Conclusions and possibilities of this organic biostimulant for NFTs. The organic biostimulant Roots~® offers significant opportunities to increase plant growth, according to findings from current university research and field trials. Improved root and shoot growth, greater root growth potential, and better stress resistance are consistent results obtained from using this OB.
The most important possibility for the future of this organic biostimulant may be its ability to cut down chemical fertilizer without affecting growth. Preliminary research done by Russo (1989, unpublished) showed that in the presence of the biostimulant, coffee seedlings treated with half the amount of fertilizer yielded the same shoot biomass and higher root biomass than those fully fertilized. The OB increased acetylene reduction, root weight and leaf area inA!nus acuminata (Russo and Berlyn 1989). The OB also increased the stem production of Gliricidia sepium. Stem fresh weight in the treated plants was 48% (significant at 95% level) higher than the untreated plants. Most of this was xylem, the water and mineral conducting part of the vascular system. The structural difference is striking. Although the cell wall thicknesses were not affected greatly by the OB as shown by Berlyn et a!. (1990), the water and nutrient transporting capacity of the treated trees was far greater than the untreated trees.
The greater amount and hydraulic conductivity of the vascular system may be the basic function of the biostimulant. For example, we have found that the treated plants have much more chlorophyll and, concomitantly, greater photosynthetic capacity. However, both chlorophyll biosynthesis and photosynthesis are sensitive to water deficits, even relatively mild ones. Thus the effect of Roots-® may be to keep the tissue moist so that it can produce and maintain a more optimum chlorophyll content and utilize more of its basic photosynthetic capacity.
Chlorophyll synthesis also requires a number of nutrients (especially nitrogen, iron and magnesium) and with greater translocation capacity the treated plants can provide more of these nutrients at the sites of chlorophyll synthesis. With respect to coffee we have found that the nutrient content of the foliage of plants given half the normal fertilizer content but treated with OB was essentially the same as that of fully fertilized plants and about double that of plants given half fertilization but not treated with the OB. These investigations are continuing.
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