Ajay Nair

Date of Award

2006

Level of Access Assigned by Author

Campus-Only Thesis

Degree Name

Master of Science (MS)

Department

Horticulture

Advisor

Donglin Zhang

Second Committee Member

John M. Smagula

Third Committee Member

Jinhua Li

Abstract

Landscape and ornamental plant production is a vital component of the landscape and nursery industry in the United States. Over the past decade, floriculture and nursery crops have been one of the fastest growing sectors in U.S. agriculture. According to the Floriculture and Nursery Crops Situation and Outlook Yearbook (June 2005) of the Economic Research Service, USDA, floral and nursery crops contributed $15.7 billion out of the estimated $45 billion in U.S. horticulture sales in 2004. The nursery and greenhouse industry now represents about 12 percent of the total agricultural product value and is the fifth largest segment of United States agriculture. Stewartia pseudocamellia Maxim. is an ornamental tree which is prized for its camellia-like flowers, intense fall color, and exfoliating bark. In spite of having such outstanding ornamental features and values, Stewartia pseudocamellia is not readily available for landscaping in the horticultural trade due to production difficulties. Cutting propagation poses a problem as rooted cuttings often die soon after overwinter storage. Research was thus undertaken to propagate Stewartia pseudocamellia from semihardwood and hardwood cuttings and compare their overwinter survival. Experiments were designed to study the effects of type of cutting, rooting hormone, media, fertilizer application, and overwinter temperature on the overall success of vegetative propagation. Taking cuttings of Stewartia pseudocamellia in August compared to July resulted in greater rooting percentages but did not significantly affect the overwinter survival. For July and August cuttings, overall overwinter survival was greatest when nitrogen was excluded regardless of propagation date. Semihardwood cuttings rooted and survived in higher proportions when compared to hardwood cuttings. Plants rooted in Perlite + Perennial Mix (1 : 1 by volume) had 82.4% overwinter survival, compared to 17.9% in Perlite + Promix (1 :1 by volume). Rooting hormone formulation comprising of combination of quick dip (5,000 mg/~-K' IBA) and Hormodin #2 (0.3% a.i.) was better when compared to powder (Hormodin #3) or control (without KIBA). The quick dip and powder combination gave good rooting and subsequent overwinter survival and resulted in 82.3% survival compared to 20% in control. The better overwinter temperature was 5 "C, which overwintered 65.6% of newly rooted cuttings. Temperatures lower than -12 "C were detrimental to the plants. Without cold treatment only 2 1.9% of the rooted cuttings survived, which was three times lower than those that received 5 "C treatments. Fertilizer treatment significantly decreased the overwinter survival. Survival rate was 38% for cuttings without fertilizer treatment and 28% for cuttings that received fertilizer treatment. Hardwood cuttings were given rooting hormone and bottom heat treatments, but cuttings failed to root and died. Budbreak occurred prior to root initiation on cuttings leading to their death due to lack of water and nutrients.

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