Vegetative growth and nutrient absorption in cauliflower

摘要

Vegetative growth and nutrient absorption of cauliflower (Brassicae oleracea L. botrytis) cv. Profil was studied and quantified at a density of 5 plants m~(-2). Fertilisers were incorporated in the irrigation water following the percentage of nutrient uptake for broccoli. Plants were sampled, fractionated (leaves, stems and curds), dried and weighed and the macronutrient content was analysed every 15-20 days. Sampling was carried out over a period of 96 days after transplanting and during this time31.3 t ha~(-1) of curds were picked. The total amount of dry matter produced was 6,96 t ha~(-1). Curds constituted 55.4 percent, leaves 35.8 percent and stems 8.8 percent of the total dry matter. The leaf area index was 6.5 at 96 days after transplanting, and the highest leaf efficiency, expressed as net assimilation rate (NAR), was obtained between days 0 and 26 after transplanting. The maximum growth rate of (CGR) occurred between days 68 and 82 after transplanting. Leaf growth rate (LGR) increased until the swelling of the first head. The highest curd growth rate (FGR) occurred between days 68 and 96 after transplanting. The total amount of nitrogen extracted by the crop during the sampling period was 313 kg ha~(-1), 29.5 percent of which was contributed by the head. The total amount of phosphorus extracted by the crop was 39.2 kg ha~(-1), 32.5 percent of which accumulated in the curds. The quantity of potassium accumulated by the crop was 305.3 kg ha~(-1), 31.3 percent of which was accumulated bythe curd. The total amount of Ca absorbed by the crop was 118.6 kg ha~(-1), 89.2 percent of which was accumulated by the leaves. The total quantity of Mg absorbed by the crop was 35.1 kg ha~(-1), 80.3 percent of which was accumulated by the leaves. In summary, the highest concentration of N, Ca, and Mg were accumulated in the leaf, K in the stem, and P in the curd. The highest uptake rates of N, P, K, Ca and Mg took place in the period of highest curd growth. The highest specific accumulation of N, P,K, Ca and Mg occurred during the initial stages of growth, when the leaf efficiency is highest.