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Alfred Jones

Sweetpotato [Ipomoea batatas (L.) Lam.] cultivars with high levels of resistance to root damaging insects have been developed through the collaborative efforts of a multidisciplinary research team. These resistances were combined with other traits necessary for a successful cultivar such as: disease resistances; high yield; long storage life; prolific sprout production; marketable root size, shape and skin at tributes; and culinary excellence. Adpotion of quantitative genetic principles, development of a wide gene base, sequential selection schemes, use of effective selection criteria and appropriate susceptible standards contributed to the program's success. These achievements were made with, little prior knowledge about inheritance patterns, gene action, mechanisms of resistance or a complete knowledge of the insects concerned. The value of insect resistant cultivars has become better appreciated with the recent decrease in chemical alternatives.

Free access

Alfred Jones

Sweetpotato [Ipomoea batatas (L.) Lam.] cultivars with high levels of resistance to root damaging insects have been developed through the collaborative efforts of a multidisciplinary research team. These resistances were combined with other traits necessary for a successful cultivar such as: disease resistances; high yield; long storage life; prolific sprout production; marketable root size, shape and skin at tributes; and culinary excellence. Adpotion of quantitative genetic principles, development of a wide gene base, sequential selection schemes, use of effective selection criteria and appropriate susceptible standards contributed to the program's success. These achievements were made with, little prior knowledge about inheritance patterns, gene action, mechanisms of resistance or a complete knowledge of the insects concerned. The value of insect resistant cultivars has become better appreciated with the recent decrease in chemical alternatives.

Open access

Alfred Jones

Abstract

The applicability of the method of correlated responses to selection of sweetpotatoes in a breeding program is illustrated by use of previously determined correlations between 21 traits Examples of the kinds of changes that might be expected due to correlated responses are pointed out. It is further demonstrated that knowledge of such responses can assist plant breeders in making prudent selections and in the design of improved breeding procedures. Agreement of predicted and realized correlated responses indicates that this technique is suited to use with the sweetpotato. Through mass selection procedures, cultivars with most any combination of traits desired should be possible.

Open access

Alfred Jones

Abstract

Heritability (%) estimates of 10 vine characters were obtained from a parent-offspring study of 40 sweetpotato lines as follows: leaf vein purpling, 95; number of buds per cyme, 50; leaf whorl purpling, 74; vine purpling, 53; vine diameter, 111; vine length, 60; internode length, 61; leaf length, 99; plant pubescence, 82; and leaf type, 59. The additive component of variance was more important than the non-additive for all traits. In all cases the realized changes due to selection agreed with the predictions very well.

Open access

Alfred Jones

Abstract

We obtained estimates of genetic components of variance for resistance to Fusarium wilt in sweet-potato, through study of 40 randomly chosen plants of an intermating population and their respective open-pollinated offspring. The additive component accounted for virtually all of the genetic variance. Predicted advance from mass selection of the best 10% of the parents was 10.5% of the mean. The actual advance obtained in offspring of the selected plants was 13.9%. Heritability was estimated as .86.

Open access

Alfred Jones

Abstract

Estimates of phenotypic, genotypic and environmental correlations of 21 sweetpotato traits indicated no serious impediments to selection for improved horticultural types through mass selection techniques. Some secondary traits were genetically correlated with traits of primary economic importance, a factor which suggests that their use in selection indices may be profitable in sweetpotato improvement programs.

Open access

Alfred Jones

Abstract

Twenty-four traits in generations 2 to 7 of a randomly intercrossing sweetpotato [(Ipomoea batatas (L.) Lam.] population were studied. Mean changes detected were: increased flowering, reduced leaf whorl purpling, increased vine purpling, decreased vine diam, decreased root wt, fewer smooth skinned types and some increase in vine length. Changes in the fusarium wilt index were not significant but distributional changes were important; fewer plants with high levels of resistance occurred in the later generation. Reductions in vine diam and in root wt were considered independent of each other. There was no indication that the natural selection for increased flowering was responsible for either vine diam or root wt reductions.

Open access

Alfred Jones

Abstract

Forty-five plants of sweet potato (Ipomoea batatas (L.) Lam.) taken randomly from the second cycle of a mass-selection population, and 25 open-pollinated progeny from each were used to estimate heritabilities (h2) of 7 root traits: root weight, 0.25 ± 0.13; intercellular space (IS), 0.70 ± 0.14; percent of dry matter (DM), 0.65 ± 0.12; sprouting, 0.39 ± 0.14; flesh oxidation, 0.24 ± 0.13; flesh color, 0.53 ± 0.14; and cortex thickness, 0.25 ± 0.13. IS was distributed normally with mean and mode of about 7%. DM had a bimodal distribution with mean 28.8 and modes of 27 and 31%. At least 2 genetic systems were apparently involved in expression of DM; one was associated with orange flesh and the other, with white flesh. This is the first report of the h2 for IS, DM, and sprouting.

Open access

Alfred Jones

Abstract

Awareness that the continuous variation of morphological traits in sweet potato can best be explained and studied with quantitative genetics has increased during the last 20 years (10, 16). This paper has 2 purposes: 1) to summarize available heritability estimates for traits of sweet potato and 2) to alert breeders to their use and application in crop improvement.

Open access

Alfred Jones

Abstract

Mass selection for low oxidation of root flesh was initiated in the fourth generation of an open-pollinated sweetpotato [Ipomoea batatas (L.) Lam.] population. Two selection schemes were followed which provided different selection pressures by varying effective population sizes. In one (population A), selected plants were randomly intercrossed by insects each cycle. In the other (population D), approximately 10% of the randomly intercrossing population were selected each cycle and their true seed used to plant the next generation. After 2 cycles of selection in A and 3 in D, they were compared to appropriate generations of the base population. Results were in agreement with selection theory and closely paralleled those obtained with other crops. More rapid advance was made with A, which requires 2 seasons per cycle for any trait not measured in the seedling stage. Good advance was made with D, which allows 1 cycle per season. Study of 21 other traits indicated more changes in unselected traits in A than in D, thus favoring the method of D in early generations of mass selection in sweetpotato. The rapid increase of low oxidizing plants in this study suggests that selection for low oxidizing cvs. may reduce associated processing problems.