Características da planta, teores de nitrogênio na folha e produtividade de tubérculos de cultivares de batata em função de doses de nitrogênio / Plant characteristics, leaf nitrogen contents and tuber yield of potato cultivars in function of nitrogen rates

AUTOR(ES)
DATA DE PUBLICAÇÃO

2007

RESUMO

This study was carried out to evaluate the effects of nitrogen (N) rates on tuber yield and on the following variables measured on the fourth leaf of potato (Solanum tuberosum) cultivars: green intensity (determined by SPAD index and color chart), physiological index (area, length, width, leaflet number, fresh and dry weight) and N index (petiole sap NO3 and N contents in the dry matter). Four experiments were simultaneously conducted in a in Red Yellow Argisol Cambic soil during the autumn/winter season at Universidade Federal de Viçosa. In each experiment one potato cultivar were planted and were evaluated five N rates: 0, 50, 100, 200 and 300 kg ha-1 as ammonium sulfate pre-planting applied. Each experiment was set up in a randomized block design with four replicates. At 21 days after plant emergence, SPAD indexes measured in the fourth leaf of Atlantic, Ágata, Monalisa and Asterix reached 46,48; 43,02; 44,64 and 49,95 with N rate that provided the maximum commercial tuber yield. The correspondent values for the green intensity notes were 5,01; 4,34; 4,10 and 5,00, respectively. Among the physiological indexes, only the fourth leaf area (AQF) presented significative and positive correlation with commercial tuber yield for all cultivars. With the N rate that provided the maximum commercial tuber yield of Atlantic, Ágata, Monalisa and Asterix the following values were obtained for AQF: 191; 185; 150 and 151 cm2; for NO3 in the petiole sap: 2264, 2033, 2182 and 2351mg L-1, and for N-NO3 - and Norg contents in the leaf dry matter: 0,44; 0,32; 0,42 and 0,54 dag kg-1 and 7,80; 7,44; 7,90 and 5,97 dag kg-1, respectively. Increasing in N rates increased commercial tuber yield, following a quadratic function. Atlantic, Ágata, Monalisa and Asterix maximum yield was 33,30; 33,06; 25,93 and 32,30 t ha-1 achieved with 175,5; 168,2; 193,2 and 212,2 kg ha-1 of N, respectively.

ASSUNTO(S)

nutrição diagnosis diagnóstico nutrition batata solanum tuberosum fitotecnia potato solanum tuberosum

ACESSO AO ARTIGO

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