Acessibilidade / Reportar erro

Differential accumulation of nutrients by five cultivars of corn (Zea mays L.): I - macronutrients accumulation

The objective of the present work was to examine the differences in growth, yield, accumulation and transport of nutrients between the cultivars Agroceres 256, Agroceres 504, Centralmex, H-7974 and Piranão. The experiment was carried out in the municipality of Piracicaba, State of São Paulo, Brazil. The soil type was a sandy oxisol of medium fertility, expect for K which was low. The experimental set-up was a randon block design with four replications. Common cultivation practices were followed, and the fertilizer used consisted of 83 g of a formula: 30-120-70, per meter length at planting, and 33 g of the formula: 50-0-45 per meter length as dressing 22 days after germination. The plant population density was 50,000 per hectare. Plants were collected for analysis at 20 days after germination, and there after at intervals of 20 days up to 120 days. The plants were divided into "stems + leaves", tassels, and ears for chemical analysis of N, P, K, Ca, Mg and S. Conclusions: Growth - The cultivars produce maximum quantities of dry matter of 327 to 381 g per plant at the age of 100 to 106 days. - Differences between cultivars in terms of dry matter accumulation in the vegetative parts of the plant is not necessarily relate to the dry weight of the ear. Accumulation of nutrients - There are no differences in the quantity of N, P and K taken-up by the cultivars, although during the period of rapid growth some differences may appear. - Differences in the accumulation of Ca, Mg and S are detected when the quantities of these nutrients approach the maximum. The cultivar H-7974 presented the highest quantities of Ca and Mg where as Agroceres 504 was richest in S. - The maximum level of nutrients are attained in the following period in days: N (89-100); P (101 -120); K (58-66); Ca (75-94); Mg (100-120) and S (93-95). - The maximum quantities taken-up in mg/plant are:N (3,169-3,878);P (541-642); K (3,850-4,693); Ca (582-782); Mg (654-943); S (444-799). Yield - No differences were found between cultivars for grain production. Transport of nutrients - The re were no differences in the amounts of nutrients in the grain between cultivars. - The transport of nutrients into the ears of the different cultivars are the following order (per hectare harvested, 50,000 plants): N (111-143 kg); P (22-30 kg); K (30-45 kg); Ca (0.7-1.1 kg); Mg (10-12 kg) and S (9-13 kg).


Universidade de São Paulo, Escola Superior de Agricultura Av.Páduas Dias, 11, C.P 9 / Piracicaba - São Paulo, Brasil, tel. (019)3429-4486, (019)3429-4401 - Piracicaba - SP - Brazil
E-mail: scientia@esalq.usp.br