Study of the Root System of Local and Improved Sorghum Cultivars Grown in Mali

Roots play a fundamental role in plant growth by supplying water and mineral to the stem and leaves. These underground organs are much less known than the aerial organs mainly due to the difficult access to the root systems in soil. In spite of this, only a few studies were conducted on roots. Given the importance of roots for plant growth, a better understanding of their functioning may help solve some issues such as water stress that can affect the performance of the crops. A total of 100 sorghum cultivars collected in the Sahelian zone of Mali an area receiving an annual rainfall of 200 to 600 mm, were used in a root characterization study. The plant materials were composed of 4 races and 5 intermediates sorghum races. Seeds of the entries were planted directly in PVC tubes of 1m containing soil and arranged in completely randomized design with three replications; in one planting date. Each tube was planted in a dugout ground to 50 cm deep. The tubes were distant of 0.50 m within each row and 0.75 m between rows. The trial was watered from the tap every two days until harvest. The results showed high variability among the varieties studied for root length and root density, with a root length reaching over 1.00m. The study did not identify any pattern in the root systems of the four races and their five intermediates races. However, there was a positive correlation between root length and density indicating an increase in root length correspond to an increased root density. The diversity found in the root system could be a basis for improving root architecture in breeding populations and the evaluation of the behaviour of the sorghum varieties with different root systems in water stress conditions.