Distribuição e crescimento radicular em soqueiras de cana-de-açúcar: dois cultivares em solos com características distintas / Root growth and distribution in sugarcane ratoon: two genotypes in soils with distinctive characteristics

AUTOR(ES)

Mirian Cristina Gomes Costa

DATA DE PUBLICAÇÃO

2005

RESUMO

To test the hypothesis that, in soils with low clay content, sugarcane genotype RB83 5486 has better root system development than genotype RB83 5089, two field experiments were conducted in Porto Feliz, SP. Soils were classified as Typic Kandiudalf and Typic Hapludox. Twelve sugarcane genotypes were cropped in the experimental sites, with a experimental design in randomized blocks. Between the third and fifth ratoon (2002 to 2004), the development of two sugarcane genotypes (RB83 5486 e RB83 5089) was evaluated by determining the chemical and physical soil attributes, crop nutritional conditions, root distribution in the soil profile, and root architecture and vitality in the ratoon sprout. Root distribution in the soil profile was evaluated by the trench method. Root images were taken from trench walls and analyzed using the SIARCS software. This allowed obtaining the root length values at different distances from sugarcane rows and at different soil depths. Root architecture and vitality was analyzed from washed roots sampled by probe at different times. Architecture was evaluated by means of root images that were later analyzed using the WinRhizo software. The vitality of roots was determined by enzymatic tests. Results show differences in hydrogen ion concentrations in both soils. These differences can be related to differences in the uptake of nutrients between the studied genotypes. Potassium and sulphur contents in sugarcane leaves were higher in genotype RB83 5486. However, it was found higher nutrient contents and exportation by stalks in the genotype RB83 5089 due the higher stalk yield. In the Typic Hapludox, most part of roots were concentrated between 0 and 18 cm from sugarcane rows and in the upper 54 cm. In the Typic Kandiudalf, most part of roots were concentrated between 0 and 23 cm from sugarcane rows and in the upper 46 cm. Root growth from ratoon sprout was influenced by precocity characteristics of genotypes. Stalk yield was higher in genotype RB83 5089, however, sugar yield was higher in genotype RB83 5486. The genotype RB83 5486 demanded less amount of nutrients by Kg of produced sugar in the Typic Hapludox.

ASSUNTO(S)

soca sistema radicular sugarcane caracterização do solo soil classification soil characterization classificação do solo ratoon root system cana-de-açúcar

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