Abstract
When drying high moisture(450–500 g H 2 O kg −1 fw) Zea mays L. seeds, a preconditioning period of drying at low temperatures(PC) may prevent injury due to subsequent high temperature drying. We preconditioned maize seeds under four different environments(35°C / 35% RH, 35°C / 90% RH, 20°C / 35% RH, and 20°C / 90% RH) and determined the level of seed deterioration in terms of reserve stability, enzyme activity, respiration, and ultrastructural changes in the radicle meristem. During PC, respiration rates were significantly higher for the 35°C than the 20°C treatments; however, overall respiration during PC was considerably lower than during germination. After 48 h of PC, amylase activity was present in all of the PC treatments with the highest levels and additional isozymes in the 35°C / 90% RH treatment. This treatment was also the only one in which we found degradation of starch grains in the histochemical analysis. During PC, transmission electron micrographs revealed migration of lipid bodies toward the cell wall and formation of protein bodies within vacuoles. Both of these processes were more likely to appear in those treatments that allowed higher rates of desiccation or in which the seeds were more mature (Harvest 2). Mitochondrial cristae were well differentiated with no evident impairment of their integrity in any of the PC treatments. Better seed quality was obtained when seed were preconditioned at moderate (35°C) temperature and low (35%) relative humidity. We conclude from these results that the positive effects of preconditioning may occur as a balance between metabolic and morphological processes resulting in high temperature desiccation tolerance, while minimizing the negative impact of the catabolic events such as degradation of starch grains and higher respiration rates.
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Claims 11
Claim · model-written summary
Maize seed respiration during preconditioning was significantly higher at 35°C than at 20°C.
Zea maysOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“During PC, respiration rates were significantly higher for the 35°C than the 20°C treatments”
t0“Maize”
Claim · model-written summary
Overall maize seed respiration during preconditioning was lower than during germination.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“overall respiration during PC was considerably lower than during germination.”
t0“Maize”
Claim · model-written summary
Amylase activity was present after 48 hours under all maize seed preconditioning treatments.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“After 48 h of PC, amylase activity was present in all of the PC treatments”
t0“Maize”
Claim · model-written summary
The 35°C and 90% RH treatment produced the highest amylase levels and additional isozymes.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“After 48 h of PC, amylase activity was present in all of the PC treatments with the highest levels and additional isozymes in the 35°C / 90% RH treatment.”
t0“Maize”
Claim · model-written summary
Starch grains degraded only in maize seeds treated at 35°C and 90% RH.
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“After 48 h of PC, amylase activity was present in all of the PC treatments with the highest levels and additional isozymes in the 35°C / 90% RH treatment. This treatment was also the only one in which we found degradation of starch grains in the histochemical analysis.”
t0“Maize”
Claim · model-written summary
During preconditioning, lipid bodies migrated toward the cell wall in maize radicle cells.
- Outcome
- migration of lipid bodies toward the cell walle0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“During PC, transmission electron micrographs revealed migration of lipid bodies toward the cell wall”
t0“Maize”
Claim · model-written summary
During preconditioning, protein bodies formed within vacuoles in maize radicle cells.
- Outcome
- formation of protein bodies within vacuolese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“formation of protein bodies within vacuoles.”
t0“Maize”
Claim · model-written summary
Lipid migration and protein body formation were more likely with faster desiccation or more mature maize seed.
- Treatment
- higher rates of desiccatione0
- Outcome
- Both of these processese0
- Direction
- more likelye0
- Qualifier
- Harvest 2e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Both of these processes were more likely to appear in those treatments that allowed higher rates of desiccation or in which the seeds were more mature (Harvest 2).”
t0“Maize”
Claim · model-written summary
Mitochondrial cristae remained well differentiated and intact in all maize seed preconditioning treatments.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Mitochondrial cristae were well differentiated with no evident impairment of their integrity in any of the PC treatments.”
t0“Maize”
Claim · model-written summary
Maize seed quality was better after preconditioning at 35°C and 35% relative humidity.
- Treatment
- moderate (35°C) temperature and low (35%) relative humiditye0
- Outcome
- seed qualitye0
- Direction
- Bettere0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Better seed quality was obtained when seed were preconditioned at moderate (35°C) temperature and low (35%) relative humidity.”
t0“Maize”
Claim · model-written summary
The authors attribute beneficial preconditioning to a balance of metabolic and morphological processes that enables high-temperature drying tolerance.
- Outcome
- high temperature desiccation tolerancee0
- Qualifier
- balance between metabolic and morphological processese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the positive effects of preconditioning may occur as a balance between metabolic and morphological processes resulting in high temperature desiccation tolerance, while minimizing the negative impact of the catabolic events such as degradation of starch grains and higher respiration rates.”
t0“Maize”
The same questions in other papers
humidity · quality: grain · Zea mays (maize)Positive and negative results
1 reporting no difference from an alternative
- no effect
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.