Gas sampling next to tomato cultivars

Cultivar diversity of processing tomato increases ecosystem functions and services.

Felipe Barrios Masias, Louise Jackson This project focuses on the understanding of some of the ecological processes that are related to the increase of cultivars within a processing tomato field. The processes under study are:

• plasticity of a given cultivar 'AB2' under different community composition of other tomato cultivars
• resource utilization  
• stability over different environmental stresses  
• efficiency on N utilization as a limiting nutrient in organic systems  

An experimental area was established in Fall 2005 with fallow and mustard cover-crop plots, following in the spring with sub-plots of 1, 3 and 5 tomato cultivar mixtures. Soil, at three different depths, and aboveground biomass samplings have been collected continuously through the study for determination of nutrient utilization. Analyses for NO₃^-, NH₄⁺, potentially mineralizable N and microbial biomass C have been performed as well. Lysimeters for NO₃^- content of water leaching below 60 cm were also used. Other evaluations for assessing cultivar phenotypic responses and contributions to plant community were: CO₂ and N₂O gas emission after irrigation, canopy light interception, disease presence, and yield.