ICA Pijao Research Articles

Genetic Control of Abnormal Seedling Development in Phaseolus vulgaris L. and P. vulgaris×P. acutifolius A. Gray Hybrids

AbstractAbnormal hybrid seedling development hinders attempts to introgress diverse germplasm in common bean (Phaseolus vulgaris L.) breeding programs. In this study, the hypothesis that DL1 and DL2 loci control abnormal seedling development both in Phaseolus vulgaris L. intraspecific hybrids and in P. vulgaris×P. acutifolius A. Gray interspecific hybrids was tested. Hybrids from crosses between six P. vulgaris lines (two Andean dl1 d1, DL2DL2, two Mesoamerican DL1DL1 dl2 dl2, and two facilitators dl1dl1, dl2dl2) and P. vulgaris cultivar Ex Rico 23 developed normally, indicating that Ex Rico 23 has the facilitator genotype dl1, dl1, dl2dl2. Previous studies have shown that Ex Rico 23 ×P. acutifolius results in abnormal seedlings, but ‘ICA Pijao’, also dl1, dl1 dl2dl2, ×P. acutifolius results in normal seedlings. Neither the Andean nor the Mesoamerican lines crossed successfully with P. acutifolius, but crosses between one of the two facilitators (G3807) and P. acutifolius resulted in normal seedlings. These results support the hypothesis that different loci control intra‐ and interspecific hybrid seedling development.

SELECTION FOR YIELD AT TWO FERTILIZER LEVELS IN SMALL-SEEDED COMMON BEAN

Selection for seed yield (visual in the F2, visual and plot yield from the F3 to F5, and yield tests in F6) was carried out in two crosses of common bean (Phaseolus vulgaris L.) in high and low soil fertility environments at CIAT-Quilichao, Colombia. Parents were small-seeded and tolerant to low soil phosphorus, possessed indeterminate bush growth habit, and belonged to lowland tropical gene pools of Middle America. The mean yield of selected lines from low (LFS) and high (HFS) soil fertility environments was significantly higher than the mean of the parents in both crosses when tested in high fertility (HF) but not in low fertility (LF). The highest yielding LFS and HFS lines from A 286 × (G 5059 × A 80) and the LFS line from A 286 × ICA Pijao outyielded the best check cultivar, Carioca, in HF. No line yielded significantly more than A 286, the best parent used in both crosses. The mean effect of fertilizer levels on selection for seed yield was nonsignificant. Lines selected under two environments showed similar but average response and high stability of performance under variable environments. Low soil fertility accelerated maturity and reduced 100-seed weight and seed yield.Key words: Phaseolus vulgaris, bean (small-seeded common), selection for yield, soil fertility, Middle American gene pools, regression coefficient

Identification of Common Bean Lines with Ovipositional Resistance to Empoasca kraemeri (Homoptera: Cicadellidae)

Field and greenhouse studies were done to identify ovipositional antixenosis (the plant property responsible for resistance) in common beans, Phaseouts vulgaris L., to the leafhopper Empoasca kraemeri Ross and Moore. The 1985 field study showed considerable variation among 49 resistant bean lines for nymphal counts, damage scores, and yield under leafhopper attack. Bean lines ‘EMP 124,’ ‘EMP 125,’ and ‘EMP 135’ had significantly fewer nymphs per leaf over the growing season than ‘ICA Pijao,’ the tolerant check variety. These results were confirmed in 1986 when nymphal emergence and adult leafhopper counts on ‘EMP 124’ and ‘EMP 135’ were compared with ‘EMP 81,’ another tolerant check. Other bean lines with low nymphal emergence, low damage scores, and high nonprotected yield also were identified. The effect of plant age on antixenosis resistance also was studied under field conditions, and ‘EMP 124’ showed high levels of resistance to leafhopper oviposition as seedlings and plants. Compared with the tolerant check, ‘EMP 89’ and ‘EMP 135,’ however, appeared to be less preferred for oviposition as plants than as seedlings. Greenhouse free choice and no choice studies were conducted on bean seedlings and plants. ‘EMP 124’ and ‘EMP 125’ showed high levels of antixenosis resistance compared with ‘ICA Pijao,’ and ‘EMP 94’ and ‘EMP 135’ were intermediate in their response. Crosses between tolerant and antixenosis bean lines are recommended as a potential means of increasing overall leafhopper resistance levels.

Genetics of Seed Yield and its Components in Common Bean (Phaseolus vulgaris L.) of Middle‐American Origin

AbstractIncrease in yield potential of dry common bean (Phaseolus vulgaris L.) cultivars has been either imperceptible or small and gradual, in spite of large variation of most traits, including seed yield. Therefore, general combining ability (GCA) of 80 cultivars and lines of mostly Middle‐American origin was investigated. Eight sets of 10 entries each were used, with five parents each as females and males in a Design II mating system. The resulting 200 F, populations, excluding parents, were evaluated in a replicates‐in‐sets design for yield and its, components at two locations in Colombia. GCA was, calculated by Griffing's Method 4, Model I.Sixty‐two parents, including high yielding and widely grown small‐seeded Latin American cultivars (‘Aete 3’, ‘Carioca’, ‘Catu’, ‘ICA Pijao’, ‘IPA 74‐19’, ‘Jamapa’, ‘Moruna 80’, ‘Porrillo Sintetico’. ‘Rio Tibagi’), new releases, and many sources of diseases, insect pests, and drought resistance, had zero or negative GCA for yield and its components at both locations. Seventeen out of the 18 parents that had positive GCA for yield at one or both locations were bred lines. At least nine of these resulted from a cross between a small‐seeded cultivar with zero or negative GCA for yield, on one hind, and a landrace from the highlands of Mexico, on the other. Two such landraces, ‘Guanajuato 31’ and ‘Ojo deLiebre’, contributed positive GCA for seed yield and seed weight to all their lines studied, suggesting a major gene control.

Simple Genetic Control of Hybrid Plant Development in Interspecific Crosses between Phaseolus vulgaris L. and P. acutifolius A. Gray

AbstractCrosses were performed between nine Phaseolus vulgaris lines (as females) and seven P. acutifolius lines (as‐ male to examine parental compatibility for the production of vigorous hybrid And backcross plants, in vitro embryo rescue techniques were required to secure hybrid and backcross proseny following interspecific crossing. Seedling development appeared to be dependent on which allele the P. vulgaris parent carried at an interspecific incompatibility locus. Seven of the nine P. vulgaris lines tested carried an allele at this locus which interacted with a nuclear factor in the P. acutifolius genome resulting in stunted, sub‐lethal hybrids. The lines, ICA pijao' and ‘Sacramento Light Red Kidney’ did not carry this allele and produced vigorous hybrid progeny in combination with all P. acutifolius parents. Intensive backcrossing produced progeny which also segregated for sub‐lethal and viable plant development. The observed segregation patterns suggest that a bridge crossing scheme would facilitate the introgression of P. acutifolius germplasm into incompatible P. vulgaris lines. Similarities, with an intraspecific incompatibility system are discussed.