Browsing by Author "O'Connell, Suzanne"

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    Grafted Tomato Performance in Organic Production Systems: Nutrient Uptake, Plant Growth and Yield.
    (2008-12-09) O'Connell, Suzanne; Mary M. Peet, Committee Chair; Frank J. Louws, Committee Member; Thomas Rufty, Committee Member
    O’CONNELL, SUZANNE. Grafted Tomato Performance in Organic Production Systems: Nutrient Uptake, Plant Growth, and Fruit Yield. (Under the direction of Mary M. Peet.) There are many inherent challenges with growing tomatoes in the Southeast which can be intensified under organic production. Cultivating tomatoes under high tunnel systems may offer a number of benefits and opportunities such as season extension, higher fruit quality, less foliar disease pressure, and protection from extreme weather events. Grafted plants may be uniquely suited to production in organic systems and also high tunnel environments due to their higher stress tolerance, increased crop longevity, more efficient fertilizer use, and soil borne disease resistance. The combination of growing high-value grafted crops under high tunnel structures is an innovative systems approach that can offer new economic opportunities, greater production stability, higher fruit quantity and quality. A baseline greenhouse study with conventional inputs was conducted in 2007, to evaluate the grafting effect on tomato plant growth and nutrient accumulation expressed in the leaf tissue. Grafting treatments included two scion-hybrid rootstock combinations Solanum lycopersicum L 'Trust' or 'German Johnson' grafted on Solanum lycopersicum L. xSolanum habrochaites S. Knapp & D.M. Spooner 'Maxifort', two self-grafted controls, and two non-grafted controls. Both shoot and root growth, were significantly higher in grafted treatments compared to non-grafted treatments. The leaf tissue nutrient concentrations were greater in grafted plants for: N, P, Ca, Mg, S, Fe, Mn, Zn, Cu, and B compared to non-grafted plants. Self-grafted controls had an intermediate values for selected plant growth and nutrient uptake compared to grafted and non-grafted treatments. Values were not different among scion cultivars. In 2007 and 2008, a systems comparison study was conducted at The Center for Environmental Farming Systems in Goldsboro, North Carolina. An organic high tunnel system was compared to an organic field system. Three levels of N inputs were applied to each system. Grafting treatments included two heirloom scion-hybrid rootstock combinations: Solanum lycopersicum L. 'Cherokee Purple' grafted on Solanum lycopersicum L. xSolanum habrochaites 'Maxifort' or 'Beaufort', a self-grafted control (2008 only) and a non-grafted control. System type, N level, and grafting effects on nutrient uptake, plant growth, and fruit yield were evaluated. The high tunnel system produced greater fruit yields for all treatments and hit peak production three weeks earlier compared to the field system. The high tunnel system had a higher incidence of blossom end rot, cat-facing, and cracking but lower incidence of TSWV and insect damage compared to the field system. Mean leaf tissue N concentrations were highly correlated with total harvest weight (>70.4%) in 2008. The N input level effect on yield was not consistent across the two seasons, however, in 2008 both the high and medium N input levels (168 kg ha-1 and 122 kg ha-1, respectively) produced greater total harvest yields compared to the low N level (93 kg ha-1). Grafted plants had higher mean leaf tissue concentrations for: N, P, K, Mn, Cu, Zn, and B but lower concentrations of Mg and Na compared to non-grafted plants. Grafted plants produced a greater fruit yield compared to non-grafted plants in a low disease pressure environment. Grafted plants in the high tunnel system also displayed greater plant growth compared to the non-grafted plants. Self-grafted plants (2008 only) were not different from non-grafted plants in terms of nutrient uptake, plant growth, or fruit yield. Both the 'Cherokee Purple-Maxifort' and 'Cherokee Purple-Beaufort' grafting treatments produced a greater number of fruit in the high tunnel system compared to the field system. The greatest yield response was achieved in the high tunnel system with the 'Cherokee Purple-Maxifort' grafts.
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    Short-term Nitrogen Mineralization and Soil Microbial Response to the Incorporation of Warm-season Cover Crops in Organic Farming Systems.
    (2013-10-18) O'Connell, Suzanne; Nancy Creamer, Chair; Wei Shi, Minor; Julie Grossman, Member; Greg Hoyt, Member; Matthew Krakowsky, Graduate School Representative