This paper presents results investigating the variation in cotton plant’s growth responses to soil water status with different soils types. Such information is necessary to optimise irrigation strategies. Field experiments were conducted on three soil types around Narrabri NSW Australia with plant available water holding capacities ranging from 60 to 200mm. To assess plant response
to moisture stress two treatments were also imposed (no stress (no irrigations missed) and stress applied during the period immediately prior to and during flowering
(skipping two irrigations)). Measurements of soil water status and leaf water potential (used as an indication of the level of plant stress) were taken during the imposed stress in both stress treatments and throughout the recovery period. To compare data across the three soil types soil moisture measurements were expressed as a fraction of transpirable soil water (plant available soil moisture/plant available water holding capacity).
The response of plants to soil moisture stress across the three soil types was different with the lighter soil (the one with lowest soil water holding capacity) exhibiting greater plant stress at all levels of soil water status. These results highlight the need to establish specific soil moisture stress responses for different soil types. There were strong indications that high evaporative demand was a strong factor in determining leaf water potential, especially in light soils. This research forms part of detailed investigations into soil moisture plant stress responses with prevailing climatic conditions had a large effect on the ability of the plant maintain water status even under low levels of soil moisture deficit, on high evaporative demand days plants often experienced stress which had an impact on yield despite a high proportion of water still being available in the profile.
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