Growth, physiological and nutrient uptake traits of Crotalaria cover crops influenced by levels of carbon dioxide under low light Intensities

Authors: Baligar, Virupax; Elson, Marshall; HE, Z - University Of Florida; LI, Y - University Of Florida; PAIVA, A - Universidade Estadual De Santa Cruz; AHNERT, D - Universidade Estadual De Santa Cruz

Submitted to: International Journal of Plant Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/21/2018
Publication Date: 5/26/2018
Citation: Baligar, V.C., Elson, M.K., He, Z.L., Li, Y.C., Paiva, A.D., Ahnert, D. 2018. Growth, physiological and nutrient uptake traits of Crotalaria cover crops influenced by levels of carbon dioxide under low light Intensities. International Journal of Plant Sciences. 23(1):1-14.

Interpretive Summary: Soil erosion and leaching are the major factors for soil degradation under plantation crops such as cacao. Legume cover crops in early plantation crop establishment could reduce soil degradation by providing vegetative cover and thereby reduce soil loss by erosion. Crotalarias are tropical legumes used as cover crops or green manure crops to improve soil fertility and reduce soil degradation. As understory plants in plantation crop systems, these cover crops receive low irradiance and elevated levels of CO2 and these environmental factors could drastically affect survivability and their effectiveness as cover crops. In this paper, we report that growth parameters and essential nutrient uptake parameters of four species of important crotalaria cover crops (Short flower Rattle box, Smooth Crotalaria, Slender Leaf Rattle box, Showy Crotalaria) were significantly influenced by light intensity and levels of carbon dioxide. Among the four-crotalaria species nutrient use efficiency of Smooth Crotalaria was highest for N, Ca, Cu, and Zn, but lowest for Mn whereas, nutrient use efficiency of Showy Crotalaria was highest for P, Ca, Mg, Fe, and Mn, but lowest for N and Zn. This information will be of use to farmers in the tropics to select the appropriate type of crotalaria cover crops to reduce soil degradation and improve soil fertility and crop yields.

Technical Abstract: Technical Abstract: Crotalarias are tropical legumes grown as cover crops or green manure crops to improve soil fertility and reduce soil degradation. As understory plants in plantation crop systems, these cover crops receive low irradiance and elevated levels of CO2. A greenhouse experiment was conducted to evaluate the effects of ambient (400 µmol mol-1) and elevated (700 µmol mol-1) levels of [CO2] at low photosynthetic photon flux density (PPFD) of 100, 250 or 450 µmol m-2 s-1 on growth, physiological and nutrient use parameters of four Crotalaria species (C. breviflora, C. mucronata, C. ochroleuca and C. spectabilis). Elevated [CO2] had little effect on growth, but increased NAR and nutrient use efficiency of N, Cu, Fe and Zn. PPFD had significant effects on growth, physiology and NUE. Increasing PPFD increased nutrient use efficiency of N and K, but reduced nutrient use efficiency of P and micronutrients. At low light intensities, irrespective of [CO2], interspecies differences were observed in crotalaria for growth, physiology and nutrient uptake trats. Irrespective of [CO2] levels at low PPFD’s C. mucronata was efficient in N, Ca, Cu, and Zn use efficiency and C. spectabilis was efficient in P, Ca, Mg, Fe, and Mn use efficiency.