The effects of nitric oxide pollution on the growth of tomato

Abstract

Nitric oxide is the predominant air pollutant in glasshouses in which hydrocarbons are burnt to provide heating or CO₂ enrichment of the atmosphere. Some circumstances in which this pollution can increase or reduce the growth of tomato Lycopersicon esculentum Mill. have been identified. A factorial experiment involving varied levels of soil fertility showed that when the amount of nitrogen available in the soil is low, the plants can tolerate, and even benefit from, nitric oxide in the atmosphere. Even at low levels of soil nitrogen there are, however, deleterious effects of the pollutant if its concentration rises above a critical level; under the conditions of the experiments reported in this paper this level was between 40 and 80 pphm.

The response to nitric oxide differs markedly among varieties of tomato. One modern F₁ hybrid (Sonato) was greatly stimulated in its growth by 40 pphm nitric oxide. This may explain the success of this variety in commercial glasshouses that are normally polluted with nitric oxide during CO₂ enrichment.