Six greenhouse trials of five commercial products marketed as systemic resistance (SR) and plant growth promotion (PGP) inducers were evaluated on tomato (Lycopersicon esculentum Mill.) over a 21-month period. The effect of the inducers on treated plants was measured by monitoring plant growth and disease suppression after inoculation with either plant pathogenic bacteria or nematodes. The commercially available SR/PGP inducers included a bacterial suspension [Companion (Bacillus subtilis GB03)], two plant defense elicitors with nutrients (Keyplex 350DP plus Nutri-Phite, and Rezist with Cab'y), natural plant extracts (Liquid Seaweed Concentrate and Stimplex), and a synthetic growth regulator (Actigard 50W). Growth enhancement was noted in some trials, but the parameter of growth affected often varied with trial. Response to Actigard treatment included significant suppression of bacterial spot [Xanthomonas campestris pv. vesicatoria (Xcv)] in three of the six trials. Companion, Keyplex 350DP plus Nutri-Phite, Rezist and Cab'y, and seaweed products induced only partial disease suppression of bacterial spot in inoculated tomato plants. The alpha-keto acids plus nutrients (Keyplex 350DP plus Nutri-Phite) increased plant growth by 14.3% and improved root condition compared to the untreated control following exposure to nematodes. Results are encouraging, if not consistent, and with a greater understanding of the SR system and the conditions related to product efficacy, such materials may become effective tools for production agriculture.
Charles S. Vavrina, Pamela D. Roberts, Nancy Kokalis-Burelle, and Esa O. Ontermaa
Diánez Fernando, Santos Milagrosa, Carretero Francisco, and Marín Francisco
antagonistic activity and plant growth promotion in pepper ( Diánez et al., 2016 ). Each isolate was grown on potato dextrose agar (PDA, Bioxon, Mexico City, Mexico) for 15 d at 25–27 ± 2 °C under dark conditions. Spore suspensions were prepared in sterile
Amal de Silva, Keith Patterson, Craig Rothrock, and James Moore
The highbush blueberry cultivar Bluecrop was inoculated with potential plant growth-promoting (PGPR) candidates, including bacterial inoculants Pseudomonas fluorescens (Migula) (strains Pf 5, PRA 25, 105, or 101), Bacillus pumilus (Mayer and Gottheil) (strain T4), Pseudomonas corrugata (Roberts and Scarlett) (strain 114), and fungal isolates Gliocladium virens (Miller et al., Von Arx) (strain Gl.21) and Trichoderma harzianum (Rifai) (strain T 22). Addition of G. virens to pasteurized soil increased leaf area and the number of leaves produced in a 4-month growth period, as well as shoot content of P, Zn and Cu in 1997. Treatment with P. fluorescens Pf 5 increased leaf area and stem diameter. In nonpasteurized soil, plants inoculated with G. virens had greater leaf area, stem diameter, shoot and root dry weight, and more leaves per plant. These results demonstrate the potential of G. virens for increasing growth when used to inoculate blueberry plants in the nursery or at transplanting.
Abu Shamim Mohammad Nahiyan and Yoh-ichi Matsubara
differed with AMF species. Ozgonen and Erkilic (2007) reported that growth promotion and tolerance to Phytophthora capsici had no correlation with the mycorrhizal colonization levels in peppers. In the present experiment, we could not clarify AMF fungal
Tomohiro Okada and Yoh-ichi Matsubara
Tolerance to fusarium root rot and the changes in free amino acid contents in mycorrhizal asparagus (Asparagus officinalis L., cv. Welcome) plants were investigated. Sixteen weeks after inoculation of arbuscular mycorrhizal fungus (AMF; Glomus sp. R10), mycorrhizal plants showed higher dry weight of ferns and roots than non-mycorrhizal plants, and AMF colonization level in a root system reached up to 73.3%. Ten weeks after Fusarium oxysporum f. sp. asparagi (Foa; MAFF305556, SUF1226) inoculation, disease incidence and the severity of symptoms were eased and disease indices were low as less than 20 in mycorrhizal plants compared with non-AMF plants in the both isolates. As for the changes in free amino acid, total free amino acid contents in ferns and roots were higher in AMF plants than non-AMF plants 16 weeks after AMF inoculation. In this case, eight constituents of amino acids in ferns and 16 in roots increased in AMF plants; in particular, arginine and gamma-aminobutyric acid (GABA) showed considerable increase in both ferns and roots in AMF plants. In the Foa culture by Czapec-Dox medium in vitro, suppression of Foa propagation was recognized by the addition (0.1, 1%, w/v) of arginine and GABA. From these findings, plant growth enhancement and tolerance to fusarium root rot occurred in mycorrhizal asparagus plants, and the disease tolerance was supposed to be associated with the symbiosis-specific increase in free amino acids.
Ainhoa Martínez-Medina, Antonio Roldán, and Jose A. Pascual
Rabeendran, N. Moot, D.J. Jones, E.E. Stewart, A. 2000 Inconsistent growth promotion of cabbage and lettuce from Trichoderma isolates NZ Plant Prot. 53 143 146 Schollenberger, C.J. Simon, R
Jong-Seok Park and Kenji Kurata
) were generated in the nutrient solution; 1 cm = 0.3937 inch. Although the reasons for growth promotion by the microbubbles are still under investigation, one of the possibilities is the larger specific surface area of microbubbles when compared with
Joseph W. Kloepper, M.S. Reddy, Choon-min Ryu, and John F. Murphy
Use of beneficial rhizobacteria to enhance growth and induce systemic disease protection in transplants. Plant associated bacteria have been studied for the capacity to provide plant growth enhancement and biological disease control. “Rhizobacteria” are bacteria from the rhizosphere that have the capacity to colonize plant roots following introduction onto seeds or into soil. Effects of rhizobacteria on plants may be deleterious, neutral, or beneficial. Beneficial rhizobacteria are termed “PGPR—plant growth-promoting rhizobacteria.” In developmental studies aimed at reducing to practice the concept of induced systemic disease protection mediated by PGPR, we discovered that mixtures of PGPR and an organic amendment into the soilless media used to prepare tomato transplants resulted in highly significant and reproducible plant growth promotion. Time for development of transplants was typically reduced from 6 weeks for controls receiving industry standard fertility and growth regimes to 4 weeks for seedlings grown in soilless mix into which the PGPR had been incorporated. This marked growth promotion was also associated with systemic protection against pathogens. When transplants were inoculated with the tomato spot pathogen, significantly fewer lesions developed on plants grown in the biological system than on control plants. Similar effects on plant growth and systemic disease protection were seen with cucumber, bell pepper, and tobacco, suggesting that the benefits are not highly crop or cultivar specific. Results of recent field studies will be presented. We conclude that incorporation of PGPR into soilless mixes is a technologically useful and feasible way to deliver benefits to transplants.
Hae-Jeen Bang, Soo-Jung Hwang, Hee Chung, and Jung-Myung Lee
Soybean sprouts are one of the most-favored traditional vegetables around the world. The sprouts are usually consumed 7 to 10 days after sowing depending upon the growing conditions. High-quality sprouts should have less secondary roots, short and well-swollen hypocotyls in pure white color, and small cotyledons in hooked position. Cytokinins were reported to be effective in producing such sprouts by promoting sprout growth while inhibiting the excessive hypocotyl elongation and secondary root growth. Seeds of four soybean cultivars with different characteristics were soaked in water for 4 h and, 2 to 3 h after the imbibition, the seeds were soaked again in solutions of different cytokinins such as benzyladenine (BA), BA-riboside (BAR), BPA, 2iP, 2iP-riboside, 4-CPPU, and kinetin-riboside (KR) for 10 min. After the treatment, the sprouts were grown in a plastic tube (25 cm height × 10.5 cm diameter) a dark culture room with ample watering every 4 h. After 7 days of growth, uniform samples were taken from each treatment and the sprout characteristics were examined. Some cytokinins such as BA, BAR, 4-CPPU were highly effective in promoting the sprout growth (fresh weight) even though the hypocotyl length was markedly reduced. Other cytokinins such as 2iP, 2iPR, and KR had no effect on sprout growth. Hypocotyl diameter was markedly increased by BA and 4-CPPU treatment, thus resulting in short, strong and good quality sprouts. Cultivars responded differently to cytokinin treatment by showing different growth promotion depending upon the sprout parts. Injury-like symptoms, abnormal and twisted heads or cotyledons, appeared in cytokinin-treated sprouts at high concentrations and the symptoms were severe when the sprouts were grown at high temperatures. In all the cultivars tested, BAR appeared to be better than others in terms of sprout quality and growth promoting characteristics.
Steven F. Vaughn, Mark A. Berhow, and Brent Tisserat
through 3-MPAN applications is obtainable both in vivo and in vitro. Our results suggest that growth promotion for a variety of plants is possible using (3-methoxyphenyl)acetonitrile as an aqueous foliar spray. Because very low rates of 3-MPAN were