Impact of Deficit Irrigation (DI) and Root-Zone Drying Irrigation Technique (PRD) under Different Nitrogen Rates on Radiation Use Efficiency for Potato (Solanum Tuberosum L.) in Semi-arid Conditions (II)

The study was carried out at the Technical Center of Potato and Artichoke CTPTA located in the lower valley of Medjerda river of Tunisia during the season of 2017. The purpose was to estimate the impact of deficit irrigation (DI) and the root-zone drying irrigation technique (PRD) under different nitrogen rates on photo synthetically active radiation absorbed and radiation use efficiency for Potato (Solanum Tuberosum L. VS. Spunta). Three water treatments (T1= 100% ETC, T2 = DI = 75% ETC and T3 = PRD50) and three nitrogen rates (F1 = N150: 150 kg N ha-1, F2 = N75: 75kg N ha-1, F3 = N0: 0kg N ha-1) were applied since the tuber initiation (55 days after planting) to maturity (100 days after planting). The deficit irrigation T2 has no effect on PARabs. Besides, the PRD50 has led to a reduction in PARabs. This decrease compare to T1 was equal to (8.9; 9.9 and 7.9%) respectively for the three treatments (F1; F2 and F3). The nitrogen deficit affects negatively the PARabs. An improvement of 13.2%, 11.2% and 12.2% of the F1 compared to the F3, respectively for the three water treatments (T1, T2 and T3). The T2 has no effect on RUE TDM. Conversely, the PRD50 has led to a reduction in RUE TDM. This decline referee against T1 was equal to (12.7; 17.4 and 21.5%) respectively for the three treatments (F1; F2 and F3). For RUEGY statistical analysis showed significant (P < 0.05) difference between the three irrigation treatments (T0, T1 and T2) for the three nitrogen treatments (F1; F2 and F3). The T2 and the PRD50 has led to a reduction in RUE GY. This decrease judge against T1 respectively for the two treatments (F2 and F3) was equal to (14.9 and 21.5%) and (19.6 and 31.2%).