Abstract
This study examined the effect of irrigation rates, nitrogen (N) fertilizer rates, and methods of applying N on growth and productivity of young (3 to 5 years old) and maturing (8 to 10 years old) citrus trees. A long-term study was conducted with the following objectives: 1) to measure the main effects of N rate, N application method, and irrigation on citrus tree growth and production from planting to maturity; 2) to establish growth and production relationships for long-term N rates and irrigation on well-drained sandy Entisols; and 3) to determine the effect of split fertilizer applications at two soil moisture regimes on citrus growth and production for two tree age classes as trees mature. Irrigation was applied using two selected ranges of soil moisture tensions and annual N rate varied by tree age as percentages of recommended. Methods of applying N included a dry granular fertilizer (DGF) containing soluble N applied four times annually or a controlled-release fertilizer (CRF) applied once per year and fertigation applied either four (FG04) or 30 (FG30) times annually. Canopy size and yield were higher with the moderate irrigation rate compared with the low rate for both young and maturing trees. Critical N rates for both canopy volume and yield were between 178 and 200 kg·ha −1 . The CRF and FG30 treatments produced larger trees and higher yields compared with FG04 and DGF in the young tree study, indicating that younger trees benefitted from frequent split fertilizer applications. As the trees matured and filled their allocated space, the two irrigation rates were continued and N was applied at six rates using either DGF or FG30. For these 8- to 10-year-old trees, critical values of N application rates were 210 and 204 kg·ha −1 for DGF and FG30, respectively. The absence of a significant interaction between N rate and application method indicated that N uptake efficiency was similar for all application methods tested. DGF and FG30 treatments resulted in similar maturing tree yields and fruit total soluble solids. Canopy volumes, for the same trees, were significantly greater all 3 years with the FG30 treatment compared with DGF. Thus, if increase in tree size is desired, increased number of split applications will likely promote tree growth; however, little increase in fruit yield may be obtained.
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Claims 14
Claim · model-written summary
Moderate irrigation produced larger canopies than low irrigation in young and maturing citrus trees.
CitrusOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Canopy size and yield were higher with the moderate irrigation rate compared with the low rate for both young and maturing trees”
t0“Citrus Trees”
Claim · model-written summary
Moderate irrigation produced higher yield than low irrigation in young and maturing citrus trees.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Canopy size and yield were higher with the moderate irrigation rate compared with the low rate for both young and maturing trees”
t0“Citrus Trees”
Claim · model-written summary
Critical nitrogen rates for canopy volume and yield were between 178 and 200 kg·ha −1.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Critical N rates for both canopy volume and yield were between 178 and 200 kg·ha −1”
t0“Citrus Trees”
Claim · model-written summary
CRF produced larger young trees and higher yields than FG04 and DGF.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The CRF and FG30 treatments produced larger trees and higher yields compared with FG04 and DGF in the young tree study”
t0“Citrus Trees”
Claim · model-written summary
FG30 produced larger young trees and higher yields than FG04 and DGF.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The CRF and FG30 treatments produced larger trees and higher yields compared with FG04 and DGF in the young tree study”
t0“Citrus Trees”
Claim · model-written summary
The critical nitrogen application rate for maturing trees with DGF was 210 kg·ha −1.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“critical values of N application rates were 210 and 204 kg·ha −1 for DGF and FG30, respectively”
t0“Citrus Trees”
Claim · model-written summary
The critical nitrogen application rate for maturing trees with FG30 was 204 kg·ha −1.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“critical values of N application rates were 210 and 204 kg·ha −1 for DGF and FG30, respectively”
t0“Citrus Trees”
Claim · model-written summary
Nitrogen rate and application method had no significant interaction.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The absence of a significant interaction between N rate and application method indicated that N uptake efficiency was similar for all application methods tested”
t0“Citrus Trees”
Claim · model-written summary
Nitrogen uptake efficiency was similar across tested application methods.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“N uptake efficiency was similar for all application methods tested”
t0“Citrus Trees”
Claim · model-written summary
DGF and FG30 produced similar yields in maturing trees.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“DGF and FG30 treatments resulted in similar maturing tree yields and fruit total soluble solids”
t0“Citrus Trees”
Claim · model-written summary
DGF and FG30 produced similar fruit total soluble solids in maturing trees.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“DGF and FG30 treatments resulted in similar maturing tree yields and fruit total soluble solids”
t0“Citrus Trees”
Claim · model-written summary
FG30 produced significantly greater canopy volumes than DGF in all three years.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Canopy volumes, for the same trees, were significantly greater all 3 years with the FG30 treatment compared with DGF”
t0“Citrus Trees”
Claim · model-written summary
More split applications are likely to promote tree growth when larger trees are desired.
- Outcome
- increased number of split applications will likely promote tree growthe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“if increase in tree size is desired, increased number of split applications will likely promote tree growth”
t0“Citrus Trees”
Claim · model-written summary
More split applications may yield little increase in fruit yield.
- Outcome
- little increase in fruit yield may be obtainede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“little increase in fruit yield may be obtained”
t0“Citrus Trees”
The same questions in other papers
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See all 26 papers →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.