Abstract
Abstract Soil amendments are known to promote several plant growth parameters. In many agro-ecosystems, water scarcity and drought induced phosphorus deficiency limits crop yield significantly. Considering the climate change scenario, drought and related stress factors will be even more severe endangering the global food security. Therefore, two parallel field trials were conducted to examine at what extent soil amendment of leonardite and humic acid would affect drought and phosphorus tolerance of maize. The treatments were: control (C: 100% A pan and 125 kg P ha −1 ), P deficiency (phosphorus stress (PS): 62.5 kg P ha −1 ), water deficit stress (water stress (WS): 67% A pan), and PS + WS (67% A pan and 62.5 kg P ha −1 ). Three organic amendments were (i) no amendment, (ii) 625 kg S + 750 kg leonardite ha −1 and (iii) 1250 kg S + 37.5 kg humic acid ha −1 ) tested on stress treatments. Drought and P deficiency reduced plant biomass, grain yield, chlorophyll content, F v /F m , RWC and antioxidant activity (superoxide dismutase, peroxidase, and catalase), but increased electrolyte leakage and leaf H 2 O 2 in maize plants. The combined stress of drought and P deficiency decreased further related plant traits. Humic acid and leonardite enhanced leaf P and yield in maize plants under PS. A significant increase in related parameters was observed with humic acid and leonardite under WS. The largest increase in yield and plant traits in relation to humic acid and leonardite application was observed under combined stress situation. The use of sulfur-enriched amendments can be used effectively to maintain yield of maize crop in water limited calcareous soils.
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Claims 9
Claim · model-written summary
Drought and phosphorus deficiency reduced maize biomass, grain yield and chlorophyll.
- Treatment
- Drought and P deficiencye0
- Outcome
- plant biomass, grain yield, chlorophyll contente0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Verbatim
e0“Drought and P deficiency reduced plant biomass, grain yield, chlorophyll content, F v /F m , RWC and antioxidant activity (superoxide dismutase, peroxidase, and catalase), but increased electrolyte leakage and leaf H 2 O 2 in maize plants.”
Claim · model-written summary
Drought and phosphorus deficiency reduced Fv/Fm, RWC and antioxidant activity.
- Treatment
- Drought and P deficiencye0
- Outcome
- F v /F m , RWC and antioxidant activitye0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Verbatim
e0“Drought and P deficiency reduced plant biomass, grain yield, chlorophyll content, F v /F m , RWC and antioxidant activity (superoxide dismutase, peroxidase, and catalase), but increased electrolyte leakage and leaf H 2 O 2 in maize plants.”
Claim · model-written summary
Drought and phosphorus deficiency increased electrolyte leakage and leaf hydrogen peroxide.
- Treatment
- Drought and P deficiencye0
- Outcome
- electrolyte leakage and leaf H 2 O 2e0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Verbatim
e0“Drought and P deficiency reduced plant biomass, grain yield, chlorophyll content, F v /F m , RWC and antioxidant activity (superoxide dismutase, peroxidase, and catalase), but increased electrolyte leakage and leaf H 2 O 2 in maize plants.”
Claim · model-written summary
Combined drought and phosphorus stress further decreased related plant traits.
- Treatment
- combined stress of drought and P deficiencye0
- Outcome
- related plant traitse0
- Direction
- decreasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Verbatim
e0“The combined stress of drought and P deficiency decreased further related plant traits.”
t0“maize (Zea mays L.)”
Claim · model-written summary
Humic acid enhanced maize leaf phosphorus and yield under P stress.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Verbatim
e0“Humic acid and leonardite enhanced leaf P and yield in maize plants under PS.”
Claim · model-written summary
Leonardite enhanced maize leaf phosphorus and yield under P stress.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Verbatim
e0“Humic acid and leonardite enhanced leaf P and yield in maize plants under PS.”
Claim · model-written summary
Humic acid significantly increased related parameters under water stress.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Verbatim
e0“A significant increase in related parameters was observed with humic acid and leonardite under WS.”
t0“maize (Zea mays L.)”
Claim · model-written summary
Leonardite significantly increased related parameters under water stress.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Verbatim
e0“A significant increase in related parameters was observed with humic acid and leonardite under WS.”
t0“maize (Zea mays L.)”
Claim · model-written summary
The largest yield and trait increase from amendments occurred under combined stress.
- Treatment
- humic acid and leonardite applicatione0
- Outcome
- yield and plant traitse0
- Direction
- largest increasee0
- Qualifier
- combined stress situatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Verbatim
e0“The largest increase in yield and plant traits in relation to humic acid and leonardite application was observed under combined stress situation.”
t0“maize (Zea mays L.)”
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