Nutrient Uptake and Yields of Four Sweet Potato Cultivars Grown in Soilless Culture at Three N, P and K Different Levels

摘要

An experiment was performed to determine the uptake of macronutrients and yields in plants from four sweet potato cultivars ('Huambachero', 'Toquesita', 'Jewel' and 'Camote Sal') grown during summer-fall at the Hydroponics Module of the Universidad Nacional Agraria La Molina, Lima, Peru. Plants were grown in quarry sand and watered with nutrient solutions containing three different N, P and K concentrations (mg L"1): 1) 125-20-200, 2) 175-40-250 and 3) 225-60-300. Tuber root development began at 35 days after transplanting and the total crop cycle was 130 days. The highest plant dry weight, tuber root dry weight and yield (tuber root fresh weight) were obtained with the 125-20-200 mg L"1 treatment. The nutrient solution containing the highest N, P and K concentration (225-60-300 mg L"1) produced the lowest growth and yield in the four evaluated cultivars. Being a forage cultivar, 'Camote Sal' did not produce tuber roots. There were significant differences in the dry tuber root weight and the totaldry weight between the commercial root ('Huambachano' and 'Jewel') and the forage ('Camote Sal') cultivars, among the commercial tuber root cultivars and, between the forage and the double purpose ('Toquesita') cultivars. There were significant differences found among cultivars in the P, and K uptake in leaves and in the N, P, K, Ca and Mg uptake in tuber roots. N uptake was similar in leaves and tuber roots, but there was a higher P and K uptake in tuber roots than in leaves. There was a higher Ca andMg uptake in leaves than in tuber roots. The highest P uptake in leaves and tuber roots was obtained in the 'Jewel' and 'Toquesita' cultivars respectively. The highest K uptake in tuber roots was observed in 'Huambachero'. Higher N, P, and K levels decreased the total dry weight, the dry tuber root weight and the tuber root fresh weight.