Chloride by Variety Interactions in Spring Wheat
Chloride is known to suppress several wheat diseases or increase the ability of wheat to withstand infection. Wheat response to chloride fertilizer has been variable, because response depends upon many factors, including soil chloride levels, pH, plant tissue levels, and variety.
IPNI-1996-USA-ND9
15 Mar 2001
Justification
- Chloride is an essential nutrient for plant growth and metabolism. The roles of chloride in plant nutrition could be divided into "essential" roles and "helpful" roles. the essential role of chloride in plant metabolism involves photosynthesis. Chloride is essential for the functioning of chloroplasts. Grown in the total absence of chloride, plant tissues cannot photosynthesize.
The "helpful" role of chloride in plant metabolism involves the maintenance of turgor in the plant. Plants maintain a positive turgor pressure by the accumulation of salutes, primarily in the central vacuole of the plant cell. These solutes can include non-ionic substances like sugars, or ionic substances like K+, malate-, and Cl-. A comprehensive review of chloride in crop nutrition has recently been published (Fixen, 1993).
In the Great Plains, well-drained soils are often very low in chloride. Common minerals in our soils do not weather to yield chloride. The chloride content of our rainfall in North Dakota is very low. Organic matter in our soils is not a source of chloride. thus, the major sources of chloride in our soils, apart from the small amounts in the rainfall, are application of chloride-containing fertilizers (primarily KCl) and chloride salts present in water tables and poorly-drained soils.
Wheat and barley have been shown to respond to chloride fertilization in the Great Plains and soil test and plant analysis critical levels have been established (Engel and Grey, 1991; Engel et al., 1992; Fixen et al., 1986a; Fixen et al., 1986b; Fixen et al., 1987; Goos et al., 1987; Goos et al., 1998; Timm et al., 1986.
One area needing further research is the classification of wheat varieties with regards to responsiveness to chloride fertilization. Variety x chloride interactions have been shown many times. For example, the common variety 'Marshall' has responded reliably to chloride fertilization on low Cl soils in South Dakota, whereas the variety 'Guard' (a specialty variety grown for Hessian-fly resistance) did not respond to chloride in the same trials. Similar interactions have been found for Canadian spring wheat varieties and for U.S. malting barley varieties (Fixen, 1993).
Research in Montana has also shown strong variety x Cl interactions for winter wheat. Varieties have been shown to differ dramatically, not only in terms of yield response to chloride fertilization, but also with regards to expression of a physiological leaf spot or necrosis, which is probably a valid Cl deficiency symptom (Engel et al., 1996).
Variety x Cl research has shown strong interactions in wheat. Unfortunately, little is know about the Cl responsiveness of the current mix of varieties grown by farmers in this region. The Foundation of Agronomic Research (FAR) desires to sponsor a regional series of trials, in North Dakota, South Dakota, Manitoba, and possibly other areas, to categorize spring and winter wheat varieties with regards to response to chloride fertilization. The purpose of this proposal is to apply for funds for trials in North Dakota.