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Qiansheng Li, Jianjun Chen, Russell D. Caldwell and Min Deng

This study evaluated the potential for using cowpeat, a composted dairy manure, as a component of container substrates for foliage plant propagation. Using a commercial formulation (20% perlite and 20% vermiculite with 60% Canadian or Florida peat based on volume) as controls, peat was replaced by cowpeat at 10% increments up to 60%, which resulted in a total of 14 substrates. Physical and chemical properties such as air space, bulk density, container capacity, total porosity, pH, carbon-to-nitrogen ratio, and cation exchange capacity of the cowpeat-substituted substrates were largely similar to those of the respective control. However, the electrical conductivity (EC) increased with the increased volume of cowpeat. The 14 substrates were used for rooting single-node cuttings of golden pothos (Epipremnum aureum) and heartleaf philodendron (Philodendron scandens ssp. oxycardium) and three-node cuttings of ‘Florida Spire’ fig (Ficus benjamina) and germinating seeds of sprenger asparagus (Asparagus densiflorus) in a shaded greenhouse. All cuttings rooted in the 14 substrates, and the resultant shoot and root dry weights of golden pothos and ‘Florida Spire’ fig 2 months after rooting did not significantly vary across seven Canadian peat- or Florida peat-based substrates. Shoot dry weights of heartleaf philodendron were also similar across substrates, but the root dry weight produced in the Canadian peat-based control substrate was much greater than that produced in the substrate containing 60% cowpeat. Root dry weight and root length produced in the Florida peat-based control substrate were also significantly greater than those produced in substrates substituted by 60% cowpeat. These results may indicate that cuttings of golden pothos and ‘Florida Spire’ fig are more tolerant of higher EC than those of heartleaf philodendron, as the substrate with 60% cowpeat had EC ≥ 4.16 dS·m−1. Seed germination rates of sprenger asparagus from cowpeat-substituted Canadian peat-based substrates were greater than or comparable to those of the control substrate. Seed germination rates were similar across the seven Florida peat-based substrates. The root-to-shoot ratios of seedlings germinated from both control substrates were significantly greater than those germinated from substrates substituted by cowpeat. This difference could be partially explained by the higher nutrient content in cowpeat-substituted substrates where shoot growth was favored over root growth. Propagation is a critical stage in commercial production of containerized plants. The success in using up to 60% cowpeat in rooting and seed germination substrates may suggest that cowpeat could be an alternative to peat for foliage plant propagation.

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J.H. Dunn, D.D. Minner, B.F. Fresenburg and S.S. Bughrara

We evaluated the effect of fertilization treatments in combination with clippings disposal on perennial ryegrass (Lolium perenne L.) in two adjacent locations. Clippings left on turf during mowing decreased dollar spot (Sclerotinia homoeocarpa F.T. Bennett) in both locations during three summers compared with clippings removed in mower baskets. However, brown patch (Rhizoctonia solani Kuhn) increased during July and Aug. 1995 when clippings were left on turf. Dollar spot was more severe with N (kg·ha–1·year–1) at 120 compared to 240; brown patch was more severe at 240. While clippings disposal had significant effects on disease incidence, implementation may not be practical because of the contrary responses of the observed diseases to this management approach.

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James D. McCreight, Jack E. Staub, Anabel López-Sesé and Sang-Min Chung

Genetic variation among 378 melon (Cucumis melo L.) germplasm accessions collected in India in 1992 and 26 accessions in China in 1994 was evaluated with 19 isozyme loci. `Top Mark' and `Green Flesh Honeydew', which represented two distinct C. melo ssp. melo L. groups, Cantalupensis and Inodorus, respectively, were used as reference cultivars. Genetic distances among accessions were calculated, and an initial cluster analysis using these distances resulted in 148 groups of varying size, ranging from two to 47 accessions. One accession from each of the 148 groups was chosen at random and used in a second cluster analysis that identified 11 accession groups. Group 1 was unique and consisted of only two C. melo ssp. agrestis (Naudin) Pangalo accessions. Two large branches were detected at cluster node 2. One branch was comprised of three groups of 3, 12, and 34 accessions, while the other branch contained seven groups of 2, 3, 14, 16, and 47 accessions, and the reference cultivars. Of the 148 accessions, 132 were from 41 sites in Rajasthan and Madhya Pradesh, India, which were distributed unequally across the 11 groups. The 14 Chinese accessions originating from seven provinces were also dispersed unequally in the four major cluster groups. `Top Mark' and `Green Flesh Honeydew' were genetically distinct and uniquely clustered in the same group. These results indicate that additional collections of melon germplasm should be made in eastern and southern India.