Jimba Rabgyal, Rupmeena Biswa, Pempa Lhamo Lepcha, Tshering Yangdon & Yadunath Bajgai
The effect of different irrigation intervals and manure rates on agronomic parameters of dill were evaluated under three agro-ecological zones of Bhutan: ARDC-Bajo located at 1200 m asl, ARDC–Wengkhar at 1,700 m asl, and NCOA–Yusipang at 2700 m asl. The split-plot design arranged in randomized complete blocks with three replications was employed. The four levels of irrigation interval (control, every 3 days, every 7 days, and every 14 days) were allotted to main plots and four levels of manure (Control, 4 tons/acre, 8 tons/acre and 12 tons/acre) were allocated to subplots. The results showed that dill can be successfully grown in all agro-ecological zones under study. Fresh yield obtained at ARDC-Wengkhar (1.92 tons/acre) was significantly higher compared to that at NCOA-Yusipang (0.52 tons/acre) but not significant to that at ARDC-Bajo (1.41 tons/acre). Interaction of irrigation interval and manure rate significantly influenced plant height (P=0.02) and stem diameter (P=0.03) at NCOA–Yusipang, and stem per plant (P=0.02) at ARDC-Wengkhar. The irrigation interval of 3 days produced significantly better results except for the fresh to dry weight ratio at NCOA-Yusipang. Irrigation interval of 7 days yielded better results at ARDC-Bajo and ARDC-Wengkhar except for FDR at ARDC-Wengkhar. The increase in irrigation interval beyond 7 days resulted in 62% and 25% lower fresh yields at ARDC-Bajo and NCOA-Yusipang respectively. In contrast, irrigation at 3 days interval at ARDC–Wengkhar decreased the yield by 55% compared to 7 days interval. The manure treatments did not influence any of the parameters assessed at all sites. However, MR 8 tons/acre at NCOA–Yusipang, MR Control at ARDC-Wengkhar and MR 12 tons/acre at ARDC-Bajo yielded higher fresh yields compared to other manure treatments. We recommend the combined application of IR 7 days x MR 12 tons/acre, IR 7 days x MR 4 tons/acre, and IR 3 days x 8 tons/acre at ARDC–Bajo, ARDC-Wengkhar and NCOA–Yusipang respectively. Further, this research provides a reference guide for agricultural extensionists during promotional, advocacy and capacity development programs.
Keywords: Anethum graveolens; Irrigation Interval; Manure Rate; Split-plot Design