ABSTRACT
Potatoes are one of the main vegetables consumed worldwide. However, dependence on mineral fertilizers compromises producers’ profitability. New alternatives are required to increase agricultural crop yield while sustaining production. Vegetation indices have improved the agility and benefits of experimental evaluations of vegetables; however, there is a scarcity of information on potatoes. Thus, the present study aimed to assess the effectiveness of different vegetation indices for monitoring the agronomic performance of potato crops fertilized with a combination of mineral fertilizers and organic compost. The study was conducted in the municipality of Perdizes, Minas Gerais, Brazil. A randomized block design was used. Each plot was divided into five subplots that received 25 combinations of mineral and organic fertilizer treatments in four replications. Images were acquired using a remote-piloted aircraft, which generated spectral values of vegetation indices in relation to various combinations of fertilizer doses. Mineral fertilizer doses significantly correlated with the normalized green-red difference index (NGRDI), normalized difference vegetation index (NDVI), and green leaf index (GLI) at r = 0.824, 0.836, and 0.833, respectively. Even in an environment with high variability in plant growth, the NGRDI, NDVI, and GLI were significantly correlated with mineral fertilization. The agronomic performance of potato crops under various fertilizer dosages could be monitored using the obtained vegetation indices.
Key words:
Solanum tuberosum L.; sustainable production; high-performance phenotyping; organic farming
HIGHLIGHTS:
The agronomic performance of potato crops can be monitored through the use of high-throughput phenotyping.
Vegetation indices provide reliable monitoring of the nutritional status of potato crops.
The GLI, NGRDI, and NDVI indices differentiated the higher and lower productivity levels based on the fertilizer used.
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The first, second and third digits indicate: mineral fertilizer (1=0, 2=25, 3=50, 4=75, and 5=100% of 1,000 kg ha-1 monoammonium phosphate mineral fertilizer), organic compound (1=0, 2=5, 3=10, 4=15, and 5=25 t ha-1 organic compost), and the block (I=Block I, II=Block II, III=Block III, and IV=Block IV, respectively.
GLI, green leaf index; NDVI, normalized difference vegetation index; NGRDI, normalized green-red difference index. Darker (more intense) colors indicate a greater response of the vegetation index to the combination of mineral and organic fertilization. 1 - 0% mineral fertilization and 0 t ha-1 organic compost; 2 - 0% mineral fertilization and 5 t ha-1 organic compost; 3 - 0% mineral fertilization and 10 t ha-1 organic compost; 4 - 0% mineral fertilization and 15 t ha-1 organic compost; 5 - 0% mineral fertilization and 20 t ha-1 organic compost; 6 - 25% mineral fertilization and 0 t ha-1 organic compost; 7 - 25% mineral fertilization and 5 t ha-1 organic compost; 8 - 25% mineral fertilization and 10 t ha-1 organic compost; 9 - 25% mineral fertilization and 15 t ha-1 organic compost; 10 - 25% mineral fertilization and 20 t ha-1 organic compost; 11 - 50% mineral fertilization and 0 t ha-1 organic compost; 12 - 50% mineral fertilization and 5 t ha-1 organic compost; 13 - 50% mineral fertilization and 10 t ha-1 organic compost; 14 - 50% mineral fertilization and 15 t ha-1 organic compost; 15 - 50% mineral fertilization and 20 t ha-1 organic compost; 16 - 75% mineral fertilization and 0 t ha-1 organic compost; 17 - 75% mineral fertilization and 5 t ha-1 organic compost; 18 - 75% mineral fertilization and 10 t ha-1 organic compost; 19 - 75% mineral fertilization and 15 t ha-1 organic compost; 20 - 75% mineral fertilization and 20 t ha-1 organic compost; 21 - 100% mineral fertilization and 0 t ha-1 organic compost; 22 - 100% mineral fertilization and 5 t ha-1 organic compost; 23 - 100% mineral fertilization and 10 t ha-1 organic compost; 24 - 100% mineral fertilization and 15 t ha-1 organic compost; 25 - 100% mineral fertilization and 20 t ha-1 organic compost
GLI - Green leaf index; NDVI - Normalized difference vegetation index; NGRDI - Normalized green red difference index
GLI, Green leaf index; NDVI, Normalized difference vegetation index; NGRDI, Normalized green-red difference index. Red ellipse: Regions with the best relationship between the x-axis (percentage of mineral fertilization) and y-axis (vegetation index)
GLI - Green leaf index, NGRDI - Normalized green-red difference index, and NDVI - Normalized difference vegetation index
GLI, Green leaf index, NGRDI - Normalized green-red difference index, and NDVI - Normalized difference vegetation index. Blue and yellow arrows, high and low productivity (t ha-1), respectively. Means followed by the same letter do not differ from each other using the Skott-Knott test (p ≤ 0.05).