Three Dimensional Spatial Characterization of Coffee Plant Root System.

During growth and development of roots into the soil matrix, plant genetic characteristics and soil environment govern the way roots penetrate and exploit the soil around them. Genetic characteristics will determine root branching and growth patterns.  Soil environment will affect not only the way roots grow, but also other related processes such as water absorption, nutrient transport and biological activities in the vicinity of root system. The proper comprehension of how roots are distributed in the soil might help to avoid misleads in agricultural practices. Knowing the economical importance of coffee plants as a source of income in several countries, the aim of this research was to characterize the spatial distribution of coffee plants root system in order to maximize agricultural practices. Three undisturbed soil cores (2x10⁵.cm^-3) were collected and cultivated with 18 months old coffee plants during 18 months. The coffee plants utilized are inter-specific hybrids between Coffea arabica and C.racemosa, named as Siriema cultivar. The soil was classified as Red-Yellow Latosol. Forty four soil samples were taken in a grid pattern at depths of 10, 30, 50 and 70 cm. These soil samples were washed and sieved in order to separate the roots, which were analyzed by using the STD 1600 WhinRhizo analysis system. With the obtained data it was calculated the total RLD (root length density, cm.cm^-3) for each root sample. Also, it was calculated the RLD for roots with different diameters. Based on these results, RLD maps were prepared for each soil depth. These maps represented the average of the three undisturbed soil cores. Finally, knowing the RLD´s, the root samples position and their soil depth, three dimensional maps were prepared. The obtained RLD maps showed that there was spatial variability for all root diameters along the soil profile and also for each soil depth analyzed.