Leaf Area and Dry Matter Accumulation of Wheat Following Forage Removal1
- D. J. Dunphy,
- E. C. Holt and
- M. E. McDaniel2
Wheat (Triticum aestivum L. em Thell.) is commonly both grazed for forage and harvested for grain in the Southern Great Plains of the USA. Information is needed on the plant characteristics affected by forage removal and their relationships to grain yield. Leaf area index was measured at 0,1, and 2 weeks following forage removal in 3 years of field experiments. The soil type was a member of the fine, montmorillonitic thermic family of Vertic Albaqualfs. Leaf area and dry matter present at anthesis were also recorded. Treatments consisted of taking the final forage harvest for two cultivars at the early joint, mid-joint, or late joint stage of development but without removing terminal meristems. All treatments were harvested for grain at maturity, including a check that was not harvested for forage. Total LAI at anthesis averaged over varieties for the first 2 years, decreased from 1.40 to 0.79 when the final forage harvest was delayed from early to late joint. Total dry matter present at anthesis averaged over all years and varieties decreased from 491 to 326 g m−2. Leaf area duration from jointing to anthesis, the product of the average leaf area present and the number of days in the sampling period, averaged 42.9 days m2m−2 for the early joint treatment, compared to 15.8 days m2m−2 for the plants harvested at late joint. These factors were highly correlated (r = 0.64 to 0.88) with grain yield in all 3 years for both cultivars. The data indicate that when the leaf area produced during the vegetative and jointing stages was harvested as forage, grain yield was limited by the potential of the plant to rapidly produce new leaf area and prevent tiller senescence during the period between jointing and anthesis.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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