Sowing Time and Plant Density Influence on some Productivity Parameters in Soybean (Glycine max (L.) Merr.)

Abstract

The variation of some productivity parameters in soybean, 'IRIS TD' variety (ARDS Turda), was evaluated in relation to three sowing times (E I, E II, E III), and five row spacing - plane density variants (V1 - V5). The soybean crop was located within the ARDS Lovrin, in a non-irrigated system, on a field with chernozem soil. The experimental variants were placed randomly, in three repetitions. Six productivity parameters were determined at the plant and pod level: pod number per plant (PPN), pod length (PL), pod width (PW), pod shell weight (PSW), grain weight (GW), and soybean pod weight (SPW). The average values ​​were analyzed, across the experimental variants. The results indicated a dominant effect of sowing date, with all traits increasing from E I (17.04.2025) to E III (12.05.2025). For the SPW parameter, the average increased from 4,343 g in the case of E I, to 5,900 g in the case of E II and 6,684 g in the case of E III. The effect of row spacing - plant density was much smaller than the effect of sowing time, and the highest SPW values ​​were observed in E III × V2 (7,183 g) and E III × V3 (6,827 g). Pearson correlations revealed very strong relationships between SPW and PSW (r = 0.976), GW (r = 0.970), PW (r = 0.948), PPN (r = 0.948) and PL (r = 0.935). Principal component analysis showed that PC1 explained 95.18% of the total variance, clearly separating the sowing times on a productivity growth gradient.