A amostragem da cana-de-açúcar para determinações tecnológicas

A amostragem da cana-de-açúcar para determinações tecnológicas^*

F. Pimentel Gomes; O. Valsechi; Clovis P. de Abreu; Enio Roque de Oliveira

Escola Superior de Agricultura «Luiz de Queiroz»

SUMMARY

The authors carried out 3 experiments on the sampling of sugar cane for technological determinations, one with each of the varieties Co 419, CB 40-69 and CB 41-58, in Piracicaba, State of São Paulo, Brasil. The main intent of the project was to compare 2 methods of sampling, namely:

1) Method A, where the sample is a hill (CATANI et al, 1959) or, more generally, 20 stalks all together in a randomly selected point of the furrow;

2) Method B, where 20 stalks are taken, from 20 points evenly spread but on the whole plot.

Coefficients of variation for 20 stalk samples

Variety Characteristic 20 stalks per hill 1 stalk per hill

Brix 4.8% 1.9%

Pol 6.4% 2.5%

CB 40-69 Coefficient of purity 2.1% 0.83%

Available sucrose 7.3% 2.7%

Weight 6.6% 6.9%

Brix 5.3% 1.8%

Pol 7.6% 2.6%

Co 419 Coefficient of purity 2.9% 1.0%

Available sucrose 8.6% 3.0%

Weight 21.2% 6.5%

Brix 2.8% 1.4%

Pol 4.1% 1.9%

CB 41-58 Coefficient of purity 1.8% 0.8%

Available sucrose 5.0% 2.2%

Weight 10.9% 6.2%

For the 3 varieties studied and for the data on Brix, pol, coefficient of purity, available sucrose and weight, analyses of variance were carried out. Further computations led to the following coefficients of variation.

For available sucrose, which is probably the most important characteristic studied, the average coefficient of variation for the 3 varieties was 2.7%, for the case of method B, that is, 20 stalk samples, one stalk per hill. Assuming this coefficient of variation, in a trial with 5 treatments and 6 replications, in randomised blocks, the least significant difference among treatment means, at the 5% level, would be 4.7% of available sucrose by Tukey's test, and 3.3% by the t test. For the case of method A the average coefficient of variation is 7.0% and, in similar conditions, the least significant difference would be 15.1% by Tukey's test, and 12.1%

by the t test. Since differences of available sucrose among treatments in experiments with fertilizers seldom are higher than 3 or 4% of the mean (PIMENTEL GOMES & CARDOSO, 1958), method B with a 20 stalk sample per plot gives more or less the minimum amount of cane to be sampled for technological determinations. In experiments with varieties, however, where differences may be assumed to be higher, a sample of 10 to 20 stalks one per hill, can be enough.

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AGRADECIMENTO

Os autores agradecem à Refinadora Paulista S/A., que nos cedeu o material para o presente ensaio. Estes agradecimentos são extensivos ao Dr. Crucciano Crucciani, chefe da Secção Agrícola, da Usina Monte Alegre, em Piracicaba, e ao Sr. Antonio Brunharo. chefe do Setor Agrícola de Taquaral, da mesma usina.

BIBLIOGRAFIA

ALMEIDA, J. R., O. VALSEHI, F. PIMENTEL GOMES, E. M. CARDOSO e N. CAMOLESI, 1952 - El Florescimento en la Variedad de Cana Co 421, Memoria de la Conf. An., As. Tecnol. Azuc. de Cuba, 100 pp., Havana.

ASSOCIATION OF OFFICIAL AND AGRICULTURAL CHEMISTS, 1960 - Official Methods of Analysis, 9.a ed., A. O. A. C, 418 pp., Washington.

BROWNE, C. A. e F. W. ZERBAN, 1941 - Physical and Chemical Methods of Sugar Analysis, 3.a ed., John Wiley & Sons, Nova York.

CATANI, R. A., H. C. ARRUDA, D. PELLEGRINO e H. BERGAMIN FILHO - 1959 - A absorção de Nitrogênio, Fósforo, Potássio, Cálcio, Magnésio, Enxofre e Silício pela Cana-de-Açúcar, Co 419, e o seu Crescimento, em Função da Idade. Anais E. S. A. «Luiz de Queiroz» 16: 167-190.

COCHRAN, W. G. e G. M. COX - 1957 - Experimental Designs, 2.a ed., 611 pp. Nova York.

COURY, T., E. MALAVOLTA, F. PIMENTEL GOMES, J. D. P. ARZOLLA, M. O. C. BRASIL SOBRINHO, H. P. HAAG, F. A. F.

MELO, R. F. NOVAES, G. RANZANI e L. MENARD - 1957 - A Diagnose Foliar na Cana-de-Acúcar, 28 pp., São Paulo.

PIMENTEL GOMES, F. e ENO M.CARDOSO - 1958 - A Adubação da Cana-de-Açúcar, 116 pp., Piracicaba.

PIMENTEL GOMES, F. - 1963 - Curso de Estatística Experimental, 2.a ed., 384 pp., + 15 tabelas. Piracicaba.

SPENCER, G. L. e G. P. MEADE - 1932 - Manual de Fabricantes de Azucar de Caña e Químicos Azucareros (trad.) 7.a ed., John Wiley & Sons., 412 pp., Nova York.

VEIGA, F. MENEZES - 1959 - Estação Experimental de Campos - Relatório do Instituto do Açúcar e do Álcool, 95 pp., Rio de Janeiro.

*

Trabalho realizado com o auxílio da Fundação de Amparo à Pesquisa do Estado de São Paulo e da Fundação Rockefeller.

Datas de Publicação

• Publicação nesta coleção
  06 Set 2012
• Data do Fascículo
  1963