Articles
Nitrogen gradient effects on cacao biomass
Article number
1432_22
Pages
159 – 164
Language
English
Abstract
This study aims to assist nitrogen (N) management in cacao cultivation through an extensive greenhouse trial.
Recognizing the crucial role of N in plant growth and the environmental and economic implications of its use, we examined the biomass response of cacao (Theobroma cacao L.) trees to four N application levels: 0, 20, 60, and 100% adjustments of Hoagland’s nutrient solution.
The treatments consisted of 0, 3.1, 9.3, and 15.5 mM N, respectively.
We hypothesized a positive yet nonlinear response to N application, with an anticipated efficiency plateau beyond which additional N would not proportionally enhance growth.
Our results indicated that leaf N content was significantly higher in the upper canopy of the 100% N treatment, with the EET-94 genotype at 100% N (EN100) exhibiting the highest N content.
No maternal genotype differences were present in the lower canopy of the 100% N treatment or any of the 20% N treatments.
Trunk diameter growth rates, measured manually and with dendrometers, were significantly influenced by N levels, with higher N correlating with increased trunk growth rates.
Total biomass weight positively correlated with N levels, with significantly lower biomass at 0 and 20% N treatments.
The 60% N treatment resulted in a marked increase in biomass, but the 100% treatment did not significantly exceed the 60% level.
Aboveground biomass (leaves and stems) showed significant increases with higher N levels, whereas root biomass varied less, likely due to pot size limitations.
These results reinforce the importance of N in cacao nutrition by capturing tree nutrient and growth status during the experiment and total tree biomass at the end of the study period.
Leveraging control greenhouse conditions facilitates fundamental discovery of mineral nutrition of cacao compared to tree crops grown in the field.
Identifying this optimal application rate is critical for balancing growth benefits with environmental and economic considerations.
Recognizing the crucial role of N in plant growth and the environmental and economic implications of its use, we examined the biomass response of cacao (Theobroma cacao L.) trees to four N application levels: 0, 20, 60, and 100% adjustments of Hoagland’s nutrient solution.
The treatments consisted of 0, 3.1, 9.3, and 15.5 mM N, respectively.
We hypothesized a positive yet nonlinear response to N application, with an anticipated efficiency plateau beyond which additional N would not proportionally enhance growth.
Our results indicated that leaf N content was significantly higher in the upper canopy of the 100% N treatment, with the EET-94 genotype at 100% N (EN100) exhibiting the highest N content.
No maternal genotype differences were present in the lower canopy of the 100% N treatment or any of the 20% N treatments.
Trunk diameter growth rates, measured manually and with dendrometers, were significantly influenced by N levels, with higher N correlating with increased trunk growth rates.
Total biomass weight positively correlated with N levels, with significantly lower biomass at 0 and 20% N treatments.
The 60% N treatment resulted in a marked increase in biomass, but the 100% treatment did not significantly exceed the 60% level.
Aboveground biomass (leaves and stems) showed significant increases with higher N levels, whereas root biomass varied less, likely due to pot size limitations.
These results reinforce the importance of N in cacao nutrition by capturing tree nutrient and growth status during the experiment and total tree biomass at the end of the study period.
Leveraging control greenhouse conditions facilitates fundamental discovery of mineral nutrition of cacao compared to tree crops grown in the field.
Identifying this optimal application rate is critical for balancing growth benefits with environmental and economic considerations.
Authors
I. Martinez, S. Kassama, S.D.S. Khalsa
Keywords
N, cacao, biomass, California, greenhouse
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