Three sweet potato cultivars, `Beauregard', `Hernandez' and `Jewel' were transplanted at three different planting dates: June 4, June 21 and July 10, with harvest at 106, 109 and 117 days; respectively. Four in-row spacings of 22.9, 30.5, 38.1, and 45.7 cm on a 1 mm spacing between rows were used in each of the planting dates. The highest yields of U.S. No.1 grade potatoes in the cultivar `Beauregard' were produced at the 22.9 cm spacing in the first two planting dates and at 30.5 cm in the July 10 planting date. The highest yields of U.S. No.1 grade potatoes in the cultivar `Hernandez' were produced at 38.1 cm in all three planting dates. With the cultivar `Jewel' in the June 4 planting there was only a small difference in yield of U.S. No.1 potatoes at the 22.9, 30.5 and 38.1 cm spacings. In the June 21 and July 10 plantings the highest yields were produced at the 22.9 cm spacing. The 45.7 cm spacing produced the highest number of marketable roots per hill in all three cultivars.
W.A. Mulkey and W.B. McLemore III
Lewis W. Jett and W.A. Mulkey
Nitrogen effects on `Beauregard' sweetpotato were investigated from 1992 to 1995 at the LSU Sweet Potato Research Station to determine the optimal rate and timing of nitrogen application. Five rates of preplant nitrogen were applied: 0, 33.6, 50.4, 67.2, and 84 kg·ha–1. Increasing the rate of nitrogen to 50.4 kg·ha–1 significantly increased marketable yield. Five treatments of pretransplant/sidedress nitrogen (kg·ha–1) were applied: 0/0, 50.4/0, 0/50.4, 33.6/16.8, and 16.8/33.6. Withholding nitrogen resulted in significantly more storage root initiation 21 days after transplanting (DAT). Application of 50.4 kg N/ha 21 DAT resulted in significantly greater yields of US #1 sweetpotatoes in 1992 and 1995 and equaled the pretransplant nitrogen treatment in 1993 and 1994.
W.A. Mulkey and J.H. Hernandez
Foundation sweetpotato [Ipomoea batatas (L.) Lam] seedstock has been produced annually at the Sweet Potato Research Station since 1949. Breeder seedstock is selected from superior hills and used for the following year's foundation seedstock. Fields are intensely monitored after planting until harvest to remove off-type plants, mutations, etc. Seedstock is harvested from August through October, stored, graded, and repacked beginning in late January, and then made available to the growers during the early spring.
W.A. Mulkey, W.B. McLemore III and T.P. Talbot
In preplant nitrogen studies with the `Beauregard' Variety maximum yields of U.S. No. 1 grade roots are produced using 50.4 kg/ha N. In 1992 studies were initiated to determine the effect of preplant N rates on storage root set and yield. Preplant N rates ranged from 0 to 84 kg/ha in 16.8 kg/ha increments. Two plots each of 0, 16.8 and 33.6 kg/ha were included so sidedress applications could be made to bring one of the treatments to the 50.4 kg/ha N level 30 days after transplanting. The 0 kg/ha N treatment had significantly more storage roots per plant than all other treatments 21 days after transplanting and more vine growth measured by weight. The 0 and 16.8 kg/ha treatments had significantly more storage roots 26 days after transplanting. At 26 and 35 days after transplanting vine growth was greater in 16.8 kg/ha N treatment. The 0 plus 50.4 kg/ha N sidedress treatment produced the highest yield of U.S. No. 1 grade roots with the highest number of marketable roots per plant (5.0). Similar results were obtained in the 1993 studies.
W.A. Mulkey, W.B. McLemore III and T.P. Talbot
In-row spacing studies have been conducted with `Beauregard!, `Hernandez' and some promising seedlings in the LSU Agricultural Center sweet potato breeding program. May, June and early July plantings are evaluated on 1 m rows with in-row spacings of 23, 30, 38, and 46 cm. With the variety `Beauregard' early May plantings (1-15th) yields of U.S. No.1 grade roots are higher at the 30 cm spacing. From mid-May to June 20th higher yields of No. 1's are produced at a 23 cm spacing. Higher yields are obtained in the late June-early July plantings at the 30 cm spacing. Highest yields overall are produced in late May-early June plantings with `Beauregard'. With the `Hernandez' variety the highest yield of U.S. No.1 grade roots have been produced at a 38 cm in-row spacing during all three planting seasons, with the highest yields overall being produced in the May plantings. Days to maturity are reduced in early `Hernandez' plantings. Results of limited in-row plant spacing with the seedling `LU7-59' are identical to the `Beauregard' variety.
Regina P. Bracy, R.L. Parish and W.A. Mulkey
A cultural system consisting of precision seeding on shaped beds, followed by cultivation using mechanically guided equipment, was developed and evaluated with several vegetable crops. The precision cultural system allowed for growing the crops at high plant populations by using precision planting and exact cultivation of multiple narrow rows of plants on wide beds. Eight field experiments were conducted from 1987 to 1989 on broccoli (Brassica oleracea var. botrytis L.), cabbage (Bra&a oleracea var. capitata L.), mustard (Brassica juncea var. crispfolia L.), and spinach (Spinacia oleracea L.) to evaluate production of these crops on single- and multiple-row configurations on narrow (1 -m) and wide (2-m) beds. The precision cultural system was assessed to be an excellent method for production of the small-seeded crops that were tested. Yield was highest for cabbage, mustard, and spinach planted in six rows on 2-m beds compared with four-, two-, or one-row beds. Multiple-row configurations did offer yield advantages over the single-row configuration for broccoli production.
B. Buckley, W.A. Mulkey, J.D. Griffins, K.C. Peel, T. Talbota and W. Russell
Four southernpea cultivars were evaluated for fresh market mechanical harvest at Calhoun, Chase, and Ruston, Louisiana. The cultivars were 'Encore', 'Royal Cream', 'Queen Anne', and 'Texas Pinkeye'. In addition, 'Early Acre' and breeding lines AR87-435 and AR91-135 were also evaluated at Chase. The marketable yield from mechanical harvest ranged from 1075 kg·ha-1 for 'Royal Cream' at Calhoun and Ruston to 1855 kg·ha-1 for 'Encore' at Calhoun and Chase. Low concentrated maturity was the main factor limiting marketable yield. The percent mature pods at harvest was near 55 for most cultivars. Yield efficiency of mechanical harvest vS. hand harvest was above 75% for most cultivars. The percent trash resulting from machine harvest ranged from 6 for AR91-135 to 24 for 'Queen Anne'.