To understand the contribution of mother shoot and tillers for root growth, the effect of defoliation of mother shoot/tillers on the seminal and nodal roots of four wheat varieties, namely, C 306, HD 1553, HD 1593 and NP 846, was analysed. Roots were removed by washing technique and observations on number, length and weight of seminal and nodal roots were recorded at various intervals, In an another experiment, the translocation of photosynthates to seminal and nodal root was studied by 14CO2 feeding of basal leaves of the mother shoot and the first tiller and in the wheat variety HD 1593. The defoliation experiment revealed that the contribution of the mother shoot to root growth was significantly higher than the tillers contribution. This was further confirmed by 14C feeding study, which indicated that when mother shoot leaf was fed translocation of 14C to root zone was higher than that of tiller leaf feeding. It was, thus, seen that root growth was mainly dependent on the photosynthates from mother shoot and contribution of photosynthates from tillers was very little. It was also contended from both the experiments that the dependence of nodal root growth was more on photosynthates while seminal root growth was related with the size of seeds substantively.
