Mateus Carvalho Basílio de Azevedo

Estimating sugarcane root length density through root mapping and orientation modelling

Root length density (RLD) is a key factor in crop functioning. A field method was developed to quantify RLD of sugarcane from root intersection density (RID) taking root orientations into account. RIDs were observed on three perpendicular soil planes and RLD was measured for the enclosed volume. RID and RLD of thick and fine roots were measured separately. These measurements were replicated at different ages and sites to test models describing RLD according to RID. Fine roots were nearly isotropic and thick roots had a preferential orientation, i.e. horizontal near the surface and becoming progressively vertical in deeper horizons. Relationships in thick roots were modelled according to COt: RLDt = RIDt. COt (COt: root orientation coefficient, ranged from 1.3 to 4.9 for thick roots). For fine roots (f), COf = 2. This theoretical model led to differences between measured and calculated RLD. The ratio between measured and calculated RLDf (CEf) increased from 1 to 3 with RIDf. CEf was introduced as an additional coefficient in the model: RLDf = 2. NIf. CEf. Intermediate results were obtained for all (a) roots: COa and CEa were both dependent on RIDa, therefore: RLDa = NIa. COa. CEa. The models were validated with independent datasets from Brazil and France. These allowed a more robust prediction of RLD than direct regressions between RID and RLD. They may estimate RLD from RID in soil profiles by root mapping while taking RLD spatial variability into account.

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

A densidade de comprimento de raizes (DCR) e uma caracteristica importante para determinar o potencial de absorcao de agua e nutrientes das plantas, mas e dificil de ser medida. Nenhum metodo padrao esta atualmente disponivel para avaliar a DCR no solo. Neste estudo, um metodo in situ usado em outras culturas para estudo da densidade de comprimento e distribuicoes das raizes foi testado para a cana-de-acucar (Saccharum spp.). O metodo envolveu contagem de interseccoes de raizes (CIR) no perfil de um Latossolo Vermelho eutroferrico, usando grade com quadriculas de 0.05 x 0.05 m, modelizando a DCR a partir da CIR. Os resultados foram comparados com o metodo do trado cilindrico (TRA) (volume de 0.00043 m-3). Em quatro epocas durante o ciclo em tres manejos do solo (plantio convencional, cultivo minimo e plantio direto), em oito profundidades divididas a cada 0.1 m (entre 0 - 0.6 e 1.6 - 1.8 m) e tres distâncias horizontais em relacao a linha de plantio (0 - 0.23, 0.23 - 0.46 e 0.46 - 0.69 m), os metodos TRA e CIR apresentaram resultados de DCR similares. Encontrou-se positiva entre TRA e CIR (R2 = 0,76). As DCRs nos perfis, considerando as medias das tres distâncias da linha por profundidade, obtida utilizando-se de TRA e CIR (media de quatro datas e 12 repeticoes), foram proximas e nao diferiram a cada 0.1 m de profundidade ate 0.6 m de profundidade. A DCR total entre 0 e 0.6 m foi de 7.300 e 7.100 m m-2 para TRA e CIR, respectivamente. Para o tempo de realizacao, o metodo CIR foi 10 vezes mais rapido do que TRA e o metodo CIR pode ser realizado no campo, sem necessidade de remover amostras de solo. A distribuicao da DCR em profundidade e distância da linha (variabilidade 2D) pelo metodo CIR pode ser avaliada em relacao as propriedades do solo nos mesmos perfis do solo. O metodo CIR foi apropriado para estudos dessas relacoes 2D (profundidade e distância da linha no perfil do solo) entre solo, manejo e distribuicao de raizes no campo.

INFLUENCE OF SEEDLING PRODUCTION METHOD ON THE ROOT SYSTEM DISTRIBUTION OF BLACK WATTLE TREES

The purpose of this study was to evaluate the root system distribution of three-year-old black wattle (Acacia mearnsii) trees. The plants were originated from seedlings grown in different containers and planted in an Argisol in the state of Rio Grande do Sul, Brazil. The containers used for seedling production were: wood laminated pots, round plastic tubettes and styrofoam trays. The evaluations were carried out using the trench profile method up to 1 m depth on tree rows and inter-rows. The following soil analyses were also carried out: bulk density, total porosity and pore distribution. The type of container used influenced the development of the root system of trees on the field. Wood laminated pots were better than the round tubettes for root length in the tree rows. The roots developed better on the tree rows where soil density and porosity conditions were more adequate.

Enraizamento de estacas herbáceas dos porta-enxertos de videira Campinas (IAC 766) e Jales (IAC) 572 em diferentes substratos

This research was an attempt to evaluate the herbaceous cutting rooting of two vine rootstocks (‘Campinas’ - IAC 766 and ‘Jales’ - IAC 572) on three types of plant growth medium (hull rice coal, vermiculite - small granules and vermiculite - medium granules). Cuttings were taken from a virus-free stock plant, through the removal of green branches. Firstly, preparation of cuttings consisted on the elimination of the leaves of the basal portion, leaving one leaf in the superior part of each one. After that, the cuttings were placed in plastic boxes containing different types of growth medium on mist chamber. A randomized design was used as statistical model with 6 treatments and 5 replications. Each plot was composed of 10 cuttings. Once the proper rooting was observed, the effect of roostock and growth medium was evaluated. It was possible to conclude that: a) the average porcentage of rooted rootstocks on the different growth medium is high (90%); b) hull rice coal provides the best results for cutting rooting for both rootstocks; and c) ‘Campinas’ rootstock is superior than ‘Jales’ regarding the number of roots per cutting and the root system weight.

Desenvolvimento de mudas de aceroleira propagadas por estacas e sementes em solo compactado

The objective of this research work was to evaluate West Indian Cherry (Malpighia emarginata D.C.) above-ground and root system development, in plants propagated by seeds and cuttings at different soil density levels ( 1,0; 1,2; 1,4 and 1,6kg dm-3). The experiment was carried out in pots with 200 mm diameter and 285 mm height, divided in three rings with 100, 35 and 150 mm height. The experimental design was totally randomized in a factorial arrangement 2 x 4 (two propagation forms and four soil densities) with five replications. The increase in soil density improved a higher above-ground parts and roots development in plants propagated by cuttings. Independent of the propagation method, the studied soil density levels did not prevent the root penetration.