Regenerative Agriculture: Effects of Cover Crop and Mycorrhizal Inoculation on Salt Stress Mitigation in Floridian Tomato Cultivars

Project Overview

Project Type: On-Farm Research
Funds awarded in 2024: $29,946.00
Projected End Date: 03/31/2026
Grant Recipient: Florida International University
Region: Southern
State: Florida
Principal Investigator:
Dr. Amir Khoddamzadeh
Florida International University


No commodities identified


No practices identified

Proposal abstract:

The objective of this comprehensive investigation is to
assess and validate the effectiveness of two regenerative
agriculture (RA) methods
-specifically, the
implementation of a pigeon pea cover crop-green manure and
the inoculation with the mycorrhizal species Glomus
-in mitigating the effects of salt stress
on two distinct tomato cultivars, Solanum
cv. Tasti-Lee and Solanum
cv. Sanibel
. The rationale behind this
research is rooted in the pressing need to address the escalating
challenges posed by soil salinity in Florida, a critical
concern for tomato production.

As tomatoes represent a cornerstone of Florida's agricultural
economy, it is imperative to develop sustainable solutions that
can fortify the resilience of tomato crops against the burgeoning
threats of saline stress. The chosen cultivars, Tasti-Lee and
Sanibel, provide an intriguing comparative platform. Tasti-Lee,
renowned for its adaptability to Floridian conditions, is
anticipated to exhibit robust vigor in the face of saline
challenges. On the other hand, the relatively understudied
Sanibel variety presents an intriguing prospect, as its response
to salt stress is not well-documented. It is plausible that
Sanibel may manifest comparable or even superior growth and yield
results under saline conditions.

The innovative aspect of this proposed solution lies in
the combined treatment strategy, leveraging both the pigeon
pea cover crop-green manure and mycorrhizal inoculation
. We
hypothesize that this synergistic approach will
yield the most substantial positive impacts on the growth and
crop yield of both Tasti-Lee and Sanibel cultivars when subjected
to salt stress. If our hypothesis proves correct, this dual
application of regenerative agricultural practices would emerge
as a potent and cost-effective resource for farmers and
gardeners, regardless of the scale of their operations, who
grapple with salinity challenges in their fields.

The primary focus of our investigation is to provide empirical
evidence supporting the efficacy of these RA methods as
sustainable and practical solutions for salt-stressed tomato
cultivation. The experiment will be conducted under controlled
conditions, systematically manipulating saltwater stress levels,
and meticulously monitoring the response of each cultivar to the
designated treatments. The outcomes of this research hold the
promise of not only enhancing the salt tolerance of tomatoes but
also contributing valuable insights that can be extrapolated to
other crops facing similar challenges in saline-prone

The first RA method under scrutiny involves the
incorporation of a pigeon pea cover crop, which will serve
a dual purpose as both a cover crop and green manure. Pigeon pea
cover crops have demonstrated efficacy in weed control, nutrient
retention, and soil moisture conservation (Benedict et al., 2014;
Sharma et al., 2018). As a green manure, the cover crop can be
plowed into the soil, enriching it with organic material and
enhancing nutrient availability (Finney et al., 2017). By
investigating the impact of pigeon pea cover crop-green manure on
the two tomato cultivars, we aim to elucidate its potential role
in ameliorating salt stress and improving overall crop health and

The second RA method involves the introduction
of the mycorrhizal species Glomus intraradices to
the tomato root system. Arbuscular mycorrhizal fungi
(AMF) have been acknowledged for their positive influence on
plant health and performance under stress conditions (Ruiz-Lozano
et al., 2012; Selvakumar et al., 2014). AMF form symbiotic
relationships with plant roots, enhancing mineral acquisition and
aiding in the regulation of ion osmotic potential. By exploring
the impact of G. intraradices on the two tomato
cultivars, we seek to unravel the potential of mycorrhizal
inoculation as a targeted strategy for mitigating salt stress
effects, thereby bolstering the resilience of tomatoes to adverse
environmental conditions.

The combined application of these RA methods
aims to create a holistic and sustainable
approach to salt stress mitigation in tomato cultivation
. By
synergistically leveraging the benefits of cover cropping and
mycorrhizal inoculation, we anticipate observing enhanced plant
vigor, improved physiological responses, and ultimately increased
crop yield under saline conditions. The robustness of this dual
strategy lies in its potential to offer a comprehensive solution
that addresses multiple facets of salt stress, from soil health
to plant physiology.

The significance of this research extends beyond the laboratory,
reaching into the practical realm of agriculture. If our
hypothesis is substantiated, the proposed RA methods could emerge
as accessible and economically viable tools for farmers and
gardeners grappling with salinity challenges in their fields. The
scalability and cost-effectiveness of these methods make them
particularly appealing for both large-scale agricultural
enterprises and smaller, community-based initiatives. This aligns
with the broader goal of regenerative agriculture, which
emphasizes sustainable practices that not only enhance
productivity but also contribute to the long-term health and
resilience of agricultural ecosystems.

This research endeavors to contribute substantively to the
ongoing efforts to address the escalating challenges of salt
stress in Florida's tomato production. By focusing on the
Tasti-Lee and Sanibel cultivars and employing a dual RA approach,
we aspire to provide empirical evidence that supports the
practical implementation of these regenerative agricultural
methods. The potential benefits extend beyond the specific tomato
cultivars under investigation, with implications for the broader
agricultural landscape facing similar challenges. Ultimately,
the success of this proposed solution would mark a significant
step toward building sustainable and resilient agricultural
practices in the face of evolving environmental threats.

Project objectives from proposal:

Phase 1: Growth Chamber/Lab Component:

The initial phase of this study comprises two critical
components: Seed ecophysiology assessment under saline stress and
field crop performance under saline stress.

Seed Ecophysiology Assessment:

Seed germination and vigor tests will be conducted using three
repetitions of 50 seeds from two tomato cultivars. The seeds will
be incubated in petri dishes containing towelettes moistened with
0, 2, 4, and 6‰ NaCl solutions. Germination rates will be
recorded at 7 and 14 days, and measurements of emerging
hypocotyls and epicotyls will be obtained.

To evaluate stress-related nutrient loss, seeds will undergo
incubation with the same salinity treatments for 6 and 24 hours.
Following this, the seeds will be washed, submerged in 50 mL
distilled water, and the water medium will be tested using
nutrient ion sensors for N, P, K, Ca, and Mg concentrations,
along with electrical conductivity sensors to assess overall ion

In order to observe stress-related moisture loss, seeds will be
subjected to the petri dish method for 6 and 24 hours. Afterward,
the seeds will be weighed, dehydrated, and reweighed. The
difference in wet and dry weights will reveal seed moistures
corresponding to each salinity treatment.

Phase 2: Field Crop Component:

The field crop component involves several key steps:

  1. Soil Preparation with Green Manure:

   - Each tomato cultivar group (Tasti-Lee and Sanibel)
will undergo initial soil preparation with green manure in 120

   - Nitrogen-fixing pigeon pea (Cajanus cajan) will be
inoculated with Bradyrhizobium sp. (Pro-Mix BX Mycorrhizae,
Premier Tech, Pennsylvania, US) and grown for three months before
being mulched into the soil.

   - This will result in three soil media treatments: 4
pigeon pea plants per pot, 2 pigeon pea plants per pot, and no
pigeon pea plants per pot.

  1. Tomato Season Step:

   - Following soil preparation, the tomato season step
will commence, with tomato seeds planted for the Fall 2023

  1. Salinity Treatments:

   - Within each soil group, four sets of salinity
solutions (6‰ NaCl, 4‰ NaCl, 2‰ NaCl, and distilled water) will
be applied at five repetitions each.

  1. Mycorrhizal Inoculation:

   - Across all soil media and salinity groups, half of
the tomatoes will be inoculated with the beneficial mycorrhizal
species Glomus intraradices (Pro-Mix BX Mycorrhizae, Premier
Tech, Pennsylvania, US); the remaining half will remain

  1. Physical Leaf Measurements:

   - Leaf area changes will be measured every two

   - Histological samples for stomatal morphology will
be obtained biweekly.

   - NDVI, SPAD, and atLEAF measurements will be taken
for assessing photosynthetic activity and chlorophyll content.

Phase 3: Market and Taste Assessments:

  1. Physical Measurements of Fruits:

   - Fruit measurements will include yield per plant,
size of fruit, and firmness determined via penetrometer.

  1. Chemical Tests of Fruit Samples:

   - DPPH and FRAP assays will be conducted to assess
antioxidant content.

   - RP-HPLC and mass spectrometry readings will be
performed to quantify sugar, lycopene, and organic acid content.

  1. Chemical Testing of Pot Soil:

   - Salinity, electrical conductivity, pH, and N, P,
K, and micronutrient readings will be measured every two weeks
using laboratory pH meters and manual ionic sensors.

  1. Taste Panels:

   - Taste panels with focus groups will be organized
through the FIU Biscayne Bay campus’ Hospitality Management
program. Tomatoes will be scored based on sour and sweet flavors.

Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.