Sugarcane root length density and distribution from root intersection counting on a trench-profile

Abstract

Root length density (RLD) is a critical feature in determining crops potential to uptake water and nutrients, but it is difficult to be measured. No standard method is currently available for assessing RLD in the soil. In this study, an in situ method used for other crops for studying root length density and distribution was tested for sugarcane (Saccharum spp.). This method involved root intersection counting (RIC) on a Rhodic Eutrudox profile using grids with 0.05 × 0.05 m and modeling RLD from RIC. The results were compared to a conventional soil core-sampled method (COR) (volume 0.00043 m 3 ). At four dates of the cropping season in three tillage treatments (plowing soil, minimum tillage and direct planting), with eight soil depths divided in 0.1 m soil layer (between 0-0.6 and 1.6-1.8 m) and three horizontal distances from the row (0-0.23, 0.23-0.46 and 0.46-0.69 m), COR and RIC methods presented similar RLD results. A positive relationship between COR and RIC was found (R 2 = 0.76). The RLD profiles considering the average of the three row distances per depth obtained using COR and RIC (mean of four dates and 12 replications) were close and did not differ at each depth of 0.1 m within a total depth of 0.6 m. Total RLD between 0 and 0.6 m was 7.300 and 7.100 m m -2 for COR and RIC respectively. For time consumption, the RIC method was tenfold less time-consuming than COR and RIC can be carried out in the field with no need to remove soil samples. The RLD distribution in depth and row distance (2-D variability) by RIC can be assessed in relation to the soil properties in the same soil profiles. The RIC method was suitable for studying these 2-D (depth and row distance in the soil profile) relationships between soil, tillage and root distribution in the field. Key words: Brasil, root mapping, root study methods, trench-profile method Densidade de comprimento e distribuição de raízes de cana-de-açúcar a partir da contagem de intersecção de raízes na parede do perfil RESUMO: A densidade de comprimento de raízes (DCR) é uma característica importante para determinar o potencial de absorção de água e nutrientes das plantas, mas é difícil de ser medida. Nenhum método padrão está atualmente disponível para avaliar a DCR no solo. Neste estudo, um método in situ usado em outras culturas para estudo da densidade de comprimento e distribuições das raízes foi testado para a cana-de-açúcar (Saccharum spp.). O método envolveu contagem de intersecções de raízes (CIR) no perfil de um Latossolo Vermelho eutroférrico, usando grade com quadrículas de 0.05 × 0.05 m, modelizando a DCR a partir da CIR. Os resultados foram comparados com o método do trado cilíndrico (TRA) (volume de 0.00043 m -3 ). Em quatro épocas durante o ciclo em três manejos do solo (plantio convencional, cultivo mínimo e plantio direto), em oito profundidades divididas a cada 0.1 m (entre 0 -0.6 e 1.6 -1.8 m) e três distâncias horizontais em relação à linha de plantio (0 -0.23, 0.23 -0.46 e 0.46 -0.69 m), os métodos TRA e CIR apresentaram resultados...

Root growth and distribution in sugarcane cultivars fertigated by a subsurface drip system

“…Both studies were carried out without irrigation, but only Otto et al (2009) have reported more than 80% of root mass up to 0.4 m depth. Despite of not showing the relative values, Azevedo et al (2011) and Laclau & Laclau (2009) also found higher root density up to 0.4 m depth. Typical values for sugarcane root mass up to 0.2 and 0.6 m depth are 50% and 85%, respectively (Smith et al, 2005).…”

“…Although Azevedo et al (2011), Laclau & Laclau (2009), Otto et al (2009 and Vasconcelos et al (2003) have studied sugarcane root system, they used other methods, which difficult the comparison based on the value itself. However, all of them reported large variability for root evaluations such as root mass and length.…”

“…When considering samplings along the crop cycle, the data is even scarcer. Azevedo et al (2011) have tested the root intersection counting combined with the soil core-sampling method in three sugarcane growth stages, whereas Laclau & Laclau (2009) have used the intersection counting method at the end of crop cycle and used the soil core-sampling method to assess the root development along the cycle in six growth stages. Unfortunately, there is no recent data about the assessment of sugarcane root system using non-destructive methods, such as minirhizotrons, which allow the monitoring of root growth along the crop cycle under field conditions.…”

Soil physical attributes and productivity of sugarcane under different cropping systems in the savannah goiano

“…Azevedo (2008) and Azevedo et al (2011), evaluating soil tillage in sugarcane root study also detected no difference between different types of preparation. While Mello Ivo and Mielnickzuc (1999), working with the corn crop in three different soil preparation, identified a higher density of roots in the 0.0 -0.05 m in no-tillage system, while in the conventional tillage system that occurred in layer below 0.10 -0.15 m.…”

“…These actions provided a better environment for the development of roots due to pH correction of the soil, favoring aeration and improved water distribution in soil profile. In a similar study evaluating root length density and distribution of sugarcane roots by counting the roots from the intersection with the profile wall in three tillage systems, Azevedo et al (2011) observed that the greatest root length density in the soil occurred in the area where the soil preparation was done with plowing + harrowing, in the layer between 0.00 and 0.20 m with the greatest concentration of roots in the row. However they observed few differences between the treatments in the inter-rows of sugarcane.…”