Abstract
Rice yield has decreased due to climate variability and change in Colombia. Plant growth regulators have been used as a strategy to mitigate heat stress in different crops. Therefore, this study aimed to evaluate the effect of foliar applications of four growth regulators [auxins (AUX), brassinosteroids (BR), cytokinins (CK), or gibberellins (GA)] on physiological (stomatal conductance, total chlorophyll content, F v /F m ratio, plant canopy temperature, and relative water content) and biochemical (Malondialdehyde (MDA) and proline contents) variables in two commercial rice genotypes exposed to combined heat stress (high day and nighttime temperatures). Two separate experiments were carried out using plants of two rice genotypes, Fedearroz 67 (“F67”) and Fedearroz 2000 (“F2000”) for the first and second experiments, respectively. Both trials were analyzed together as a series of experiments. The established treatments were as follows: absolute control (AC) (rice plants grown under optimal temperatures (30/25°C day/nighttime temperatures), heat stress control (SC) [rice plants only exposed to combined heat stress (40/30°C)], and stressed rice plants and sprayed twice (5 days before and after heat stress) with a plant growth regulator (stress+AUX, stress+BR, stress+CK, or stress+GA). The results showed that foliar CK sprays enhanced the total chlorophyll content in both cultivars (3.25 and 3.65 mg g −1 fresh weight for “F67” and “F2000” rice plants, respectively) compared to SC plants (2.36 and 2.56 mg g −1 fresh weight for “F67,” and “F2000” rice plants, respectively). Foliar CK application also improved stomatal conductance mainly in “F2000” rice plants compared to their heat stress control (499.25 vs.150.60 mmol m −2 s −1 ). Foliar BR or CK sprays reduced plant canopy temperature between 2 and 3°C and MDA content in plants under heat stress. The relative tolerance index suggested that foliar CK (97.69%), and BR (60.73%) applications helped to mitigate combined heat stress mainly in “F2000” rice plants. In conclusion, foliar BR or CK applications can be considered an agronomic strategy to help to ameliorate the negative effect of combined heat stress conditions on the physiological behavior of rice plants.
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Claims 8
Claim · model-written summary
Foliar CK sprays raised total chlorophyll content of rice F67 to 3.25 mg g-1 fresh weight, above SC plants at 2.36.
- Taxon
- rice
Oryza sativae0 - Material
- F67e1
- Treatment
- foliar CK sprayse1
- Outcome
- total chlorophyll contente1
- Direction
- enhancede1
- Value
- 3.25e1
- Qualifier
- 2.36e2
- Comparator
- SC plantse2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“two commercial rice genotypes exposed to combined heat stress”
e1“foliar CK sprays enhanced the total chlorophyll content in both cultivars (3.25 and 3.65 mg g −1 fresh weight for “F67” and “F2000” rice plants, respectively)”
e2“compared to SC plants (2.36 and 2.56 mg g −1 fresh weight for “F67,” and “F2000” rice plants, respectively)”
Claim · model-written summary
Foliar CK sprays raised total chlorophyll content of rice F2000 to 3.65 mg g-1 fresh weight, above SC plants at 2.56.
- Taxon
- riceOryza sativae0
- Material
- F2000e1
- Treatment
- foliar CK sprayse1
- Outcome
- total chlorophyll contente1
- Direction
- enhancede1
- Value
- 3.65e1
- Qualifier
- 2.56e2
- Comparator
- SC plantse2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“two commercial rice genotypes exposed to combined heat stress”
e1“foliar CK sprays enhanced the total chlorophyll content in both cultivars (3.25 and 3.65 mg g −1 fresh weight for “F67” and “F2000” rice plants, respectively)”
e2“compared to SC plants (2.36 and 2.56 mg g −1 fresh weight for “F67,” and “F2000” rice plants, respectively)”
Claim · model-written summary
Foliar CK application improved stomatal conductance in rice F2000 relative to the heat stress control (499.25 vs 150.60 mmol m-2 s-1).
- Taxon
- riceOryza sativae0
- Material
- F2000e1
- Treatment
- Foliar CK applicatione1
- Outcome
- stomatal conductancee1
- Direction
- improvede1
- Value
- 499.25 vs.150.60 mmol m −2 s −1e1
- Comparator
- heat stress controle1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“two commercial rice genotypes exposed to combined heat stress”
e1“Foliar CK application also improved stomatal conductance mainly in “F2000” rice plants compared to their heat stress control (499.25 vs.150.60 mmol m −2 s −1 )”
Claim · model-written summary
Foliar BR or CK sprays reduced plant canopy temperature by 2 to 3°C under heat stress.
- Taxon
- riceOryza sativae0
- Treatment
- Foliar BR or CK sprayse1
- Outcome
- plant canopy temperaturee1
- Direction
- reducede1
- Value
- between 2 and 3°Ce1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“two commercial rice genotypes exposed to combined heat stress”
e1“Foliar BR or CK sprays reduced plant canopy temperature between 2 and 3°C and MDA content in plants under heat stress”
Claim · model-written summary
Foliar BR or CK sprays reduced MDA content in rice under heat stress.
- Taxon
- riceOryza sativae0
- Treatment
- Foliar BR or CK sprayse1
- Outcome
- MDA contente1
- Direction
- reducede1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“two commercial rice genotypes exposed to combined heat stress”
e1“Foliar BR or CK sprays reduced plant canopy temperature between 2 and 3°C and MDA content in plants under heat stress”
Claim · model-written summary
Foliar CK had a relative tolerance index of 97.69% under combined heat stress, mainly in rice F2000.
- Taxon
- riceOryza sativae0
- Material
- F2000e1
- Treatment
- foliar CKe1
- Outcome
- relative tolerance indexe1
- Direction
- helped to mitigatee1
- Value
- 97.69%e1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“two commercial rice genotypes exposed to combined heat stress”
e1“The relative tolerance index suggested that foliar CK (97.69%), and BR (60.73%) applications helped to mitigate combined heat stress mainly in “F2000” rice plants”
Claim · model-written summary
Foliar BR had a relative tolerance index of 60.73% under combined heat stress, mainly in rice F2000.
- Taxon
- riceOryza sativae0
- Material
- F2000e1
- Treatment
- BRe1
- Outcome
- relative tolerance indexe1
- Direction
- helped to mitigatee1
- Value
- 60.73%e1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“two commercial rice genotypes exposed to combined heat stress”
e1“The relative tolerance index suggested that foliar CK (97.69%), and BR (60.73%) applications helped to mitigate combined heat stress mainly in “F2000” rice plants”
Claim · model-written summary
Foliar BR or CK applications can be considered an agronomic strategy to ameliorate the negative effect of combined heat stress on rice, according to the authors.
- Taxon
- riceOryza sativae0
- Treatment
- foliar BR or CK applicationse1
- Outcome
- negative effect of combined heat stress conditionse1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“two commercial rice genotypes exposed to combined heat stress”
e1“foliar BR or CK applications can be considered an agronomic strategy to help to ameliorate the negative effect of combined heat stress conditions on the physiological behavior of rice plants”
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Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.