Rhizome differentiation in yellow nutsedge (Cyperus esculentus L.), cultured under 12½, 14, and 15½-hr photoperiods, 21–16, 27–21, and 33–27 C temperatures (day and night, respectively), Hoagland solutions of 1/32, 1/8, and 1/2 strength nitrogen (N), and 0, 10, and 1000 ppm gibberellin (GA), was investigated in controlled-environment chambers.
High levels of N, long photoperiods, and high levels of GA at the shortest photoperiods inhibited tuberization whereas high temperatures at the lowest N level favored tuberization. Shoot formation was promoted by high levels of N, long photoperiods, and high temperatures under 12½ and 14-hr photoperiods while GA had a retarding effect. The higher levels of N, temperature, and GA decreased carbohydrate level whereas the longer photoperiods increased it.
It may be concluded that tuberization is not only the result of surplus carbohydrates in the plant but is controlled also by some GA-like substances regulated in the plant under specific conditions of photoperiod and temperature.