Jeffrey W. White

Root growth of four common bean cultivars in relation to drought tolerance in environments with contrasting soil types

Root growth of two drought tolerant and two drought sensitive bean (Phaseolus vulgaris L.) lines was compared at two locations in Colombia differing primarily in soil conditions. At Palmira, roots of drought tolerant lines reached a depth of 1.3 m, while drought sensitive lines only reached 0.8 m. These differences were associated with differences in seed yield, crop growth, canopy temperature and soil moisture extraction. Under acid soil conditions at Quili-chao, seed yields of supposedly drought tolerant genotypes were similar to those of the drought sensitive lines, and root growth of all four lines was restricted to less than 0.8 m. Drought avoidance through greater root growth and extraction of soil moisture appears to be an important drought tolerance mechanism in common beans, but its usefulness is limited where soil conditions restrict root growth Root Growth of Four Common Bean Cultivars in Relation to Drought Tolerance in Environments with Contrasting Soil Types | Request PDF. Available from: https://www.researchgate.net/publication/231907323_Root_Growth_of_Four_Common_Bean_Cultivars_in_Relation_to_Drought_Tolerance_in_Environments_with_Contrasting_Soil_Types [accessed Sep 13 2018].

Characterization of the negative association between seed yield and seed size among genotypes of common bean.

Contrary to expectations from arguments of exponential growth or limiting factors, seed yield and seed size of different bush-bean (Phaseolus vulgaris L.) genotypes are frequently negatively associated. Four sets of yield data are analyzed to characterize this apparent seed size limit to yield potential. Comparisons of 57 genotypes, classified as small-seeded vs. medium-to-large-seeded and grown in three trials at two locations in Columbia, gave mean yields of 2190 and 1740 kg ha−1 for the respective seed-size classes, corresponding to a 280 kg ha−1 reduction in yield per 100 mg increase in cultivar seed weight. Published data for a trial conducted at five sites with 190 genotypes, for 19 experiments of an international yield trial, and for 42 nurseries conducted in Michigan, confirmed this relation, but also showed that positive relations between seed size and yield occur in certain environments. Including effects of length of growth-cycle did not eliminate overall negative relationships. Possible causes of the seed-size effect include effects of characteristics correlated with seed size that in turn affect efficiency of certain physiological processes, or differences in adaptation resulting from limited gene exchange among gene pools differing in characteristic seed size. To examine the possibility of a physiological cause related to developmental correlations between seed size and tissue cell volumes, seed weight and approximate cell volumes of cotyledons, hypocotyl and root endodermis, guard cells, and palisade mesophyll, and volumes of pollen grains, were determined for 15 genotypes, including two wild accessions. All volume measurement had positive correlations with seed weight except for palisade mesophyll. Principal-components analysis of cell volumes defined a first component accounting for 51% of total variance, and which had a correlation of r = − 0.91 (P < 0.01) with seed weight. Further comparison of seed weightand pollen grain volume in 33 genotypes gave a correlation of r = 0.67 (P < 0.01).

Inheritance of seed yield, maturity and seed weight of common bean (Phaseolus vulgaris) under semi-arid rainfed conditions

To develop an effective breeding programme for rainfed production of the common bean ( Phaseolus vulgaris L.), the inheritance of seed yield under such conditions should be understood, preferably considering the effects of environment to account for site or season specificity. Thus, heritability, expected and realized gain from selection, and combining ability were evaluated for a nine-parent diallel of common bean without reciprocals but including parents, at two locations each in Mexico and Colombia, using the F 2 and F 3 population bulks. Heritability estimated from regressions of F 3 on F 2 ranged from 0·09 ± 0·18 (S.E.) to 0·75±0·25 for seed yield, from 0·26±009 to 0·34±009 for days to maturity and from0·57±004 to 0·80±004 for 100-seed weight. Expected gain from selection in the F 2 was estimated as a percentage of the population mean, selecting the upper 20% of the populations. Expected gain in seed yield ranged from 1·8 to 8·4% in Mexico and from 6·5 to 28·1% in Colombia. Realized gains in seed yield in the F 3 were 0·4–7·4% in Mexico and 2·9–15·7% in Colombia. Realized gain values for days to maturity were 13·4%. General combining ability (GCA) mean squares (estimated using Griffings Method 2, Model 1) were significant ( P

Growth habit and gene pool effects on inheritance of yield in common bean

SummaryTo satisfy farmer and consumer preferences, breeding efforts to increase yield potential in common bean must take into account the interrelated effects of growth habit, seed size, maturity, and gene pool on yield expression in segregating populations. To examine the relationships among these traits, a genetic study was conducted to determine the effect of growth habit on yield and seed size in crosses among five bean lines from diverse gene pools. Two parental bean lines had determinate, type I growth habits and large seed size typical of the Neuva Granada-Andean gene pool. Two other lines were tropical Mesoamerican types with type II growth habits and small seed size; and the fifth line, G13625, a landrace of the Jalisco gene pool from the Mexican highlands, had a type IV climbing growth habit and medium seed size. Individual F2 plants from each cross and parental lines were evaluated for growth habit and yield component traits under high input field conditions. The following season, the evaluations were repeated on random F3 plants. Of the five parental lines, only G13625 showed significant GCA effects for yield in both the F2 and F3 generations. Improved yielding ability of G13625 progeny was associated with an increased expression of climbing bean growth habit traits: guide length, climbing ability, node number on main stem, and plant height. Crosses between Andean x Mesoamerican and Andean x Jalisco genotypes, as well between growth habit type I (Andean x Andean) and between type II (Mesoamerican x Mesoamerican) had very low parent-offspring heritability values for yield. Yield heritability was only significant for crosses between Mesomerican x Jalisco gene pools. An apparent simple genetic control of growth habit modification towards semi-climbing and climbing types is proposed as the major reason for increased yields in these crosses. No genetic linkage between genes controlling growth habit and seed size was detected which might restrict the development of high yielding large-seeded type II lines.

Photoperiod response of flowering in diverse genotypes of common bean (Phaseolus vulgaris)

Abstract Adaptation of common bean is strongly affected by photoperiod, and there is considerable genetic variation for photoperiod response in the species. In order to characterize this variation, over 4000 bean genotypes have been screened at the International Center for Tropical Agriculture (CIAT). Response was measured by delay in flowering under artificially extended 18-h daylengths vs. approximately 12.5-h natural daylengths. Approximately 60% of genotypes were found to be photoperiod-sensitive. Small-seeded and bush-indeterminate materials had the highest proportion of day-neutral genotypes. Germplasm accessions from higher latitudes were predominantly day-neutral, while those from lower latitudes demonstrated responses dependent upon apparent regional differences in altitude of adaptation and in seed-type classes. Recently bred cultivars from Latin America showed variation in response similar to traditional germplasm. A frequency distribution of photoperiod response in 3060 genotypes showed three distinct peaks, suggesting simple genetic control.

Effects of seed size and photoperiod response on crop growth and yield of common bean

Seed size and yield are usually negatively associated among common bean (Phaseolus vulgaris L.) cultivars of bush growth habit. Furthermore, among cultivars varying in photoperiod response for flowering, yields are often lower in photoperiod-sensitive genotypes. While the seed-size effect might extend to overall crop growth, photoperiod response would be expected primarily to influence phenology and, possibly, partitioning. To examine these hypothesized effects, yield, crop dry weight at two stages, harvest index (hi), and day to maturity were evaluated for 62 genotypes grown at three sites in Colombia and at Davis, California. Regression analyses indicated highly significant negative relationships between seed weight and all variables except days to maturity, even when significant photoperiod effects were accounted for or when analyses were restricted to genotypes from highland environments. Greater sensitivity to photoperiod was associated with lower yields and hi, and delayed maturity, at Davis, and there was a similar, but much weaker, trend of lower yield and hi in the other environments. Because large seed size was associated with reduced growth, relative growth rate (rgr) of 16 bean genotypes was measured at two of the Colombian sites. At both sites, rgr was negatively correlated with seed weight (R2 = 0.59 and R2 = 0.44, P < 0.01). These results suggest that greater seed size is associated not only with reduced yield, but also with reduced overall growth, and that the effect is largely independent of photoperiod sensitivity, even though the latter influenced phenology and partitioning.

Sources and inheritance of earliness in tropically adapted indeterminate common bean

SummaryNineteen early maturing, indeterminate common bean parents were crossed with a tester line of normal maturity. All parents, F1 hybrids, F2s, and backcross generations were evaluated at CIAT-Palmira, Colombia. All 19F1 populations flowered and matured almost as early as the respective early parent (mean of 61 vs 59 days). The F2 populations were slightly less early (63 days), but were still earlier than the mean of the two parents (65 days). Additive effects for days to maturity were usually larger than dominance or interaction effects. Narrow sense heritability for days to flower and maturity were high (greater than 0.67), while heritabilities of absolute and relative duration of pod filling were low (0.17 to 0.50). Also, our data indicated that for each day of increase in earliness, yield potential will decrease 74 kg/ha.

Relations of carbon isotope discrimination and other physiological traits to yield in common bean (Phaseolus vulgaris) under rainfed conditions

Although direct selection for seed yield under water deficit can result in genetic gains in the common bean ( Phaseolus vulgaris L.), progress could be enhanced through selection for additional traits that are related to underlying mechanisms of adaptation to water deficit. Carbon isotope discrimination (Δ) has received considerable attention as an indicator of water use efficiency and adaptation to water deficit. To test the utility of Δ as a selection criterion, Δ and other traits were measured in F 2 and F 3 generations of a nine-parent diallel grown under rainfed conditions at two locations in Colombia with contrasting soil types. An irrigated trial was also conducted at one location. Significant ( P 0·05) differences among parents, F 2 and F 3 were found for carbon isotope discrimination (Δ), leaf optical density (OD), leaf nitrogen (N) and potassium (K) concentrations, relative duration of pod-filling period (RDPF), shoot dry weight (SDW) and harvest index (HI). Effect of location and water regime and their interactions with genotype were also frequently significant. Heritability estimates, determined by regressing the F 3 on the F 2 , ranged from 0·11±011 (S.E.) to 0·33 ±0·10 for OD, 0·22 ± 0·07 to 0·44±0·09 for N, 0·04±0·05 to 0·29±0·08 for K, 0·40 ± 0·08 to 0·43 ± 0·15 for RDPF and 0·30±0·22 to 1·00±0·24 for SDW. All values for Δ and HI did not differ significantly from zero. Correlations between seed yield and OD and RDPF were negative, whereas those with N, K, SDW, and HI were positive. For all traits, mean square values for general combining ability (GCA) were usuall significant and larger than those for specific combining ability (SCA). All significant GCA effects for Δ for ‘Rio Tibagi’, ‘San Cristobal 83’ and ‘Apetito’ were negative, while those for ‘Bayo Rio Grande’, ‘Bayo Criollo del Llano’, ‘Durango 222’ and BAT1224 were positive. Although Δappears unsuitable as an indirect criterion for selection for yield under water deficit, further study of genotypes exhibiting contrasting values of A might reveal differences in mechanisms of adaptation to water deficits, thus leading to other selection criteria or identification of valuable parental lines.

Effect of growth habit on yield of large-seeded bush cultivars of common bean

Abstract Among common bean cultivars ( Phaseolus vulgaris L.) with bush growth habits, large-seeded cultivars usually give lower yields than small-seeded ones, especially in warm, tropical environments. One suggested cause of this yield difference is that the determinate stem type typical of large-seeded bush cultivars is somehow less efficient than the indeterminate habits usually associated with small-seeded cultivars. To evaluate this hypothesis, yields of five pairs of large-seeded near-isogenic lines of contrasting growth habits were compared over five trials at three sites in Colombia. To obtain evidence from a group of materials with a broader genetic background, an additional 19 indeterminate and five determinate medium- to large-seeded experimental lines were grown in five trials at the three sites. In comparisons of the near-isogenic lines, no effect of growth habit on yield was detected in any of the trials. Determinate growth habit, on the average, resulted in 4 days earlier maturity. For the evaluation of 24 lines, the mean yield of the determinate lines over the five locations was 1700 kg ha −1 , significantly lower than the mean yield of 1890 kg ha −1 for the indeterminates. Determinates matured 5 days earlier than indeterminates. Stability analyses for both studies indicated greater variation in yield stability of indeterminete lines as compared to the determinates. In the 24-genotype study, several indeterminate lines combined both high and stable yields. While the results of the near-isogenic lines indicate that differences in growth habit are not sufficient to explain low yields in large-seeded cultivars, the comparison among 24 lines suggests that the genotypic variation present within indeterminate growth habits may offer greater potential for yield improvement of large-seeded bush types without loss of yield stability.

Inheritance of temperature sensitivity of the photoperiod response in common bean (Phaseolus vulgaris L.)

SummaryPhotoperiod response of flowering in common bean (Phaseolus vulgaris L.) is thought to be controlled by the genes Ppd and Hr. However, cultivars also vary in the degree that cooler temperatures reduces their sensitivity to photoperiod. To examine the inheritance of this temperature sensitivity, crosses of cvs. Gordo x de Celaya and Flor de Mayo × Rojo 70 were evaluated at two sites differing in mean temperature and using 12.5-h natural photoperiod or 18-h artificially extended photoperiod. Under 18-h photoperiod at the warmer site, Palmira, no plants of the parents or of the F2 populations flowered, confirming that the parents were sensitive to photoperiod. Under 12.5-h photoperiod at the cooler site, Popayan, the parents for each cross flowered at similar dates and no segregation for days to flower was observed. However, under 18-h photoperiod, de Celaya and Rojo 70 and the F1 populations did not flower within 100 days after planting, while the F2 and F3 populations showed segregation that was consistent with single gene inheritance, late flowering being dominant. Late flowering at Popayan under 18-h photoperiod indicates a lack of temperature sensitivity, so temperature insensitivity of the photoperiod response was dominant to sensitivity. The name Tip, for “temperature insensitivity of photoperiod response”, is proposed for this gene, with the recessive form of this gene conditioning earlier flowering at cooler temperatures with long daylengths. It is recognized that the observed segregation patterns could represent the effect of multiple alleles at the Ppd or Hr loci, and studies are proposed to test this possibility with molecular markers and recombinant inbred lines.