Abstract
Leafy vegetables are considered as the main sources of nitrate in the human diet. In order to investigate the effect of nitrate levels and harvest times on nitrate accumulation, nitrate reductase activity, concentrations of Fe, Zn, Cu and K in Lettuce and Spinach and their relation to nitrate accumulation in these leafy vegetables, two harvest times (29 and 46 days after transplanting), two vegetable species of lettuce and spinach and two concentrations of nitrate (10 and 20 mM) were used in a hydroponics greenhouse experiment with a completely randomized design and 3 replications. Modified Hoagland and Arnon nutrient solutions were used for the experiment. The results indicated that by increasing nitrate concentration of solution, nitrate accumulation in roots and shoots of lettuce and spinach increased significantly (P ≤ 0.05), and the same trend was observed for the nitrate reductase activity in the shoots of the two species. Increasing the nitrate concentrations of solution, reduced the shoot dry weight and the concentration of Fe and Cu in both species, where as it increased the K and Zn concentrations in the shoots of the two species in each both harvest times, the nitrate accumulation increased, but the nitrate reductase activity decreased in the shoots of the two species over the course of the growth. The Concentration of Fe, Cu and K decreased in the shoots of lettuce and the spinach with the time, despite the increase in Zn concentration in the shoots. The results also indicated that increasing nitrate concentrations of solution to the levels greater than the plant capacity for reduction and net uptake of nitrate, leads to the nitrate accumulation in the plants. Nitrate accumulation in plant tissue led to decreases in fresh shoot yield and Fe and Cu concentrations and nitrate reductase activities in both lettuce and spinach.
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Claims 12
Claim · model-written summary
Higher solution nitrate significantly increased root and shoot nitrate accumulation in both vegetables.
- Taxon
- lettuce and spinach
Spinacia oleracea
Lactuca sativae0 - Organ / stage
- roots and shootse0
- Treatment
- increasing nitrate concentration of solutione0
- Outcome
- nitrate accumulation in roots and shootse0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“by increasing nitrate concentration of solution, nitrate accumulation in roots and shoots of lettuce and spinach increased significantly (P ≤ 0.05)”
Claim · model-written summary
Higher nitrate increased shoot nitrate reductase activity in both species.
- Taxon
- Lettuce and SpinachSpinacia oleraceaLactuca sativat0
- Treatment
- Increasing the nitrate concentrations of solutione1
- Outcome
- nitrate reductase activity in the shootse0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the same trend was observed for the nitrate reductase activity in the shoots of the two species.”
t0“Lettuce and Spinach”
e1“Increasing the nitrate concentrations of solution, reduced the shoot dry weight and the concentration of Fe and Cu in both species”
Claim · model-written summary
Higher nitrate reduced shoot dry weight in both species.
- Taxon
- Lettuce and SpinachSpinacia oleraceaLactuca sativat0
- Treatment
- Increasing the nitrate concentrations of solutione0
- Outcome
- shoot dry weighte0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Increasing the nitrate concentrations of solution, reduced the shoot dry weight and the concentration of Fe and Cu in both species”
t0“Lettuce and Spinach”
Claim · model-written summary
Higher nitrate reduced shoot Fe and Cu concentrations in both species.
- Taxon
- Lettuce and SpinachSpinacia oleraceaLactuca sativat0
- Treatment
- Increasing the nitrate concentrations of solutione0
- Outcome
- concentration of Fe and Cue0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Increasing the nitrate concentrations of solution, reduced the shoot dry weight and the concentration of Fe and Cu in both species”
t0“Lettuce and Spinach”
Claim · model-written summary
Higher nitrate increased shoot K and Zn concentrations in both species.
- Taxon
- Lettuce and SpinachSpinacia oleraceaLactuca sativat0
- Treatment
- Increasing the nitrate concentrations of solutione1
- Outcome
- K and Zn concentrations in the shootse0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“it increased the K and Zn concentrations in the shoots of the two species”
t0“Lettuce and Spinach”
e1“Increasing the nitrate concentrations of solution, reduced the shoot dry weight and the concentration of Fe and Cu in both species”
Claim · model-written summary
Nitrate accumulation increased as the plants grew.
- Taxon
- Lettuce and SpinachSpinacia oleraceaLactuca sativat0
- Organ / stage
- course of the growthe0
- Outcome
- nitrate accumulatione0
- Direction
- increasede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the nitrate accumulation increased, but the nitrate reductase activity decreased in the shoots of the two species over the course of the growth.”
t0“Lettuce and Spinach”
Claim · model-written summary
Shoot nitrate reductase activity decreased during growth.
- Taxon
- Lettuce and SpinachSpinacia oleraceaLactuca sativat0
- Organ / stage
- course of the growthe0
- Outcome
- nitrate reductase activitye0
- Direction
- decreasede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the nitrate accumulation increased, but the nitrate reductase activity decreased in the shoots of the two species over the course of the growth.”
t0“Lettuce and Spinach”
Claim · model-written summary
Shoot Fe, Cu and K concentrations declined over time.
- Taxon
- lettuce and the spinachSpinacia oleraceaLactuca sativae0
- Organ / stage
- shootse0
- Outcome
- Concentration of Fe, Cu and Ke0
- Direction
- decreasede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The Concentration of Fe, Cu and K decreased in the shoots of lettuce and the spinach with the time”
Claim · model-written summary
Shoot Zn concentration increased over time.
- Taxon
- Lettuce and SpinachSpinacia oleraceaLactuca sativat0
- Organ / stage
- shootse0
- Outcome
- Zn concentratione0
- Direction
- increasee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“despite the increase in Zn concentration in the shoots.”
t0“Lettuce and Spinach”
Claim · model-written summary
Nitrate above plant reduction and uptake capacity caused nitrate accumulation.
- Taxon
- Lettuce and SpinachSpinacia oleraceaLactuca sativat0
- Treatment
- increasing nitrate concentrations of solutione0
- Outcome
- nitrate accumulation in the plantse0
- Direction
- increasinge0
- Qualifier
- levels greater than the plant capacity for reduction and net uptake of nitratee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“increasing nitrate concentrations of solution to the levels greater than the plant capacity for reduction and net uptake of nitrate, leads to the nitrate accumulation in the plants.”
t0“Lettuce and Spinach”
Claim · model-written summary
Nitrate accumulation was associated with lower fresh shoot yield.
- Taxon
- lettuce and spinachSpinacia oleraceaLactuca sativae0
- Outcome
- fresh shoot yielde0
- Direction
- decreasese0
- Qualifier
- Nitrate accumulation in plant tissuee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Nitrate accumulation in plant tissue led to decreases in fresh shoot yield and Fe and Cu concentrations and nitrate reductase activities in both lettuce and spinach.”
Claim · model-written summary
Nitrate accumulation was associated with lower Fe and Cu concentrations and nitrate reductase activity.
- Taxon
- lettuce and spinachSpinacia oleraceaLactuca sativae0
- Outcome
- Fe and Cu concentrations and nitrate reductase activitiese0
- Direction
- decreasese0
- Qualifier
- Nitrate accumulation in plant tissuee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Nitrate accumulation in plant tissue led to decreases in fresh shoot yield and Fe and Cu concentrations and nitrate reductase activities in both lettuce and spinach.”
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