The Effects of Phosphorus Nutrition on the Growth and Seed Yield of Soybean (Glycine max (L.) Merril.)
Togun, A.O1 and *Sakpere, A.M.A2
1Department of Crop Protection and Environmental Biology, University of Ibadan, Ibadan, Nigeria. 2Department of Botany, Obafemi Awolowo University, Ile-Ife, Nigeria.
Accepted in January 2004
An analysis of the effect of phosphorus nutrition (0, 25, 50, 100 and 200 kg p/ha SSP) on the performance of two varieties of soybean (TGx 536-02D and TGx 1485-1D) was carried out in pot experiment at the University of Ibadan. The experiment was a split-plot arrangement, with cultivars as main plots and phosphorus (P) nutrition levels as sub-plots. The experiment was laid out in a Randomized Complete Block design with five replicates. Growth and development attributes were determined by periodic plant sampling and yield attributes assessed by sampling at maturity (final harvest [FH]). Data collected were subjected to analysis of variance and means compared with the least significant difference (LSD) at P = 0.05. The responses of the two cultivars to P were similar although TGx 536 – 02D (V1) generally performed significantly better than TGx 1485 – 1D (V2). Growth and yield attributes were enhanced with increase in P levels up till 50kg P/ha and then there was a gradual decline. Application of 50kg P/ha was not significantly (P = 0.05) different from 25kg P/ha in most of the growth and yield attributes although they were both significantly different from the control. The reproductive efficiency of the plants was also at optimum level with the application of 50kg P/ha though not significantly different from 25kg P/ha. It would appear that under the prevailing local condition, application of between 25kg P/ha – 50kg P/ha (a total of 39.14kg – 64.14 kg soil P/ha) is adequate for soybean production. Excessive application could degrade the soil and reduce yield with negative environmental effects.