###### Abstract  
Taro (_Colocasia esculenta_ ([PERSON]) and sweet potato (_Ipomoea batatas_ ([PERSON]) are important food crops worldwide, whose productivity is threatened by climatic constraints, namely drought. Data calibration, validation, and model development of high-precision near-infrared spectroscopy (NIRS) involving multivariate analyses are needed for the fast prediction of the quality of tubers and shoots impacted by drought stress. The main objective of this study was to generate accurate NIRS models for quality assessment of taro and sweet potato accessions (acc.) subjected to water scarcity conditions. Seven taro and eight sweet potato acc. from diverse geographical origins were evaluated for nitrogen (N), protein (Pt), starch (St), total mineral (M), calcium oxalate (CaOx), carbon isotope discrimination (\(\Delta^{13}\)C), and nitrogen isotopic composition (\(\delta^{15}\)N). Models were developed separately for both crops underground and aboveground organs. N, Pt, St, and M models could be used as quality control constituents, with a determination coefficient of prediction (\(\text{r}^{2}_{\text{pred}}\)) between 0.856 and 0.995. \(\delta^{13}\)C, \(\delta^{15}\)N, and CaOx, with \(\text{r}^{2}_{\text{pred}}\) between 0.178 and 0.788, could be used as an informative germplasm screening tool. The approach used in the present study demonstrates NIRS's potential for further research on crop quality under drought. calcium oxalate; carbon and nitrogen isotopic compositions; near-infrared spectroscopy; nitrogen protein; starch; sweet potato; taro; total minerals; water scarcity +
Footnote †: journal: Applied Sciences  
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and alcohol [2,5]. The leaves are a good source of protein and minerals, and the tubers are mainly composed of carbohydrates consisting of starch and sugars [5]. The raw consumption of both taro and sweet potato crops is avoided as they contain different oxalic acid concentration as crystals of calcium oxalate (CaOx) in their tissues, especially under stress conditions (e.g., drought), which negatively affects their nutritional value and quality [6, 7, 8]. Protein (Pt), nitrogen (N), starch (St), total minerals (M), crude fiber (Fb), and CaOx are the major quality constituents analyzed by laboratories for both crops, either grown under non-stress conditions [7, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18], or low-input [19], different irrigation [20], rain-fed [21, 22, 23], or other environmental conditions [4, 5, 24, 25, 26]. Taro growth [27, 28] and sweet potato quality under drought conditions have recently been studied [29]. However, the analytical process for the major crop quality constituents is still constrained by cumbersome laboratory protocols. Near-infrared spectroscopy (NIRS) is a fast and reliable spectral technique that allows the screening of numerous varieties, recommended for plant breeding and improvement programs [18, 30, 31]. Due to its speed of analysis, the accuracy of results, versatility, ease of sample preparation, multiple sample determination in a single operation, without using any chemical reagents allied to a low-cost technique, NIRS has been widely used to characterize several parameters in biological samples [30, 31]. The introduction of several new features over the conventional NIR spectroscopy in the last decade led to its development, passing from the optical light beam scatters to the recent inputs of hyperspectral sample surface imaging [32]. NIR spectroscopy uses high-precision spectral techniques that evolve complex computations, operating chemometric algorithms for preprocessing and multivariate data analysis [32, 33]. Beyond quality control through the quantification of major chemical constituents, it is essential to link complex phenotypes and chemotypes to plant breeding in changing environments, especially under drought stress [34, 35].