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Transplant survivability is important in achieving consistent economic yields in sweetpotatoes. We are conducting a series of studies that investigate the role of transplant quality in sweetpotato yield. In 2004, in addition to investigating the role of transplant diameter, we also investigated the influence of transplant water (about 6 oz per hill) on stand and yield. Even though rainfall events were regular and mean rainfall during the growing season was above average for the year, there was a significant increase in US#1 yield (23.57%) among plots derived from thick transplants (≥0.25 inches, no transplant water) versus thin transplants (no transplant water). There was a 44.16% increase in US #1 yield among plots planted with thick transplants vs. plots with thin transplants (with transplant water). In 2005, there was also a significant difference (14%) in US #1 yield between plots planted to thick and thin transplants, respectively. This indicates the possible role of transplant thickness on stand and yield. We also investigated the relationship between root spacing during bedding on cutting diameter as well as a farmer's practice of planting two transplants per hill. In both preliminary tests, no differences among the treatments were observed. Additional studies are planned to investigate the possible use of chemical-based treatments to enhance transplant thickness and survivability.
Abstract
‘Beauregard’ sweet potato [Ipomoea batatas [L.] Lam.] was developed by the Louisiana Agricultural Experiment Station to combine resistance to diseases and insects of local importance with good horticultural and culinary characteristics. This cultivar, first designated L82-508, is named after Louisiana's renowned civil engineer and “Napo-lean in Grey,” Gen. P.G.T. Beauregard.
The yield of three generations of virus-tested plants of `Beauregard' sweetpotato (Ipomoea batatas) was assessed in Louisiana over a 4-year period in 15 yield trials. Treatments included virus-infected foundation `Beauregard', virus-tested `Beauregard' mericlone, B-63 [generation 1 (G-1)], and three generations of B-63 (G-2, G-3 and G-4). Generations refer to the number of continuous years virus-tested plants are grown in the field. Use of G-2 virus-tested `Beauregard' transplants increased yields of U.S. no. 1 grade roots by 16% in comparison with virus-infected, foundation `Beauregard'. Total marketable yield was also higher (11%) using B-63 G-2 transplants in comparison to virus-infected, foundation `Beauregard'. Use of B-63 (G-1), G-3 and G-4 generation transplants did not increase yields in any grade in comparison to virus-infected, foundation `Beauregard' by planting plots amidst virus-infested sweetpotato fields. Generation one B-63 transplants were greenhouse grown and often appeared less robust after planting. Yet we were unable to show significant yield differences between greenhouse derived B-63 (G-1) and field-grown B-63 (G-1) in separate tests; other factors may be involved.
Yield tests and evaluation of selected storage root and vine characters were conducted among 12 `Beauregard' sweetpotato [Ipomoea batatas (L.) Lam.] mericlones. Maximum yield differences were 43%, 48%, 79%, and 40% for U.S. #1, canners, jumbos, and total marketable yield, respectively. Additive main effect and multiplicative interaction (AMMI) biplot analysis was useful in graphically presenting the yield differences and stability patterns of mericlones. Differences were also detected in vine length, internode diameter, and internode length. Digital image analysis of U.S. #1 storage roots also revealed differences in storage root minor axis length, roundness, and elongation attributes. The results provide valuable information for enhancing current methods of evaluation and selection of mericlones for inclusion in sweetpotato foundation seed programs.