The number of branches per plant is an important morphological character, directly related to yield in soybean. In the present investigation, number of branches per plant increased gradually up to 75 days (Table 7.1). Further, the different growth regulator treatments studied differed significantly at 45, 60, 75 DAE and harvest and maximum number of branches per plant were recorded in NAA (20 ppm), followed by chlormequat chloride 50 % SL (162.5 a.i/ha). Similar results were reported by Deotale et al. [6] in soybean. Application of mepiquat chloride 5 % AS (5 %) and brassinosteroid (25 ppm) had also recorded significantly higher number of branches per plant, compared to control in the present study. Similar results were reported earlier in black gram [8] and green gram [7].

In general, leaf is considered as an important functional unit of plant which contributes to the formation of yield. The number of trifoliate leaves increased gradually from 15D AS to 60 DAE, and thereafter declined (Table 7.1) due to senescence. Significant influence of the growth regulator treatments was noticed at 30, 45, 60, 75 DAE and harvest. All treatments, with the exception of chlormequat chloride 50 % SL (375 a.i/ha) at 60 and 75 DAE, increased the number of trifoliates significantly, compared to control. The positive influence of chlormequat chloride and NAA [8]; and mepiquat chloride and brassinosteroid [9] on number of trifoliates per plant were also reported earlier. Among the growth regulators, NAA (20 ppm) was more effective followed by brassinosteroid (25 ppm).

Poor partitioning of photo assimilates to the growing reproductive parts is one of the major constraints in pulses. This can be overcome by applying synthetic plant growth regulators. The dry matter production in leaves increased up to 60 DAE and declined (Table 7.2) thereafter till harvest in all the growth regulator treatments including control. Among the treatments, the leaf dry weight was significantly higher with the application of NAA (20 ppm), brassinosteroid (25 ppm), mepiquat chloride 5 % AS (5 %) and chlormequat chloride 50 % SL (137.5 and 162.5 a.i/ha), compared to control and water spray, due to the beneficial effect of these growth regulators on leaf development. Similar results with foliar application of 50 ppm NAA at flowering in soybean and pigeon pea were obtained by Merlo et al. [10]. The data recorded (Table 7.2) on dry matter production in stem revealed gradual increase up to 75 DAE. Among different growth regulator treatments NAA (20 ppm) exhibited maximum stem dry matter followed by brassinosteroid (25 ppm), chlormequat chloride 50 % SL (137.5 a.i/ha) over control and other treatments studied. Similar results in increase in stem dry matter was observed by Chandrasekar and Bangarusamy [11] in green gram with the application of NAA @ 40 ppm. Dry matter production, particularly in reproductive parts is an important yield contributing character. There was a gradual increase in dry matter production of pods (Table 7.2) from 60 DAE to harvest stage, and the highest dry matter was observed at harvest stage. Further, among the growth regulators treatments, NAA (20 ppm) followed by brassinosteroid (25 ppm) and chlormequat chloride 50 % SL (162.5 a.i/ha) had recorded maximum dry matter in pods, compared to control and other treatments studied. Similar increase in dry matter of reproductive parts with the application of NAA @ 20 ppm in soybean [4]; and chlormequat chloride in soybean [12] were reported earlier.