Use of Vegetation Activity Index for Evaluation of L-Alpha Amino Acid Treatment in Sugarcane

Accurate assessment of crop vegetative state is crucial for agricultural management, particularly under environmental stress, and detailed field experiments face logistical and cost challenges. This study addresses two key gaps: (1) limited research on the effects of biostimulants, specifically L-alpha amino acids, on sugarcane’s metabolism, yield, and quality; and (2) the need for robust, non-invasive methods to evaluate crop performance. A novel approach is proposed using the Vegetation Activity Index (VAI), derived from integrated NDVI data, as an effective tool for assessing vegetation dynamics over the crop cycle. There was no significant difference in VAI between treated and untreated areas during the plant development cycle (p = 0.342), but a significant increase in VAI was observed in treated areas post-treatment (p = 0.009). Polynomial regression models (R2: 0.921–0.959) effectively explained vegetation variability. VAI and Total Recoverable Sugars per Hectare (STH) data followed a normal distribution, with no significant difference in VAI during the plant development cycle (p = 0.342) and no significant impact on STH (p = 0.492). A strong correlation between VAI and STH for treated areas (r = 0.966, p = 0.034) was observed. The L-alpha biostimulant increased vegetation activity during critical growth periods but did not affect sugar yield. Return on investment analysis indicated high profitability for the treatment.