The Neem tree is of ornamental, revegetation, biomass and medicinal value. The compound azadirachtin, which is derived from Neem seeds, is commercially used for insecticidal properties. In a 2×2 factorial experiment, Neem seedlings were either colonized with the mycorrhizal fungi Glomus intraradices or noninoculated and fertilized with full strength Long Ashton Mineral Solution at 11 or 22 ppm P. Mycorrhizal and P main effects were highly significant (p-value<0.001) with all growth parameters except R:S ratio. Mycorrhizal plants had greater leaf number, leaf area, leaf dry weight, shoot and root dry weight than noncolonized seedlings. The higher P (22 ppm) level plants had superior growth compared with low P plants. Leaf area and leaf dry weight were similar in mycorrhizal/low P plants and nonmycorrhizal/high P plants. These results suggest that mycorrhizal growth enhancement has important implications for Neem trees which are found in agriculturally poor soils in hot and arid regions.
based on their mode of action or properties including: plant protection, environmental stress reduction, or plant growth enhancement. Selective treatments may be used for early season pest management to protect the seeds and seedlings from fungal and
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.
The action of foliar-applied uniconazole, paclobutrazol, dikegulac-sodium, ancymidol, 6-BA, GA4+7, and 6-BA + GA4+7 On container–grown Photinia × fraseri was studied over a one year period. Vegetative growth habit was evaluated at three month intervals. Shoot dry weight and histological examination of stern anatomy in the apical meristematic region was conducted at experiment termination.
Several plant growth regulators, primarily uniconazole, 6-BA, 6-BA + GA4+7, and dikegulac-sodium, stimulated lateral branching. Linear increases in lateral branching occurred as application rates increased. High application rates of uniconazole and paclobutrazol created an asymmetrical growth habit and decreased dry weight accumulation.
Pawpaw [Asimina triloba (L.) Dunal] is a native American fruit tree that has potential as a new fruit crop or for use in landscapes, but little information is available to nurseries on the production of containerized plants. In greenhouse experiments, growth of pawpaw seedlings in Rootrainers was examined in three fertilization regimes, two root-zone temperatures, and four substrates [ProMix, 6 pine bark: 1 sand (v/v), 1 sand: 1 sphagnum peat, and 4 pine bark: 1 sand: 1 sphagnum peat medium]. A similar germination rate of 80% was obtained in all substrates. Weekly fertigation treatments were imposed when seedlings had 2 to 3 leaves, at 0, 50, and 100 mg·L-1 N as Peters 20N-8.6P-16.6K water-soluble fertilizer plus soluble trace elements. After 140 days at the highest fertilizer rate, plant height, leaf number, and dry weight (roots, shoots, and total plant) were greater in ProMix and 1 sand:1 sphagnum peat than in 6 pine bark: 1 sand (v/v) or 4 pine bark: 1 sand: 1 sphagnum peat. Also, the root: shoot ratio was lower in ProMix and 6 pine bark: 1 sand (v/v). Overall, plant biomass production was greater in ProMix than in 6 pine bark: 1 sand (v/v). In a separate experiment, bottom heat (32 ± 0.3 °C) hastened seedling emergence from ProMix by 9 days compared to ambient root-zone conditions (24 ± 0.2 °C). An average seedling height of 10 cm was attained by ambient plants 79 days after sowing, whereas seedlings with bottom heat reached this height after 69 days. Seedlings subjected to bottom heat had increased leaf number (30%), plant height (32%), whole plant leaf area (94%), shoot dry weight (104%), root dry weight (50%), lateral root dry weight (125%), and total plant dry weight (87%). Seedlings with bottom heat had a reduction in root: shoot ratio of 25% and in specific leaf dry weight of 16% compared to ambient plants. Seedlings subjected to bottom heat had a higher leaf chlorophyll (chl) concentration of chl a (39%), chl b (33%), chl p (43%), total chl (38%), and chl a: b ratio (8%) than seedlings grown without bottom heat. Pawpaw seedling growth was best using ProMix with 100 mg·L-1 N Peters applied once weekly, or using ProMix with bottom heat and 50 mg·L-1 N Peters applied twice per week.
The horticultural Boston fern [Nephrolepis exaltata (L.) Schott cv. Verona] was micropropagated in vitro using commercial techniques. Rooted plantlets were transferred into pots containing one of three test substrates made of peat and vermiculite and subsequently inoculated with one of two species of Glomus. Survival of uninoculated control plants growing on a black peat-based mix was less than that on a brown peat-based mix. Vesicular-arbuscular mycorrhizal (VAM) inoculation significantly increased survival on the former, but not the latter, substrate. The growth of roots was enhanced in brown peatmoss, but VAM colonization was faster with black peatmoss. Compared to uninoculated controls growing under the same fertilization regime, inoculated plants had significantly higher frond P and N concentration and also showed better frond and root growth. On a growth-increment basis, our results suggested that the brown peat-based mixed was more suitable for fungal activity and fern growth.
scarce for natural growth enhancers as is information about the active components in the products, their physiological effects on plants, possible environmental effects, product stability under different environments, etc. Combining the scarce scientific
-AMF and AMF plants ( t test, P ≤ 0.05); ns = nonsignificant. Discussion In this study, dry weight of ferns and roots increased in all the AMF plants compared with non-AMF before and after Foa inoculation, which indicates the growth enhancement through
reduction in shoot growth may have contributed to root growth enhancement of tall fescue irrigated at 20% ET. A drier soil at the 0- to 25-cm depth at 20% ET irrigation in this field study also enhanced root numbers at a 36.3-cm depth, which is congruent
Bare-root Malus × domestica Borkh. seedlings were chilled for 0, 600, 1200, or 1800 hours at 5C (CH). Seedlings were then placed with roots and/or shoots in all combinations of 5 and 20C forcing conditions (FC) for up to 21 days. Virtually no growth occurred at 5C FC. When the whole plant was forced at 20C, all measures of root and shoot growth increased in magnitude, occurred earlier and at a faster rate with increasing CH. Thus, roots and shoots responded similarly to chilling. When shoots or roots were subjected to 20C FC, while the other portion of the plant was at 5C, the responses were reduced in magnitude and delayed. However, the overall growth enhancement by chilling was not negated. Root and shoot growth enhancement by chilling appeared to be increased if the other portion of the plant was actively growing also, but not dependent on it. Growth of adventitious shoots on roots (root suckers) was greatly enhanced with increasing CH on plants subjected to 5C shoot and 20C root FC. While total root and shoot bark protein levels on a per-seedling basis were similar, protein concentrations were lower in root bark than in shoot bark. During chilling, total protein per seedling generally increased until just before the time that chilling requirements for vegetative budbreak were satisfied. Protein degradation then began, resulting in lower protein levels through 2300 CH. Rapid protein breakdown (1200 to 1800 CH, roots; 1000 to 1800 CH, shoots) occurred at about the same time that root (1000 to 1800 CH) and shoot (800 to 1800 CH) growth responses to chilling were increasing. Warm FC resulted in increased protein breakdown with increased CH and forcing time.