Partial correlation analysis in the study of morphogenesis and herbage accumulation in Panicum maximum cv. ‘Tanzânia’

• Published in: Ciência rural 2017-01, Vol.47 (9)
• Main Authors: Braz, Thiago Gomes dos Santos, Martuscello, Janaina Azevedo, Santos, Manoel Eduardo Rozalino, Pereira, Vinícius Valim
• Format: Article
• Language: English
• Subjects: Accumulation; AGRONOMY; Correlation analysis; Correlation coefficient; Correlation coefficients; Elongated structure; Elongation; Grasses; Incident light; Influence; Interception; Leaves; Life span; Light; Light interception; Morphogenesis; Nitrogen; Panicum maximum; pasture management; Pearson correlation; plant density; Planting; Quantitative genetics; Software; Stems; Variables
• ISSN: 0103-8478; 1678-4596; 0103-8478; 1678-4596
• DOI: 10.1590/0103-8478cr20161058

The objective of this study was to evaluate, through partial correlation analysis, the degree of association between herbage accumulation and morphogenetic traits of ‘Tanzania’ grass (Panicum maximum Jacq.) defoliated with 95% of light interception and fertilized with nitrogen, under different planting densities. The experiment was carried out in a randomized complete design with 12 treatments and two replicates, in a 4 × 3 factorial arrangement consisting of four nitrogen rates (0, 80, 160, and 320kg ha-1 Yr-1) and three planting densities (9, 25, and 49 plants m-2). Harvests were performed at 25cm above the soil, when the plots intercepted 95% of the incident light. The simple correlation coefficients between herbage accumulation and leaf and stem elongation rates and leaf appearance rate were high and positive. Correlation between herbage accumulation and leaf lifespan; however, was high and negative. The study of partial correlation coefficients revealed considerable changes in the correlation structure, whereby the association with stem elongation had a negative value statistically equal to zero, indicating no relationship between these variables. A similar result was observed for the correlations between herbage accumulation and leaf appearance and leaf lifespan. The partial correlation between accumulation and leaf elongation was different from zero and positive indicating a strong association. In Guinea grass cv. ‘Tanzania’ canopies defoliated at 95% light interception, leaf elongation is the morphogenetic variable with the highest strength of association with herbage accumulation. RESUMO: Objetivou-se avaliar, por meio de correlação parcial, o grau de associação entre o acúmulo de forragem e as características morfogênicas do capim-tanzânia (Panicum maximum Jacq.) desfolhado com 95% de interceptação luminosa e adubado com nitrogênio em diferentes densidades de planta. O delineamento foi em blocos completos casualizados, com 12 tratamentos e duas repetições em esquema fatorial 4 × 3, constituído por 4 doses de nitrogênio (0, 80, 160 e 320kg ha-1 ano-1) e três densidades de plantas (9, 25 e 49 plantas m-2). As colheitas foram realizadas a 25cm do nível do solo quando as parcelas interceptavam 95% da luz incidente. Os coeficientes de correlação simples foram altos e positivos, entre o acúmulo de forragem e as taxas de alongamento de folha e de colmo e aparecimento de folha. Já a associação do acúmulo com a duração da vida das folhas foi alta e negati