The inappropriate use of herbicides has increased the resistance of weeds; thus, the study of allelopathy becomes of paramount importance. The ability of certain plants to interfere with the metabolism of others by means of substances released into the environment, either by their aerial or roots system, becomes an alternative to combat invasive plants, dispensing with or reducing the use of herbicides. The objective of this work was to evaluate the plant species most sensitive to the allelopathic potential of aqueous extracts. One of the plant species studied was lettuce because it had a rapid response potential, thus showing the benefits obtained through allelopathy.

Proper handling of the wheat crop is crucial to obtain the full expression of the genotype potential. Among the various management techniques, the spatial distribution of plants and the disposal of the same plant in agriculture deserve attention. It is known that the distribution may alter the productivity; however, it is uncertain, the technological changes it might entails. With this in view, the aim of this study was to evaluate in two wheat cultivars, characteristics of agronomic interest and the technological quality of flour depending on the spacing. The experimental design was a randomized block with four replications in a factorial 4 × 2. The first factor refers to the spacing: 20, 28, 36 and 40 cm and the second factor refers to the cultivars:CD 150 and BRS Tarumã. The experiment was carried out in Santa Tereza do Oeste, western region of Parana state, in May 2011. The yield and grain moisture were reduced with increased spacing of 3.98 and 26.18%. The hectolitre weight, thousand grain weight, the moisture of the flour, ash content dry basis, the falling number, and flour color were not affected by increasing spacing. Cultivar CD 150 presented lighter color, higher weight hectolitre, lower ash content and fewer drop from the BRS Tarumã.