Abstract
Abstract Although the tropical grasses are very productive in Hawaii and elsewhere, their production at subtropical latitudes or elevations is often limited by seasonally low‐temperatures. The feasibility of overcoming low‐temperature effects by applying gibberellic acid (GA 3 ) was therefore evaluated over a 4‐year period on swards of kikuyugrass ( Pennisetum clandestinum Hochst. ex. Chiov.) at two sites and pangola digitgrass ( Digitaria decumbens Stent) at one site. Significant responses to 62 g GA/ha were obtained in all experiments over the range of N‐fertilization tested (68–180 kg N/ha). Over a 4‐year period, the average response of kikuyugrass to GA under a clipping regime was 1260 kg dry matter (DM)/ha. The average response to ammonium sulfate (at N rates ≥ 68 kg/ha) was 15 kg DM/kg N. Average pangola responses were 1450 kg DM/ha from GA treatment and 10.5 kg DM/kg N. In some cases, the GA responses could not be duplicated by higher levels of N fertilization. GA applied on the date of clipping was as effective as GA applied 2 weeks later, but under some conditions, GA was less effective in increasing (DM) production once regrowth entered the boom portion of the regrowth curve. Growth retardation subsequent to the GA response occurred in clipped plots but not in plots which were left unclipped or were defoliated by 2 weeks of grazing. GA treatment appears to be feasible for increasing production of kikuyugrass and pangola during the cool season. The responses were enhanced by a moderate level of N‐fertilization, and the full‐season responses from single applications of GA were better under grazing than under clipping. The GA‐treated forage was stemmier and thus less completely consumed by grazing animals, however.
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Claims 13
Claim · model-written summary
Kikuyugrass responded significantly to 62 g GA/ha across tested nitrogen rates.
- Taxon
- kikuyugrass
Cenchrus flacciduse1 - Treatment
- 62 g GA/hae0
- Outcome
- responsese0
- Qualifier
- 68–180 kg N/hae0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Significant responses to 62 g GA/ha were obtained in all experiments over the range of N‐fertilization tested (68–180 kg N/ha).”
e1“kikuyugrass ( Pennisetum clandestinum Hochst. ex. Chiov.)”
Claim · model-written summary
Kikuyugrass gained an average 1260 kg dry matter per hectare from GA under clipping.
- Taxon
- kikuyugrassCenchrus flacciduse0
- Treatment
- GAe0
- Outcome
- average responsee0
- Value
- 1260 kg dry matter (DM)/hae0
- Qualifier
- under a clipping regimee0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the average response of kikuyugrass to GA under a clipping regime was 1260 kg dry matter (DM)/ha”
Claim · model-written summary
Kikuyugrass averaged 15 kg DM/kg N in response to ammonium sulfate.
- Taxon
- kikuyugrassCenchrus flacciduse1
- Treatment
- ammonium sulfatee0
- Outcome
- average responsee0
- Value
- 15 kg DM/kg Ne0
- Qualifier
- N rates ≥ 68 kg/hae0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The average response to ammonium sulfate (at N rates ≥ 68 kg/ha) was 15 kg DM/kg N.”
e1“kikuyugrass to GA under a clipping regime”
Claim · model-written summary
Pangola digitgrass averaged 1450 kg DM/ha response to GA.
Not reportedComparatorDirection
Verbatim
e0“Average pangola responses were 1450 kg DM/ha from GA treatment and 10.5 kg DM/kg N.”
e1“pangola digitgrass ( Digitaria decumbens Stent)”
Claim · model-written summary
Pangola digitgrass averaged 10.5 kg DM/kg N response to nitrogen.
Not reportedComparatorDirection
Verbatim
e0“Average pangola responses were 1450 kg DM/ha from GA treatment and 10.5 kg DM/kg N.”
e1“pangola digitgrass ( Digitaria decumbens Stent)”
Claim · model-written summary
Higher nitrogen fertilization sometimes failed to duplicate GA responses.
- Taxon
- kikuyugrassCenchrus flacciduse1
- Treatment
- GAe0
- Outcome
- GA responsese0
- Qualifier
- In some casese0
- Comparator
- higher levels of N fertilizatione0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In some cases, the GA responses could not be duplicated by higher levels of N fertilization.”
e1“kikuyugrass ( Pennisetum clandestinum Hochst. ex. Chiov.)”
Claim · model-written summary
GA applied at clipping was as effective as application two weeks later.
- Taxon
- kikuyugrassCenchrus flacciduse1
- Treatment
- GA applied on the date of clippinge0
- Outcome
- as effectivee0
- Direction
- as effectivee0
- Comparator
- GA applied 2 weeks latere0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“GA applied on the date of clipping was as effective as GA applied 2 weeks later”
e1“kikuyugrass ( Pennisetum clandestinum Hochst. ex. Chiov.)”
Claim · model-written summary
GA was sometimes less effective at increasing dry matter after regrowth reached the boom portion.
- Taxon
- kikuyugrassCenchrus flacciduse1
- Treatment
- GAe0
- Outcome
- (DM) productione0
- Direction
- less effectivee0
- Qualifier
- once regrowth entered the boom portion of the regrowth curvee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“under some conditions, GA was less effective in increasing (DM) production once regrowth entered the boom portion of the regrowth curve”
e1“kikuyugrass ( Pennisetum clandestinum Hochst. ex. Chiov.)”
Claim · model-written summary
After GA response, clipped plots had growth retardation.
- Taxon
- kikuyugrassCenchrus flacciduse1
- Treatment
- clipped plotse0
- Outcome
- Growth retardatione0
- Comparator
- plots which were left unclipped or were defoliated by 2 weeks of grazinge0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Growth retardation subsequent to the GA response occurred in clipped plots but not in plots which were left unclipped or were defoliated by 2 weeks of grazing.”
e1“kikuyugrass ( Pennisetum clandestinum Hochst. ex. Chiov.)”
Claim · model-written summary
Moderate nitrogen fertilization enhanced GA responses.
- Taxon
- kikuyugrass and pangolae1
- Treatment
- moderate level of N‐fertilizatione0
- Outcome
- responsese0
- Direction
- enhancede0
Not reportedComparator
Verbatim
e0“The responses were enhanced by a moderate level of N‐fertilization”
e1“kikuyugrass and pangola during the cool season”
Claim · model-written summary
GA single-application full-season responses were better with grazing than clipping.
Verbatim
e0“the full‐season responses from single applications of GA were better under grazing than under clipping”
e1“kikuyugrass and pangola during the cool season”
Claim · model-written summary
GA-treated forage was stemmier and less completely consumed by grazing animals.
- Taxon
- kikuyugrass and pangolae1
- Treatment
- GA‐treatede0
- Outcome
- stemmier and thus less completely consumed by grazing animalse0
- Direction
- less completelye0
Not reportedComparator
Verbatim
e0“The GA‐treated forage was stemmier and thus less completely consumed by grazing animals”
e1“kikuyugrass and pangola during the cool season”
Claim · model-written summary
The authors conclude GA treatment is feasible for raising cool-season production.
Verbatim
e0“GA treatment appears to be feasible for increasing production of kikuyugrass and pangola during the cool season”
The same questions in other papers
Gibberellic acid · growth · Cenchrus flaccidus (kikuyugrass)Positive and negative results
1 in the opposite direction
- positive
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.