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ARS Home » Research » Publications at this Location » Publication #63067


item Sinclair, Thomas

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/26/1996
Publication Date: N/A
Citation: N/A

Interpretive Summary: The centuries-old practice for wheat production in arid regions is the use of a fallow management. In fallow management a crop is grown in alternate years and the land is kept bare in intervening years. The original hypothesis was that water would be stored in the fallow season for use by the succeeding crop. In fact, recent evidence indicates that in the wheat-production regions of Israel water is rarely stored for use by the crop. The main benefits appears to be a "sanitization" of the soil in the fallow season. This paper explores the possibility that the cereal cyst nematode (CCN) populations which damage wheat plants, are depleted in the fallow year allowing subsequent crop production. Both controlled-environment and field studies are reported to show the nature and extent of CCN damage on wheat crops. The effect of CCN damage on crop water use are also reported.

Technical Abstract: Wheat (Triticum aestivum L.) is grown in many arid regions using fallow management. Although fallowing is commonly thought to be important in increasing the availability of water and nitrogen to the wheat crop, experiments in Israel showed that water carryover from the fallow season was rare. This paper examines the possibility that the benefit of fallowing may be to sanitize the soil of cereal cyst nematode (CCN, Heterodera avenae Woll.) because of the severe damage inflicted on wheat growth. Pot experiments in controlled environments showed a dramatic and quantitative, negative effect of various populations of CCN on wheat root growth. The decrease in root growth was associated with decreased shoot growth and decreased rates of transpiration. Mechanical pruning of roots mimicked the effects of CCN infestation indicating that root pruning was the primary damage of CCN. Results from field studies showed that dry weight yields were maintained even in continuous wheat management when a soil biocide was used to eliminate CCN. It is proposed that CCN cysts hatch in the wet soil of the fallow year but fail to produce a new generation of cysts because no host plants are present. Curiously, in one season with high amount of precipitation CCN damage on continuous wheat was eliminated even with no biocide application.