Source: UNIV OF HAWAII submitted to
UTILIZATION OF ARBUSCULAR MYCORRHIZAL FUNGI FOR ENVIRONMENTALLY SOUND PRODUCTION OF VEGETABLE CROPS
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
TERMINATED
Funding Source
Reporting Frequency
Annual
Accession No.
0194054
Grant No.
(N/A)
Project No.
HAW00845-H
Proposal No.
(N/A)
Multistate No.
(N/A)
Program Code
(N/A)
Project Start Date
Oct 1, 2002
Project End Date
Sep 30, 2006
Grant Year
(N/A)
Project Director
Habte, D.
Recipient Organization
UNIV OF HAWAII
3190 MAILE WAY
HONOLULU,HI 96822
Performing Department
TROPICAL PLANT & SOIL SCIENCE
Non Technical Summary
The uncontrolled development of algae, cyanobacteria and aquatic plants due to non-point source pollution of P from agriculture is of particular concern to coastal states like Hawaii. The purpose of this study is to better understand the interaction of arbuscular mycorrhizal fungi with vegetable crops in order to provide the crops with adequate P while minimizing the adverse effects of P on the environment.
Animal Health Component
60%
Research Effort Categories
Basic
30%
Applied
60%
Developmental
10%
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
1021499102030%
1021499107050%
1021499110220%
Goals / Objectives
1) Identify AMF isolates that express high level of symbiotic effectiveness on a wide variety of vegetable crops across soil types commonly used for growing vegetable crops in Hawaii. 2) Characterize the mycorrhizal dependency of vegetable crops commonly grown in Hawaii. 3) Evaluate protocols developed for mycorrhization of tree seedlings for adaptability to vegetable crop seedlings. 4) Determine the impact of cropping sequence on the abundance and symbiotic efficacy of AMF on target vegetable crops. 5) Demonstrate to vegetable growers and extension agents the impacts of arbuscular mycorrhizal fungi on the health and productivity of vegetable crops.
Project Methods
Soils will be optimized for arbuscular mycorrhizal fungal (AMF) activity and different isolates of AMF will be evaluated at comparable inoculum potentials for their effectiveness in enhancing nutrient uptake and growth of vegetable crops. Peat based media optimized with slow realize or rapid-release fertilizers at concentrations previously proven to be useful for raising mycorrhizal tree seedlings will be evaluated for usefulness for raising mycorrhizal seedlings of vegetable crops. To determine the mycorrhizal dependency of vegetable crops, plant species will be grown in the presence or absence of AMF at soil solution P concentrations ranging from 0.002 to 0.2 mg/l. Mycorrhizal dependency categories of vegetable crop species will be determined using procedures previously developed by the PI. Poorly mycorrhizal, inherently non-mycorrhizal, and highly mycorrhizal vegetable crop species will be grown for different durations in different sequence permutations in soil optimized for mycorrhizal host growth. The impacts of cropping sequence on the mycorrhizal-dependent growth of an indicator vegetable crop and on the population AMF propagules in soil will be determined. Midway in the life of the project, demonstration plots will be established on farmer land and on the Waimanalo Experimental Station for the purpose of familiarizing growers with the AMF technology. This will be achieved by growing selected vegetable crops in the presence or absence of AMF on the established plots. Growers will be taken to the site to observe the impact of AMF on vegetable crops. Technical assistance will be provided to those who would like to integrate the technology into their farm operation.

Progress 10/01/02 to 09/30/06

Outputs
One of the variables that is critical in determining whetehr or not to apply the arbuscular mycorrhizal technology in vegetable crop production is the degree to which vegetable crops of interest rely on the mycorrhizal condition for nutrient uptake and growth. During the life of the project, we have determined the AM dependency of a number of vegetable crops. These include aparagus, bell pepper, egg plant, onion,tomato, and sunflower. Asparagus and onion were classified as highly dependent speices while egg plant, sunflower, and tomato were classified as marginally dependent. The study on bell pepper was aborted because of disease infestation. We observed that crops that are different in their dpependence on the mycorrhizal condition required different mycorrhization media in the nursery. Mycorrhization of onion seedlings in the nursery led to a three-fold increase in on- ion bulb and foliage yield after transplanting in the field. Research we undertook also showed that vegetable crop speiceis like ginger that cannot be inoculated at the time of planting could be inoculated through a companion crop like onion after the former plants were established in the field. In another study, in which we evaluated the influene of cropping sequence on the effectiveness of AM fungal effectiveness in onion, we found out that growth and P status of onion was stimulated by a previous crop of sun hemp to a greater extent than by a previous crop of mustard. However, the effect of AM fungal inoculation was initially negative although the effect disappeared as time progressed. This was explainable by the fact that initially onion was allowing its roots to be colonized by AM fungi at soil solution P concentrations which were near-sufficient for mycorrhiza-free growth. Arbuscular mycorrhizal colonization of onion roots was somewhat higher if onion was preceded by sun hemp than by mustard, but the values were not statistically significant. Leaf P content monitored as a function of time also indicated that there was no mycorrhizal inoculation effect. However, P content of onion was significantly higer if sun hemp was the previous crop than if mustard was the previous crop. In either case, the level of AM fungal colonization of roots declined with time irrespective of the mycorrhizal status of onion at the time of transplanting. As a result, final bulb and leaf yield of onion was not affected by mycorrhizal inoculation. These observations suggest that the ephemral nature of the parasitic effect of AM fungi observed was due to the fact that onion was subsequently suppressing the development of the fungi in its roots under the prevailing circumstances.

Impacts
As a result of our study,we have made available a method for raising robust mycorrhizal seedlings of vegetable crops in the nursery and has further demonstrated that a judicious application of the AM technology in vegetable crop production can nealry tripple yield as illustrated in onion while reducing the amount of P added to soil by as much as 20-fold, conservativally speaking. Our work also demonstrated for the first time under field condtion that while AM fungi can act as parasites on associated plants, this effect is short-lived and may not influence final yield significantly.Our results point to the importance of considering previous cropping history,soil solution P status, and mycorrhhizal dependence of host species when growers are contemplating the application of arbuscular mycorrhizal technology in their cropping systems.

Publications

  • I. Kawamoto and M. Habte. 2006. Enhancement of arbuscular mycorrhizal status of an established ginger crop through the introduction of a companion onion crop.Fifth International Conference on Mycorrhiza, Granada, Spain. Abstract.


Progress 10/01/04 to 09/30/05

Outputs
In long-term vegetable crops such as ginger which are propagated by vegetative means the incorporation of the arbuscular mycorrhizal technology faces a challenge since a substantial amount of time elapses before root development from cuttings, and roots are the targets for arbuscular mycorrhizal fungal colonization. One approach of overcoming this constraint was evaluated. It involved introducing arbuscular mycorrhizal fungi through the agency of a mycorrhizal companion crop like onion. For this purpose, we established mycorrhizal fungi on roots of onion and planted the mycorrhizal seedlings adjacent to established ginger plants in the field. The practice enabled us to successfully transfer mycorrhizal colonization levels in ginger roots and the onion crop had no adverse effect on ginger yield. In another field experiment, we grew mycorrhizal and nonmycorrhizal onion seedlings in the field using adjacent plots inherently differing in soil solution phosphorus. In one of the fields, mycorrhizal colonization led to early yield depression while no such effect was noted in the other field. This negative effect of arbuscular mycorrhizal colonization subsequently disappeared. Final harvest of fresh and dry total biomass and onion bulb yields did not respond to mycorrhizal inoculation. The soils had an initial P concentration of 0.07 and 0.134 mg/l. Examination of the symbiotic efficacy of the populations of the indigenous AMF indicated that they were effective. Apparently the soil P concentrations were high enough to inhibit the symbiotic activity of indigenous as well as the introduced AMF species.

Impacts
We have developed an approach that will enable ginger growers to conveniently integrate arbuscular mycorrhizal fungi in their production schemes. Data we generated during this fiscal year in combination with data we generated earlier will help the farmer determine under what soil solution P concentrations the grower should and should not consider applying the mycorrhizal technology in his/her production schemes.

Publications

  • No publications reported this period


Progress 10/01/03 to 09/30/04

Outputs
The approaches we needed to develop in order to produce robust seedlings of vegetable crops colonized by mycorrhizal fungi are now near completion. We noted that one mycorrhization medium will not work for all vegetable crops because of the variation among the crops with respect to their mycorrhizal dependency. Species of vegetable crops that were marginally to moderately dependent on the mycorrhizal condition for growth and nutrient uptake were poorly colonized by arbuscular mycorrhizal fungi if they were grown on medium suited for mycorrhization of highly to very highly mycorrhiza-dependent species. These differences could be narrowed appreciably if the nutrient levels needed for maximal growth were added after roots were colonized by arbuscular mycorrhizal fungi. We also determined the mycorrhizal dependency of tomato, eggplant, onion, bell pepper and asparagus during this reporting period. Onion and asparagus were found to be highly dependent while tomato and eggplant were classified as marginally dependent. The usefulness of the mycorrhization medium developed for highly dependent mycorrhizal vegetable crop species was evaluated by comparing mycorrhizal and nonmycorrhizal onion seedlings in the field. The results showed that the fresh biomass yield of mycorrhizal seedlings was nearly double that of nonmycorrhizal ones.

Impacts
The results of our report suggest that growers can nearly double onion yields in their field at very low concentrations of phosphorus if they choose to apply the arbuscular mycorrhizal (AM) technology prescribed by the results of our study. In the absence of AM fungi, they will conservatively require 40 times as much phosphorus as that needed to grow the plants in the presence of the fungi.

Publications

  • No publications reported this period


Progress 10/01/02 to 09/30/03

Outputs
We acquired six different arbuscular mycorrhizal fungal isolates, seeds of several species of vegetable crops, and purchased various types of plastic trays needed for the project. We evaluated the usefulness of mycorrhization procedures developed for tree species for adaptability in the production of mycorrhizal seedlings. While the procedures could be useful for the mycorrhization of some vegetable crops, they were unsatisfactory for others. A series of experiments were carried out to modify the procedures with the intent of making them useful for the mycorrhization of all vegetable crop species. The preliminary results obtained thus far show that we are on our way to meeting this objective.

Impacts
If the preliminary data we obtained are confirmed by subsequent experimentation, the method will help growers produce robust vegetable crop seedlings well colonized by mycorrhizal fungi. This will overcome a major obstacle to the application of the mycorrhizal technology in sustainable vegetable crop production in Hawaii.

Publications

  • No publications reported this period


Progress 10/01/01 to 09/30/02

Outputs
No progress to report. This project was initiated on October 1, 2002.

Impacts
(N/A)

Publications

  • No publications reported this period