Abstract
Drought and nitrogen availability are two important environmental factors that affect plant growth and the global distribution of plants. We examined the effect of nitrogen on PSII in the leaves of maize seedlings under drought stress using three nitrogen concentrations (0.5, 7.5 and 15mM) and three levels of water availability (normal conditions, mild drought and severe drought). Shoot fresh and dry weights and root fresh weight decreased with increasing drought conditions. In maize leaves subjected to drought stress, the chlorophyll a (Chl a) and chlorophyll b (Chl b) contents, net photosynthetic rate, transpiration rate, stomatal conductance, maximum chemical efficiency (Fv/Fm), and photochemical efficiency of PSII (ΦPSII) were significantly reduced. Moderate nitrogen supply relieved the drought stress and enhanced the photosynthetic capacity. Malondialdehyde, H2O2 and O2-• accumulated in maize leaves under drought stress. Superoxide dismutase and ascorbate peroxidase activities increased in maize leaves under mild drought stress, but were significantly reduced under severe drought stress. The NO3- content and nitrate reductase (NR) activity of maize leaves were significantly reduced under drought stress, while moderate nitrogen supply promoted the accumulation of NO3- and an increase in the nitrate reductase activity. The abscisic acid content increased significantly; this increase was positively correlated with the nitrogen concentration under drought stress. Together, these results indicate that moderate nitrogen supply increases plant resistance to drought stress, while high or low nitrogen concentrations increase the sensitivity of maize to drought stress. These findings are important for guiding the agricultural use of nitrogen fertilisers.
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Claims 11
Claim · model-written summary
Increasing drought decreased shoot and root weight.
- Treatment
- increasing drought conditionse0
- Outcome
- Shoot fresh and dry weights and root fresh weighte0
- Direction
- decreasede0
Zea maysNot reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Shoot fresh and dry weights and root fresh weight decreased with increasing drought conditions.”
t0“maize”
Claim · model-written summary
Drought reduced leaf pigments, gas exchange and PSII efficiency.
- Treatment
- drought stresse0
- Outcome
- chlorophyll a (Chl a) and chlorophyll b (Chl b) contents, net photosynthetic rate, transpiration rate, stomatal conductance, maximum chemical efficiency (Fv/Fm), and photochemical efficiency of PSII (ΦPSII)e0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In maize leaves subjected to drought stress, the chlorophyll a (Chl a) and chlorophyll b (Chl b) contents, net photosynthetic rate, transpiration rate, stomatal conductance, maximum chemical efficiency (Fv/Fm), and photochemical efficiency of PSII (ΦPSII) were significantly reduced.”
Claim · model-written summary
Moderate nitrogen relieved drought and enhanced photosynthesis.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Moderate nitrogen supply relieved the drought stress and enhanced the photosynthetic capacity.”
t0“maize”
Claim · model-written summary
Drought led to accumulation of oxidative markers.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Malondialdehyde, H2O2 and O2-• accumulated in maize leaves under drought stress.”
Claim · model-written summary
Antioxidant enzyme activity rose under mild drought.
- Treatment
- mild drought stresse0
- Outcome
- Superoxide dismutase and ascorbate peroxidase activitiese0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Superoxide dismutase and ascorbate peroxidase activities increased in maize leaves under mild drought stress”
Claim · model-written summary
Antioxidant enzyme activity fell under severe drought.
- Treatment
- severe drought stresse0
- Outcome
- Superoxide dismutase and ascorbate peroxidase activitiese1
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“were significantly reduced under severe drought stress.”
t0“maize”
e1“Superoxide dismutase and ascorbate peroxidase activities increased in maize leaves under mild drought stress”
Claim · model-written summary
Drought reduced leaf nitrate and nitrate reductase.
- Treatment
- drought stresse0
- Outcome
- NO3- content and nitrate reductase (NR) activitye0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The NO3- content and nitrate reductase (NR) activity of maize leaves were significantly reduced under drought stress”
Claim · model-written summary
Moderate nitrogen promoted nitrate accumulation and nitrate reductase activity.
- Treatment
- moderate nitrogen supplye0
- Outcome
- accumulation of NO3- and an increase in the nitrate reductase activitye0
- Direction
- increasee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“moderate nitrogen supply promoted the accumulation of NO3- and an increase in the nitrate reductase activity.”
t0“maize”
Claim · model-written summary
Abscisic acid rose and correlated positively with nitrogen under drought.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The abscisic acid content increased significantly; this increase was positively correlated with the nitrogen concentration under drought stress.”
t0“maize”
Claim · model-written summary
Moderate nitrogen improved drought resistance.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“moderate nitrogen supply increases plant resistance to drought stress”
t0“maize”
Claim · model-written summary
High or low nitrogen increased drought sensitivity.
- Treatment
- high or low nitrogen concentrationse0
- Outcome
- sensitivity of maize to drought stresse0
- Direction
- increasee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“high or low nitrogen concentrations increase the sensitivity of maize to drought stress.”
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