• Corpus ID: 93462017

The use of organic biostimulants to reduce fertilizer use, increase stress resistance, and promote growth

@inproceedings{Sivaramakrishnan1997TheUO,
  title={The use of organic biostimulants to reduce fertilizer use, increase stress resistance, and promote growth},
  author={S. Sivaramakrishnan},
  year={1997}
}

• S. Sivaramakrishnan
• Published 1997
• Chemistry

High quality organic biostimulants can stimulate plant growth, providing excellent growth and yield, with up to a 50% reduction in fertilizer use. These compounds are essentially, a stress vitamin mix for plants. They were developed for use in tissue culture of refractive or sensitive tissue explants. Research and practice has shown that these compounds can work under soil conditions, as well as in tissue culture. They work best on plants under water, cold, nutrient, and/or biotic stress. In well watered and heavily fertilized plants little effect of these compounds may be manifested. The carrier for most biostimulants is a mix of humic substances and marine algal extracts; the carrier itself has slight activity as an organic biostimulant, however, the most active components are the stress vitamins. Ascorbate is the most active substance, followed by casein hydrolysate. In addition to acting as an antioxidant, ascorbate appears to promotes xylem formation. Under proper conditions, organic biostimulants promote nutrient uptake, acting as both a phosphorus, nitrogen, potassium and micronutrient pump. Thus, seedlings treated with them develop better vascular systems (in the case of pines-more and larger diameter tracheids and thicker walls) to transport water and nutrients, and are more efficient in nutrient uptake due to a larger root system. Recent results in our laboratory suggest that the biostimulant treated plants are more resistant to insects, possibly because they are more vigorous, and can produce more of the energetically expensive defensive compounds like polyphenols. Organic biostimulants, a by-product of biotechnology research, can improve field competitiveness, nutrient use efficiency, and stress resistance of plants (see Berlyn and Beck 1980; Berlyn et al. 1990; Russo and Berlyn 1990; 1992; Russo and Berlyn 1994). Because of these properties, they can decrease reliance on chemicals and tillage, and improve plant health. We do not claim that this approach can completely replace the use of agricultural chemicals. It is a truism that where agricultural chemicals are used, people have enough to eat, and where they are not used, people do not. The modern agricultural practices of developed countries have been highly successful in food production. However, these systems rely on high mechanization, high fertilizer, high herbicide, high fungicide, high pesticide, and high use of fossil fuel energy. Any alternative system that can decrease reliance on fossil fuels and minimize the disturbance of the ecosystem, promotes sustainability and helps preserve the food and fiber supply for future generations. This is increasingly important in view of the limited reserves of fossil fuels that are so necessary in the current high energy agricultural, forestry, and horticultural systems. Our approach is to provide one type of alternative that has less reliance on xenobiotic chemical inputs, and more reliance on the inherent physiological capacities of plants and the other organisms of the rhizosphere. This methodology can be used in urban and suburban systems, as well as in nurseries, agriculture and forested ecosystems. Roots is an organic biostimulant developed by this laboratory. It stimulates plant growth, providing optimum yield with up to a 50% reduction in fertilizer use. Essentially, Roots is a stress complex for plants. It utilizes many of the organic supplement components developed for use in biotechnology over the past 40 years. These components are used in standard plant tissue culture media where the object is to stimulate fragile tissues and cells to grow in an in vitro (foreign) environment that is stressful to them. These biostimulants alleviate some of the stress, and permit these explants to grow and differentiate depending on the other constituents of the tissue culture media. In the 1970's, the senior author experimented with using these same supplements for stress alleviation in the soil environment. Roots and its derivatives are the current result of this research. It is based on long experience in plant tissue culture (cf. Berlyn 1962). Despite their potential autotrophic capacity, plants are seldom situated in optimal conditions where such capacity can be fully realized. For example, when isolated plant roots are grown in tissue culture, they have to be supplied with B-vitamins because roots do not synthesize the B-vitamins they need for growth. In the intact plant, roots get most, if not all, their 13 vitamins from the leaves. In a well watered and fertilized plant growing in a growth room or greenhouse at optimal temperatures, the leaves are able to supply all the B-vitamins (and other substances) the roots need, but under the multiple stresses usually present in the field, this may not be the case. In such situations we have demonstrated that organic supplements improve plant health (Russo and Berlyn 1990). It is difficult to mimic these multiple stress environments in greenhouses or growth rooms and, in general, potted plant environments are quite different from those in the field. Nevertheless, we have found field data to show fairly good correspondence with our tissue culture, greenhouse, and growth room results over the past decade. The main active ingredients in the current Roots formulae are ascorbic acid (vitamin C), casein hydrolysate, myo-inositol and alpha tocopherol (vitamin E), and thiamin. These substances are combined in an aqueous carrier of humic acid and marine algae extracts. The carrier itself has slight activity as an organic biostimulant. However, the stress vitamin supplements are far more active, even when used alone (Cho and Berlyn, unpublished). The ascorbate is the most active substance followed by casein hydrolysate. In addition to acting as an antioxidant, especially in the glutathione-ascorbate oxidation reduction cycle in the chloroplasts, ascorbate also promotes xylem formation. Roots promotes nutrient uptake, acting as both a phosphorus, nitrogen, potassium and micronutrient pump (Russo 1990). Seedlings treated with Roots generally develop better vascular systems (in the case of pineslarger diameter trachelds, larger lumen diameter and thicker walls [under some conditions]) to transport water and nutrients, and are more efficient ill nutrient uptake due to a larger root system. Although the increased efficiency of nutrient uptake might be expected to increase susceptibility to insects, this does not appear to be the case. Recent results in our laboratory suggest just the opposite. Other studies have corroborated this effect and demonstrated that vitamin C and E are active in insect deterrence (Neupane and Norris 1991 ). The fact that the biostimulant treated plants are more vigorous may enable them to produce more of the energetically expensive defensive compounds like polyphenols. Results in our laboratory have suggested that this is indeed the case for oaks and eastern hemlock (Sivaramakrishnan et al. 1996). This work involves a comparison of the feeding effects of two important insect pests, the gypsy moth Lymantria dispar L. (Lepidoptera: Lymantriidae) and the hemlock woolly adelgid (Adelges tsugae Armand, Homoptera: Adelgidae) on white oak Quercus alba L. and eastern hemlock Tsuga canadensis (L.) (Carr.) respectively. The hypothesis is: (1) insect feeding alters plant anatomy and physiology, leading to a loss of tree health and vigor, and directly or indirectly to death in extreme cases; and (2) organic biostimulants can increase host plant resistance to insect attack by improving health and vigor through improved cell structure and increased production of secondary compounds, such as polyphenols (Sivaramakrishnan, et al. 1996). We have used a modified solution of Roots2 , and mineral nitrogen to create populations of trees of varying degrees of plant health and vigor by varying nutrient, herbivory and defoliation levels. Anatomical and physiological measurements were made to determine the effect of the different treatments. Physiological status is being determined by measurements of photosynthesis, leaf chlorophyll, chlorophyll fluorescence, total phenolics, starch, and carbohydrates, as well as by measurements of growth and plant leaf area. Anatomical changes (cell numbers, cell wall thickness, lumen and tracheid diameters) are being measured using image analysis in conjunction with histological techniques. Secondary chemistry has been measured using the Folin-Denis test. Response of gypsy moth larvae to the experimental treatments is being measured with feeding tests on the leaves. In the case of hemlock fecundity of the hemlock woolly adelgid on the treated and control plants, it is being used to measure the impacts of the treatments on host resistance. In a preliminary study to measure the effect of organic biostimulants on gypsy moth feeding on red oak seedlings, we found that while no significant reduction in feeding was observed, total phenolics in red oak leaves were found to be elevated in foliage treated with organic biostimulants and fed on by gypsy moth larvae. The results were highly significant (Figure 1). Higher levels of total phenolics in oak leaves fed on by gypsy moth larvae have been reported by other workers, and these are negatively correlated with larval growth. In a study conducted on infestation levels of the hemlock woolly adelgid, we found that infestation levels were significantly lower on trees treated with organic biostimulant (Figure 2). This reduction of infestation occurred despite the fact that the trees treated with organic biostimulants grew significantly more in both height and diameter. Figure 1. Induction of phenols in red oak by gypsy moth feeding. Figure 2. Hemlock woolly adelgid densities on seedlings treated with an organic biostimulant as compared to control. Over the past decade, the various versions of the biostimulant have been tested on many species, and it has been beneficial in almost all these tests whi