Watermelon, Citrullus lanatus (Thunb.) Matsum. & Nakai, crops are continuously exposed to soilborne diseases. In many areas of the United States, greenhouse-raised watermelon seedlings are transplanted to the field to allow for early crop establishment and early fruit production. This practice can result in weakened root systems, which potentially make the plant prone to premature senescence and reduce crop productivity. Mycorrhizal fungi have been reported to improve plant growth in many crops through enhanced root growth and function. We hypothesized that amending potting mixes with commercial inocula of mycorrhizal fungi during seeding of watermelon in a greenhouse would improve watermelon production when seedlings were transplanted to the field. Colonization of watermelon roots with mycorrhizal fungi from three commercial formulations was compared with the colonization of onion roots to confirm the efficacy of the mycorrhizae. Two inocula of mycorrhizal fungi that resulted in colonization of watermelon roots were tested in the field and glasshouse for their potential to improve watermelon production. MycoApply improved early plant growth in two tests, one under Meloidogyne incognita-infested conditions in loamy sand and another at two phosphorus fertilizer levels (0 or 22 kg·ha−1 P) in a loam soil. Mycor Vam Mini plug improved early fruit yield in soil infested with M. incognita. Application of Myconate (formononetin), a potential enhancer of colonization with mycorrhizae, increased early fruit yield in M. incognita-infested soil. Myconate had positive effects when potting mixes were not amended with inoculum of mycorrhizal fungi, but reduced watermelon growth when mycorrhizal fungi were supplied in the potting mix. In glasshouse tests, inoculation with mycorrhizal fungi did not suppress disease. Mycorrhizal fungi inoculations improved early plant establishment and increased the most valuable early fruit yield under some environmental stress conditions but did not increase total fruit yields.
Andreas Westphal, Nicole L. Snyder, Lijuan Xing, and James J. Camberato
Aimin Liu and Joyce G. Latimer
The growth of `Mirage' and `StarBrite' watermelon [Citrullus lanatus (Thunb.) Matsum. and Nakai] transplants were evaluated in TODD 125, 100A, 150, 175, and 200 flats with root cell volumes of 18, 26, 36, 46, and 80 cm3, respectively. The effects of rooting volume restriction (RVR) on the number of leaves developed, leaf expansion, and shoot and root dry weight gain increased with time measured at 5, 10, 15, or 20 days after seedling emergence (DAE) for `Mirage' or 4, 8, 12, or 16 DAE for `StarBrite'. Generally, the greatest effect of RVR occurred between 10 and 15 DAE for `Mirage' and 8 and 12 DAE for `StarBrite' for most measurements. Root: shoot dry weight ratios generally were similar among the cell volumes. In a 1993 field test with `StarBrite' grown in the previously described flats, transplants from the TODD 125s produced the least growth and the poorest yield in terms of fruit per plant, total number of marketable fruit, and total yield. Transplants from TODD 200s produced a higher total yield than plants from other cell volumes.
Joseph M. Kemble, Jeanine M. Davis, Randolph G. Gardner, and Douglas C. Sanders
The influence of flat cell volume (cavity containing growing medium) on transplant growth and development of NC 13G-1, a compact-growth-habit, fresh-market tomato (Lycopersicon esculentum Mill.) breeding line, was compared to that of a normal growth habit line, NC 8288. Transplants of each line were produced in four cell volumes (3.3, 27, 37.1, and 80cm3) for 5 weeks, evaluated and then transplanted to larger containers, and grown until anthesis. During the first 5 weeks after seeding, plant dry weight did not differ between the lines; however, plant height of NC 13G-1 was ≈60% of the height of NC 8288. For both lines, number of days from sowing to anthesis decreased as root cell volumes increased. For space-efficient production of large quantities of compact-growth-habit tomato transplants, flats with root cell volumes as small as 27 and 37 cm3 can be used without greatly delaying anthesis.
Nancy Kokalis-Burelle, C.S. Vavrina, M.S. Reddy, and J.W. Kloepper
Greenhouse and field trials were performed on muskmelon (Cucumis melo) and watermelon (Citrullus lanatus) to evaluate the effects of six formulations of plant growth-promoting rhizobacteria (PGPR) that have previously been shown to increase seedling growth and induce disease resistance on other transplanted vegetables. Formulations of Gram-positive bacterial strains were added to a soilless, peat-based transplant medium before seeding. Several PGPR treatments significantly increased shoot weight, shoot length, and stem diameter of muskmelon and watermelon seedlings and transplants. Root weight of muskmelon seedlings was also increased by PGPR treatment. On watermelon, four PGPR treatments reduced angular leaf spot lesions caused by Pseudomonas syringae pv. lachrymans, and gummy stem blight, caused by Didymella bryoniae, compared to the nontreated and formulation carrier controls. One PGPR treatment reduced angular leaf spot lesions on muskmelon compared to the nontreated and carrier controls. On muskmelon in the field, one PGPR treatment reduced root-knot nematode (Meloidogyne incognita) disease severity compared to all control treatments.
Mary A. Rogers
vegetable transplant production, and point to future research needs for organic agriculture. Fig. 1. Lettuce and mustard greens growing in a vertical gutter system in soilless, organic media in a passive solar heated greenhouse at Paradox Farm, Ashby, MN
Paige L. Herring, Abbey C. Noah, and Helen T. Kraus
-borne pathogens found common in peatmoss such as plant fungi [ Fusarium oxysporum and Sclerotinia minor among others ( Veeken et al., 2005 )]. Composts are an attractive option for peat substitutes in transplant production ( Bustamante et al., 2008 ). Composts
Valérie Gravel, Martine Dorais, and Claudine Ménard
certified organic transplants production because the main source of nutrients must be provided by the growing medium. This increases the challenge of producing healthy sweet pepper transplants with a balance between the shoot and the root within a small
David O. Cliffe
Transplant production using containerized cell trays has been practiced in Australia for 15 years, predominantly with the Todd seedling trays. This paper attempts to cover the many methods of transplant production that have evolved in Australia, a country with a unique climate and a horticulture industry requiring a diversity of crops throughout the year. This paper identifies areas that need more research to reduce costs and expand transplant production to encompass a wider range of plant species.
George E. Boyhan, Juan Carlos Diaz-Perez, Chris Hopkins, Reid L. Torrance, and C. Randy Hill
spacing ( Boyhan et al., 2001a ). All of this relies on hand labor, which adds to the cost of production. Current University of Georgia Cooperative Extension Service fertilizer recommendations for onions includes 130 lb/acre N for transplant production and
Abbey C. Noah, Helen T. Kraus, and Paige L. Herring
Due to its favorable physical and chemical properties, peatmoss ( Sphagnum sp.) has, for some time, been the main component of substrates for vegetable transplant production ( Abad et al., 2001 ; Raviv et al., 1998 ). However, the high price of