OIL CONTENT AND OIL YIELD OF DILL (ANETHUM GRAVEOLENS L.) HERB UNDER SOME AGRONOMIC PRACTICES

In order to exploit dill herb (Anethum graveolens L.) as an essential oil crop, the influence of agronomic practices like time of sowing, seed rate, row spacing, nitrogen and phosphorus was studied at Punjab Agricultural University during winter seasons of 1982–83 and 1983–84. The herb was harvested at five stages (flowering, seed formation on primary umbels, seed formation on secondary umbels, seed formation on tertiary umbels, milk stage and maturity) to obtain optimum stage of harvesting for higher oil content and oil yield. The experimental field was loamy sand in texture, having normal pH and electrical conductivity. The site was low in organic carbon, available nitrogen, potassium and high in phosphorus. In these separate sets of experiments, the above agronomic practices were evaluated in dates of sowing (30 September, 15 October, 30 October, 15 November, 30 November and 15 December) trial; seed rates and row spacings (5, 10, 15 kg/ha and 30, 45, 60, 75 cm) trial and nitrogen x phosphorus (0, 30, 60, 90, 120 kg N/ha x 0, 20, 40 kg P₂O₅/ha) trial. The results indicated that under all the agronomic factors tried in different experiments, the oil content in dill herb increased with the delay in harvesting from flowering to milk stage beyond which it decreased at maturity. The maximum oil content in fresh herb was recorded at milk stage under 15 October sowing during both the years. The highest oil yield was recorded under 15 October and 30 September sowings at milk stage during 1982–83 and 1983–84 respectively. The oil content in herb increased with the increase in nitrogen and phosphorus up to the highest levels tried in both the years. In case of various seed rates and row spacings, the highest oil content in herb was observed again at milk stage.