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Explaining variation in the effects of take‐all ( Gaeumannomyces graminis var. tritici ) on nitrogen and water uptake by winter wheat
Author(s) -
Pillinger C.,
Paveley N.,
Foulkes M. J.,
Spink J.
Publication year - 2005
Publication title -
plant pathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.928
H-Index - 85
eISSN - 1365-3059
pISSN - 0032-0862
DOI - 10.1111/j.1365-3059.2005.01229.x
Subject(s) - take all , biology , agronomy , crop , nitrogen , growing season , field experiment , soil water , fungicide , canopy , horticulture , zoology , botany , chemistry , ecology , fungus , organic chemistry
Two field experiments, in 1999 and 2000, were used to test whether reductions in root growth and function explained the effects of take‐all on crop water and nitrogen uptake. The fungicide silthiofam was used to manipulate take‐all independently of other factors. Soil water content was manipulated from heading to determine effects on disease progress and resource capture. Epidemic progress was significantly delayed in the presence of silthiofam, leading to reductions in disease in both experiments. Effects of silthiofam were reduced by increasing soil water late in the season, although only in 2000 did increased soil water content have a direct effect, leading to a higher rate of disease increase. Higher levels of disease in the absence of silthiofam did not affect root growth as measured by total root length density (TRLD), but did lead to significantly reduced healthy root length density (HRLD, a measure of functional roots) in both experiments. Only in 2000 were there any significant effects of increased take‐all on water and nitrogen uptake. This was attributed to the higher TRLD in the (1999) crop, which allowed HRLDs to be maintained above a critical threshold (where water and nitrogen uptake start to be severely affected) despite loss of functional root to disease. The effects of take‐all on nitrogen uptake were more likely to affect crop canopy size and duration than the relatively small effects observed on water uptake. Increasing soil water content allowed the crop to take up more water in absolute terms despite, in 2000, increasing levels of disease and reducing HRLD.