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Abstract

Understanding 4R (the right method, time, source, and dose) phosphorus (P) management of sunflower can help promote its economic production. A thrice replicated field study was conducted in sunflower (cv. Hysun-39) following split-split plot design with two P methods and timings (main), i.e. banding near seed rows at sowing and broadcasting at land preparation), two P sources (sub), i.e. monoammonium phosphate (MAP) and diammonium phosphate (DAP), and five P doses (sub-sub), i.e. 0, 30, 60, 90 and 120 kg P2O5 ha-1. The results revealed that banding, as against P broadcasting, was better method to apply P to sunflower, which offered maximum achene per disc, 1000 achene weight, achene and stalk yield, and P concentration of achene, stalk, and leaf. The MAP was better P source than DAP in enhancing plant height, disc dia, 1000 achene weight, and stalk and leaf P concentration, however, statistically similar to that of DAP in producing achene per disc, and achene and stalk yield. Increasing P doses increased yield traits (except plant height) and yield of sunflower, in addition to increasing P concentration of achene, stalk, and leaf, with highest values noted at 120 kg P2O5 ha-1. The significant 2-way interactive effect between two P application methods × five P doses was noted for banding × 120 kg P2O5 ha-1, which produced maximum achene per disc, 1000 achene weight, achene and stalk yield, and stalk and leaf P concentration. The significant 2-way interactive effect between two P sources × five P doses was found for MAP × 90 kg P2O5 ha-1 (statistically equal to that of 120 kg P2O5 ha-1 × MAP or DAP) which produced maximum stalk yield, and stalk and leaf P concentration. The significant 3-way interaction between two P application methods × two P sources × five P doses was noted for banding × 120 kg P2O5 ha-1 × MAP or DAP, which produced maximum stalk P concentration. Phosphorus uptake of sunflower achene was highest in case of banding, as against broadcasting, which increased linearly with the increasing dose of P to reach at its maximum at 120 kg P2O5 ha-1. The significant 2-way interactive effect was noted for banding × 120 kg P2O5 ha-1, which resulted in maximum P uptake by sunflower achene. It was followed by the P uptake noted for banding × kg 90 P2O5 ha-1, which was interestingly statistically at par with the broadcasting × 120 kg P2O5 ha-1. Phosphorus efficiency (kg increased yield per kg applied P) decreased with the increasing dose of P application and was found to be maximum at 30 kg P2O5 ha-1. The 4R P technology developed for sunflower in this research study suggests that P should be applied to sunflower through banding near seed rows at the time of sowing preferably through monoammonium phosphate (MAP) either at 30 kg P2O5 ha-1 (for economic production) or at 90 kg P2O5 ha-1 (for maximum production). We recommend further studies on the subject involving other crops.

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