Rooting depth and rooting density of corn and sorghum under rainfed condition
1985
Thanom Klodpeng | Charoon Sukasame | Chaiyawoot Nimmalungkul (Chiang Mai Univ., Chiang Mai (Thailand). Faculty of Agriculture)
Field corn (Suwan no.1) and sorghum (KU 439) were seeded on typic Paleaquults, fine loamy soil under rainfed condition at the experimental farm, Faculty of Agriculture, Chiang Mai University on August 1, 1984 with plant spacings of 25x75 cm. and 10x75 cm. for corn and sorghum, respectively. Root depth, number of roots, and root density were measured by frame monolith method at 15 DAE (days after emergence) and every 15 days interval through out the growing period. Undisturbed soil samples were taken to determine soil bulk density and moisture content at the same time of root sampling. The results showed that, at the early stage of growth, corn roots penetrated at a higher rate than sorghum. However at the 45 DAE, root penetrations exceeded 100 cm. depth for both crops. Number of roots and root density for corn and sorghum were maximum at the 45 DAE on the top soil and decreased rapidly with soil depth. This was probably associated with the increase in soil bulk density. The decrease in corn roots with soil depth, however, was more pronounced than that observed in sorghum. As a results, the number of sorghum roots tended to be higher at lower depths even though the total roots of corn for the whole soil profile was higher. The correlations between number of roots and root density with soil depth were exponential sigmoid growth, regardless of growth stages for corn. For sorghum, however, this relationship was observed only at the earlier stages. At a later period, a better correlation was obtained with a sigmoid growth type.
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