Sweetpotato Grown from Root Pieces Displays a Significant Genotype × Environment Interaction and Yield Instability

Various workers have attempted to develop a root piece planting system for sweetpotato, similar to the system used commercially for potato, but attempts to select and breed sweetpotato clones adapted to root piece planting have met with mixed success. It has been hypothesized this is the result of significant genotype × environment effects, which are complicating phenotype screening. The aim of this work was to investigate genotype × environment interactions and yield stability of sweetpotato grown from cut root pieces. Ten sweetpotato clones were grown from cut root pieces in three locations over three seasons at sites in North Carolina and Mississippi. The study found sweetpotato clones grown from root pieces were influenced by both genetic and environmental factors and that the interaction was often complicated and dependent on the trait being measured. A significant genotype × environment interaction and yield instability were found to be present. Further work will be required to understand the nature of the genotype × environment effects; however, the results suggest programs aiming to develop sweetpotato clones adapted to root piece planting will need to use appropriate multienvironment screening so as to account for genotype × environment effects.

Root Piece Planting in Sweetpotato—A Synthesis of Previous Research and Directions for the Future

Sweetpotato (Ipomoea batatas) is traditionally grown for fresh consumption, particularly in developed nations, but it is increasingly being used for alternative markets such as processed foods and industrial products. Sweetpotato is well suited for these end uses but its utilization is limited due to high production costs. These costs are primarily the result of high labor inputs. As a vegetatively propagated crop, sweetpotato is typically planted using unrooted plant cuttings, or “slips,” which requires hand labor at several stages. Consequently, planting costs can be as high as 20% of total production costs. As an alternative to slips, sweetpotato can be established using root pieces, similar to the seed piece system used for potato (Solanum tuberosum). This system can be readily mechanized and therefore has the potential to reduce labor demands. Root piece planting has been investigated several times since the 1940s but is not reported to be in large-scale commercial use anywhere in the world. In this work, we review the research literature relating to root piece planting in sweetpotato. This literature demonstrates that it is possible for sweetpotato root pieces to produce yields comparable to slips, but that in most cases yields from root pieces are usually lower than from slips. We conclude that given suitable cultural management and appropriate varieties, it may be possible to successfully produce sweetpotato using root pieces. More work is necessary to develop root piece planting as a viable alternative to slips in sweetpotato production. This work should include the selection and breeding of adapted varieties, evaluation of the economics of sweetpotato production using root pieces, development of planting equipment suited to sweetpotato root pieces, and examination of chemical treatments to improve success of root piece planting.

Chronic Odontogenic Sinus Tracts associated with an Impacted Tooth: Report of Two Cases

ABSTRACT Odontogenic sinus tracts in the face and neck region are relatively uncommon and may present a diagnostic problem. As specific dental symptoms usually are absent in these cases, patients generally visit physician first for the evaluation and treatment because of the absence of dental symptoms. These cutaneous sinus tracts are most commonly located on the chin, cheek or in the submandibular area and rarely in the nasal region. Diagnostic errors can result in multiple surgical excisions and biopsies, long-term antibiotic therapy and even radiation therapy or electrodessication.1 The primary odontogenic disorder that results in such cutaneous lesions is typically a chronic periapical abscess or an impacted tooth or a root piece. We report two cases of extraoral sinus tracts, which were diagnosed as cutaneous sinus tracts of dental origin only after the failure of initial misdirected therapy.

Seed dispersal and seedling establishment of Linaria vulgaris Mill.

The importance of seeds to the establishment and spread of Linaria vulgaris infestations in Alberta was assessed in 1988 and 1989. Stands were established on 17 May 1988. One 10-cm-long root piece with a 10-cm-tall shoot was planted in the centre of each of nine plots on fallow land and of nine plots in a barley crop. Over 90% of seeds in 1988, and over 80% in 1989 fell within a 0.5-m radius of the parent plants with very few seeds falling outside a 1.5-m radius. Seed deposition vs. distance followed a negative polynomial function. It was estimated that over 210 000 seeds m−2 fell less than 0.5 m away from the parent plant over the 1988 growing season. The presence of Gymnaetron sp. and Brachypterolus sp. in 1989 reduced seed deposition to a total of 1410 seeds m−2 within 0.5 m of the parent plant. The few seedlings that were established occurred in clumps, with densities varying from 1.3 to 7.0 seedlings cm−2 in May and from 0.8 to 7.8 seedlings cm−2 in June 1989. In 1988, total seedling emergence per plot varied between 0.13 and 0.23%. Seed viability and dormancy were major factors influencing seedling establishment. Seed viability was as low as 40% (tetrazolium test), and germination was maximized in the laboratory following a wet stratification at 5 °C for a period of at least 8 wk. Key words: Toadflax, Linaria vulgaris, seed dispersal, seedling establishment, seedling distribution