Dynamics of correlation of spectral vegetation indices with breeding parameters of Pisum sativum

Abstract

The nature and significance of the correlation between the vegetation indices calculated on the basis of multispectral UAV imagery (NDVI, MSAVI2, clGreen, NDRE, NGRDI, NDYI) and the breeding-significant parameters of peas: yield, morphotype, plant length, lodging resistance, and the periods of development of Pisum sativum L plants most acceptable for multispectral imagery were identified. The studies were conducted in the forest-steppe of the Krasnoyarsk Region, in the nursery of the competitive variety testing of peas at the Federal Research Center “Krasnoyarsk Science Center” of Siberian Branch of Russian Academy of Sciences, in 2022 and 2023. The conditions in 2023 were more arid (HTC (hydrothermal coefficient) = 0.82) compared to 2022 (HTC 2022 = 1.04). The soil of the site was ordinary chernozem with neutral acidity. The research targets were pea plots in the nursery of the competitive trial: in 2022, there were 176 plots (44 accessions in 4-fold repetition); in 2023, there were 128 plots (32 accessions in 4-fold repetition). It was found that the spectral indices should be studied approximately during the flowering period of the crop when the indices and correlations with the main breeding parameters were at maximum - in June and July. During that period, the maximum degree of correlation between the main spectral coefficients was reached. The dependence on yield was defined as an average positive, with boundary values from 0.324 (NDYI) to 0.396 NDRE. The recommended shooting dates were June and July. A predominantly strong positive relationship was determined with the plant morphotype, with the most significant average index value of r = 0.745 (ClGreen). The average negative correlation was determined with the lodging resistance, with the most significant average coefficient of r = - 0.567 - the MSAVI2 index, the recommended dates for the prediction of lodging resistance - July. The correlation with plant length did not exceed the average positive dependence, and its maximum value was determined with the NDYI index (r = 0.596). The recommended shooting period was July.