96 THE PEANUT— THE UNPREDICTABLE LEGUME 



Table 3. — Root Development (Penetration in Soil and Spread) in Centimeters 



It would be difficult to arrive at the relative weights of roots and 

 plant shoots since, because of their fragile nature, many roots are lost 

 when removed from the soil. Mohammad et al. (58), reported the green 

 weight of roots of plants 18 days old to be 75.4, 84.5 and 49.5 percent of 

 the green-shoot weight for Small Japan, Small Spanish and Burmese 

 varieties, respectively. At 140 days these values were 3.8, 2.6 and 3.3 

 percent, respectively. The proportion of roots to shoots gradually de- 

 creased with increasing age. Complete recovery of all roots to depths of 

 5 and 6 feet, as these workers attempted, would be difficult, which prob- 

 ably accounts for the low values obtained for older plants. Bledsoe and 

 Harris (10) found that when peanuts were grown in sand culture for 

 130 days, the average green weight of the roots of plants was 13.4 percent 

 of the green weight of the tops. The collective information indicates that 

 the root system of the peanut is much more extensive than is generally 

 realized. 



Adventitious roots sometimes develop on lateral branches of runner- 

 type peanuts when in contact with the soil during humid conditions (37, 

 58) . This has been given little attention but it is probable that such roots 

 occur only on the more recumbent types under favorable moisture and 

 weather conditions. However, at times, these roots might be effective in 

 absorbing nutrients, and, if so, would increase the area of the absorptive 

 system of the peanut. 



Root Hairs 



The majority of papers reviewed state that few if any root hairs occur 

 on the root of the peanut plant. Pettit (63) failed to find root hairs while 

 Waldron (88) found hairs in limited numbers as rosettes at the base of 

 lateral branches and at tips of vigorously growing roots of young plants. 

 Plants in larger containers with less air drainage did not produce tip 

 hairs. Reed (68) observed few rosettes of hairs and no root-tip hairs on 

 field-grown plants. Mohammad et al. (58), found root hairs on peanuts 



