fly (Hylemia lupini L.) on at least 1 or 2 plants, if not the entire 6 plants. Spraying the F 8 with insecticides throughout the winter of seemed to eliminate the lupin fly problem, and resulted in a dramatic decrease in damaged mainstems. Growth habit variation was beyond that predicted by previous assumptions of a 3:1 ratio (Fig. 1, Table 1 ; Noffsinger et al., 2006b), indicating not only that more than one locus is responsible for the growth habit trait, but also that one could obtain a continuous range of variation for growth habit if needed from a single cross. The stability of growth habit ratings in the 2 to 3.5 range was least stable from the F 2:7 to F 8 generations (Noffsinger et al., 2006b) although some individual RILs were stable in that range (data not shown). The regression of growth habit type on main-stem chlorophyll meter readings (LSMEANS) for the F 2:7 RILS provided a quadratic equation (y = x – 0.36x 2 ; R 2 = 0.96) indicating pleiotrophic effects of growth habit, causing epigonal and severely determinate types to be darker in leaf color/chlorophyll content (Noffsinger et al., 2006b). The range of values shown in Fig. 3 indicates that one could possibly select for higher chlorophyll content within growth habit types, if this were found to be tied to a useful trait such as water use efficiency, which has been found in corn and peanut. Height to first mainstem pod was 5 to 107 cm and height to first basal mainstem pod was 2 to 120 cm in the F 2:7 (data not shown). Some of this was growth habit related but, there was still considerable variation within growth habit types and even within some RILs, indicating opportunities for selection. In Table 3, pod wall proportion was less for epigonal types (1), which should be expected given the early abortion of most unfilled pods. The low seed weight values indicate inheritance from Tifwhite-78. REFERENCES Noffsinger, S.L., H.L. Bhardwaj, and E. van Santen. 2006a. An ideotype for winter-type grain white lupin in the southeastern USA. p In E. van Santen and G.D. Hill (eds.) Proceedings of the 11 th International Lupin Conference, Guadalajara, Jalisco, Mexico. May 4-5, International Lupin Association, Canterbury, New Zealand. Noffsinger, S.L., H.L. Bhardwaj, and E. van Santen. 2006b. Cherish your exceptions: some unusual phenotypes in an F8 indeterminate x determinate RIL population. p In E. van Santen and G.D. Hill (eds.) Proceedings of the 11th International Lupin Conference, Guadalajara, Jalisco, Mexico. May 4-5, International Lupin Association, Canterbury, New Zealand. Fig. 1. Agronomic trait variation in winter-type white lupin: (A) earlier and later mainstem flowering, (B) a severe epigonal type, and (C) segregation for determinate vs. indeterminate growth in a F 2:7 RIL. (A) (B)(C) Fig. 2. The full range of determinate through indeterminate growth habit was displayed in the F 2:7 and F 8 RIL populations. The female parent, Tifwhite-78, was a traditional indeterminate type (7-7.5), and the male parent, Lucyanne, was a traditional determinate type (4-4.5). 1 to 1.5 = Epigonal 2 to 2.5 = Semi-epigonal 3 to 3.5 = Epigonal determinate 4 to 4.5 = Determinate 5 to 5.5 = Semi-determinate 6 to 6.5 = Semi-indeterminate 7 to 7.5 = Indeterminate 8+ = Highly Indeterminate Fig. 3. Growth habit type vs. SPAD meter readings for the mainstem of 208 F 2:7 RILs, April 20, The mainstem was killed by the lupin fly (Hylemia lupini L.) so basal mainstem growth developed at the same time as the mainstems and was treated as mainstems for the SPAD readings. Growth habit type (scale 1-8) SPAD meter reading Table 1. Segregation for growth habit in 13 F 2:7 RILs. RILs 1056, 1115, and 1142 had more subtle segregation in the 6-8 range for the F 8, and would require further generation advance to verify growth habit segregation. Table 2. Chi-square ratios for the growth habit types of F 2:7 RILs.