Masters Theses

Date of Award

8-1961

Degree Type

Thesis

Degree Name

Master of Science

Major

Landscape Architecture

Major Professor

B.S. Pickett

Committee Members

H.D. Swingle, J.S. Alexander

Abstract

The success of many vegetable enterprises depends greatly upon the production of healthy and vigorous plants for field setting. There are many problems confronting the producer in this phase of horticulture. While facilities like greenhouse, plant beds and other equipment must be available and properly controlled, successful plant growing is just as dependent upon the media in which the plants are raised.

During the year 1959 (16), in the State of Tennessee alone, cut flowers, potted plants, florist greens and bedding plants were grown under glass covering an area of 2,236,126 square feet. Vegetables, flower seeds, vegetable seeds and vegetable plants were grown under glass covering 175,972 square feet.

Soil as propagating media has drawbacks and poses many problems. The presence of soil pathogens is an important factor not to be ignored in plant production. Damping-off and related diseases of nursery crops are most frequently caused by soil borne Rhizoctonia solanii, but also by water molds (Phythium and Phybopthora Spp). The eradication of these pathogens is both costly and laborious. The presence of nematodes and noxious weed seeds in the soil causes much damage. The eradication of nematodes from soil involves high cost and labor. Removal of weeds from the seed bed is equally laborious and costly.

Small amounts of various salts are necessary for plant development, but excessive concentrations cause injury or death. Salts accumulate in soils from irrigation water or from application of fertilizers in excessive amounts or by the use of manures gathered in places where they have accumulated large amounts of salts. Such salt accumulations result in death or weakening of the plant making it more susceptible to attack by pathogens.

In general, media used in. growing plants need to be sterilized either chemically or by heat. Plant injury due to toxins, is another of the important problems facing the grower using the conventional treated soil mixes. Soil mixtures high in readily decomposable organic matter are most likely to give injury after steaming. The plants may develop injury, such as stunting, dropping of leaves, root corrosion, or even die.

The problems stated above, led the growers to seek a uniform mixture for raising seedlings and nursery stock successfully. This resulted in the development of the John Innes mixes at the John Innes Horticultural Institution during 1934-39. But these mixes had disadvantages in that variability resulted from the use of composted nonuniform turf. The time involved, space and labor, as well as toxic residues being produced after steaming left much to be desired. These drawbacks led to the development of the University of California system of soil mixes and treatments, in 1941 (I). The physical base of the U. C, -type mix consists of an inorganic material-fine sand, and an organic fraction - sphagnum peat moss properly fertilized. This mix has many desirable features such as, chemical uniformity and relative inertness, good drainage and aeration, relatively inexpensive, light in weight and satisfactory water holding capacity.

Investigations in the use of inorganic materials as a base for plant growing has led recently to perlite - an inorganic material of volcanic origin. Much work has been done at the Texas Agricultural Experiment Station (10), and is being done in other places on the use of perlite for raising ornamental plants, but work on its use as a media for raising vegetable plants is meagre.

The object of the present study is to evaluate the use of the inorganic material perlite in combination with organic fraction peat moss in raising vegetable plants. The investigation aims at bringing out the effect of various combinations of such media on the germination, growth rate and yield of plants.

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