Gro-Mate Soil Amendment Improves Growth of Greenhouse-grown `Chardonnay' Grapevines

Abstract

<jats:p>Own-rooted, glasshouse-grown `Chardonnay' vines (<jats:italic>Vitis vinifera</jats:italic> L.) were planted in a sand medium to which was added one of five levels of granular Gro-Mate (GM), a commercial humate (0, 8, 16, 32, 64 g/pot; 0 to 35 g a.i./pot). Two other treatments consisted of weekly (1× W) or twice-weekly (2× W) applications of liquid GM, whose cumulative addition over the 28 weeks of the experiment totaled 6.7 and 13.4 g a.i., respectively. Shoot length responded to increasing level of GM in a predominantly cubic fashion, with 32 g/pot resulting in the longest shoots. Fresh and dry weights of leaves, shoots, and roots, as well as leaf count and area, exhibited increasing linear or quadratic trends in response to increased level of granular GM. GM increased soil organic matter, K, Ca, Mg, Fe, Mn, Cu, Na, and S and also increased petiole Fe and lamina P, K, and Fe. Liquid treatment resulted in lower soil pH, organic matter, bulk density, and Fe and higher soil conductivity, NO<jats:sub>3</jats:sub>, P, K, Mg, Cu, Zn, Na, and S than the granular treatments, as well as higher petiole and lamina N and K, lower petiole and lamina P, and lower petiole Zn. Compared to the 1× W treatment, the 2× W produced lower soil bulk density and higher P, lower lamina K, Mn, and Fe; lower petiole Mn; and higher petiole Cu. Plant tissues contained extremely high levels of Mn irrespective of treatment, whereas liquid treatments resulted in high soil NO<jats:sub>3</jats:sub> levels. Although liquid GM cannot be recommended for young grapevines under an application regime such as described here, preplant applications of granular GM may have potential for improving growth of young vines in coarse-textured soils. High granular or excessive liquid applications may result in leaf necrosis and retarded growth.</jats:p>

Leonardite and Fertilizer Levels Influence Tomato Seedling Growth

“…Additions of 1/3 leonardite (the highest level) plus fertilizer increased plant height 40%, total leaf area 160%, shoot fresh weight 134%, root fresh weight 82%, shoot dry weight 133%, and root dry weight 400%. These results confirm those of other researchers (Ayuso et al, 1996;Rauthan and Schnitzer, 1981;Reynolds et al, 1995;Tan and Nopamornbodi, 1979), who reported that moderate levels of humic substances enhanced plant growth whereas high levels inhibited it. Although not measured, plants that responded most to leonardite had larger, darker green leaflets than those that did not respond.…”

“…However, increasing the leonardite content to 1/2 inhibited growth. Similarly, negative effects following application of high levels of humic substances have been observed on shoot and root dry weight of barley (Hordeum vulgare L.) (Ayuso et al, 1996), shoot growth of 'Chardonnay' grapevines (Reynolds et al, 1995), and shoot and root dry weight of cucumber plants (Rauthan and Schnitzer, 1981). High levels of humate can reduce uptake of N and some micronutrients (Ayuso et al, 1996;Rauthan and Schnitzer, 1981;Tan and Nopamornbodi, 1979).…”

“…Humic substances are a primary constituent of leonardite and can be classified into humic acid, fulvic acid, and humin depending upon their solubility in alkali and acid (Schnitzer and Khan, 1972). With adequate mineral nutrition, humic substances can promote the growth of 'Chardonnay' grapevines (Vitis vinifera L.) (Reynolds et al, 1995), cucumber plants (Cucumis sativus L.) (Rauthan and Schnitzer, 1981), corn plants (Zea mays L.) (Tan and Nopamornbodi, 1979), and tomato seedlings (Bryan, 1976). These positive effects of humic substances are often correlated with enhanced macronutrient uptake, as well as their ability to complex transition metals such as Cu, Zn, Fe, and Mn (Chen and Aviad, 1990).…”

“…These positive effects of humic substances are often correlated with enhanced macronutrient uptake, as well as their ability to complex transition metals such as Cu, Zn, Fe, and Mn (Chen and Aviad, 1990). In contrast, excessive concentrations of humic substances can inhibit growth (Ayuso et al, 1996;Bryan, 1976;Rauthan and Schnitzer, 1981;Reynolds et al, 1995). These inhibitory effects have been correlated with the presence of excessive ligands, which reduce micronutrient availability to plant roots (Ayuso et al, 1996;Rauthan and Schnitzer, 1981).…”

Leonardite Influences Zinnia and Marigold Growth

“…With adequate mineral nutrition, root and shoot growth stimulation has been commonly observed in plants treated with humic substances (Bryan, 1976;Pertuit et al, 2001;Rauthan and Schnitzer, 1981;Reynolds et al, 1995;Tan and Nopamornbodi, 1979). Leonardite has promoted root growth in geranium [Pelargonium ×hortorum (L.) H.…”