Estimating Nitrogen and Chlorophyll Status of Romaine Lettuce using SPAD and atLEAF readings

8/20/2019 7:52:12 AM

Notulae Botanicae Horti Agrobotanici Cluj-Napoca Vol 47 No 3 (2019) & 6, 2019

R O MENDOZA-TAFOLLA1, P JUAREZ-LOPEZ1, R E ONTIVEROS-CAPURATA2, M SANDOVAL-VILLA3, I ALIA-TEJACAL1, G ALEJO-SANTIAGO4 1 Universidad Autonoma del Estado de Morelos, Posgrado en Ciencias Agropecuarias y Desarrollo Rural, Facultad de Ciencias Agropecuarias, Av. Universidad 1001, 62209 Cuernavaca, Morelos ;2 Catedra CONACYT- Instituto Mexicano de Tecnologia del Agua, Paseo Cuauhnahuac 8532, 62550 Jiutepec, Morelos; 3 Colegio de Postgraduados, Edafologia, Campus Montecillo 56230, Montecillo, Estado de Mexico; 4 Universidad Autónoma de Nayarit, Unidad Academica de Agricultura, Carretera Tepic-Compostela Km. 9, 63780, Xalisco, Nayarit

Nitrogen (N) is an essential nutrient for plant growth and development and is especially important in the production of high quality leafy green vegetables. In this experiment, leaf N concentration, chlorophyll concentration (Chl) and weight above fresh matter (AFM) of romaine lettuce (Lactuca sativa L. var. longifolia) were estimated by correlations between in situ SPAD and atLEAF readings. Lettuce was grown in high tunnels during 42 days and was irrigated at five nitrogen levels: 0, 4, 8, 12 and 16 mEq·L-1 of NO3-, based on the Steiner nutrient solution. The N concentration, Chl concentration and AFM were determined in the laboratory, while SPAD and atLEAF readings were measured in situ weekly. SPAD readings had high, positive and significant linear correlations with N (R2 = 0.90), Chl (R2 = 0.97) and AFM (R2 = 0.98); atLEAF readings had a similar linear correlation with N (R2 = 0.91), Chl (R2 = 0.92) and AFM (R2 = 0.97). Besides, SPAD and atLEAF readings had high, positive, and significant linear correlation (R2 = 0.96). Thus, SPAD and atLEAF meters can be used to non-destructively and accurately estimate the N status of lettuce, in a reliable and quick manner during the crop production cycle. In addition, atLEAF is currently more affordable than SPAD.

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