Agroclimatic classification: numerical- taxonomic procedures - a review.

The paper catalogues the procedures and steps involved in agroclimatic classification. These vary from conventional descriptive methods to modern computer-based numerical techniques. There are three mutually independent numerical classification techniques, namely Ordination, Cluster analysis, and Minimum spanning tree; and under each technique there are several forms of grouping techniques existing. The vhoice of numerical classification procedure differs with the type of data set. In the case of numerical continuous data sets with booth positive and negative values, the simple and least controversial procedures are unweighted pair group method (UPGMA) and weighted pair group method (WPGMA) under clustering techniques with similarity measure obtained either from Gower metric or standardized Euclidean metric. Where the number of attributes are large, these could be reduced to fewer new attributes defined by the principal components or coordinates by ordination technique. The first few components or coodinates explain the maximum variance in the data matrix. These revided attributes are less affected by noise in the data set. It is possible to check misclassifications using minimum spanning tree.

Sunflower and peanut emergency : initial development under sugarcane mulch.

The research aimed to evaluate the effect of residual sugarcane mulch on sunflower and peanut plant emergence and initial development. Vases of 4.0 L were disposed in a randomized experimental blocks design, with four replications, in a factorial arrangement of five mulch amounts and three cultivars of each crop. The mulch treatments consisted of four increasing amounts (5, 10, 15 e 20 t ha-1) and a tester with no mulch. The sunflower cultivars were the varieties IAC-iarama and Catissol and the hybrid H-358; the peanut cultivars were IAC-Caiapó, Runner 886 and Tatu. The speed emergency index and final percentage, the plant height and shoot dry mass were evaluated. The presence of different levels of sugarcane mulch negatively influences the emergency and initial plant development mainly in peanut but also in sunflower. The negative effects are stronger especially for the runner type of peanut cultivars, while cultivar Tatu was less influenced by the mulch thickness.