Use of the minirhizotron-miniature video camera technique for measuring root dynamics

Abstract

Root measurement techniques for annual row crops that are non-destructive, quick and efficient, and quantitative measures of root dynamics are critical to understanding environmental effects on rooting. This paper describes, utilizing data from Minirhizotron (MR) and miniature color video camera recordings, wheat ( Triticum aestivum L.) and peanut ( Arachis hypogae L.) seasonal rooting habits. Data for multiple and linear regression analysis were acquired by making root count ( C a, counts cm −2 MR) and root length ( L a cm root cm −2 MR) measurements on the surface of MR during the plant growing season. Roots on the surface of MR were recorded on video cassettes, displayed on a video screen, and traced on cellulose acetate each sampling date. Root dynamics were determined by comparing successive tracings. Wheat root length density ( L v cm root cm −3 soil) and root dry weight ( W v g root cm −3 soil) were determined from soil cores. A correlation coefficient of 0.88 for a multiple regression expression describing C a as a function of cultivar, sampling date, and soil depth was obtained. Linear regression for C a as function of L v W v or L a were highly significant, and correlation coefficients with C a were 0.72, 0.69, and 0.82, respectively.