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Article

Light Intensity Effects on the Growth, Physiological and Nutritional Parameters of Tropical Perennial Legume Cover Crops

1
USDA-ARS-Beltsville Agricultural Research Center, Beltsville, MD 20705, USA
2
IRREC, Inst. Food and Agriculture Sci., Univ. of Florida, Fort Pierce, FL 34945, USA
3
TREC, Inst. Food and Agriculture Sci., Univ. of Florida, Homestead, FL 33031, USA
4
Dept. of Agricultural and Environmental Science, State Univ. of Santa Cruz, Ilhéus 45650-000, Brazil
5
Dept. of Biological Science, State University of Santa Cruz, Ilhéus 45650-000, Brazil
*
Author to whom correspondence should be addressed.
Agronomy 2020, 10(10), 1515; https://doi.org/10.3390/agronomy10101515
Received: 4 August 2020 / Revised: 25 September 2020 / Accepted: 3 October 2020 / Published: 6 October 2020
In the early stages of the establishment of plantation crops such as cacao, perennial legume cover crops provide vegetative cover to reduce soil and nutrient loss by erosion. Light intensity at cover crop canopy levels greatly influences their adaptability and optimum growth. As tree crops mature, understory cover crops suffer from inadequate light intensity. A greenhouse experiment was undertaken with nine perennial legume cover crop species (Calopo, Ea-Ea, Jack Bean, Lab-Lab, Mucuna ana, Mucuna preta, Cowpea, Black Pigeon Pea and Mixed Pigeon Pea) to assess the effects of three photosynthetic photon flux densities (PPFDs, µmol m−2 s−1) 180 (inadequate light), 450 (moderate light) and 900 (adequate light) on growth, physiological and nutrient uptake parameters. PPFD had highly significant effects on leaf, shoot and root growth parameters and increasing the light intensity from 180 to 900 µmol m−2 s−1 increased all growth parameters with the exception of specific leaf area. In all the legume cover crops, increasing the light intensity significantly increased the net assimilation rates (NAR), SPAD index and net photosynthesis (PN) and its components, stomatal conductance (gs), transpiration (E) and vapor pressure deficit (VPD). Cover crop species, PPFD and their interactions significantly affected water flux (Vo) and various water use efficiency parameters (WUETOTAL, WUEINST and WUEINTR). Increasing the PPFD increased the WUE in all of the cover crops. Species and PPFD had highly significant effects on the uptake of macro- and micronutrients. Overall uptakes of all nutrients were increased with increases in the PPFD from 180 to 900 µmol m−2 s−1. With few exceptions, the nutrient use efficiency (NUE) of the nutrients was significantly influenced by species, PPFD and their interactions. Except for Mn, increasing the PPFD from 180 to 900 µmol m−2 s −1 increased the NUE for all the nutrients. View Full-Text
Keywords: nutrient and water use efficiency; nutrient uptake and transport; net photosynthesis nutrient and water use efficiency; nutrient uptake and transport; net photosynthesis
MDPI and ACS Style

Baligar, V.C.; Elson, M.K.; He, Z.; Li, Y.; Paiva, A.d.Q.; Almeida, A.A.F.; Ahnert, D. Light Intensity Effects on the Growth, Physiological and Nutritional Parameters of Tropical Perennial Legume Cover Crops. Agronomy 2020, 10, 1515. https://doi.org/10.3390/agronomy10101515

AMA Style

Baligar VC, Elson MK, He Z, Li Y, Paiva AdQ, Almeida AAF, Ahnert D. Light Intensity Effects on the Growth, Physiological and Nutritional Parameters of Tropical Perennial Legume Cover Crops. Agronomy. 2020; 10(10):1515. https://doi.org/10.3390/agronomy10101515

Chicago/Turabian Style

Baligar, V. C., M. K. Elson, Z. He, Y. Li, A. d.Q. Paiva, A. A.F. Almeida, and D. Ahnert. 2020. "Light Intensity Effects on the Growth, Physiological and Nutritional Parameters of Tropical Perennial Legume Cover Crops" Agronomy 10, no. 10: 1515. https://doi.org/10.3390/agronomy10101515

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