Publications

Evaluation of critical phases of sulphur supply for optimum yield and quality of wheat


HGCA PROJECT REPORT 272

EVALUATION OF CRITICAL PHASES OF
SULPHUR  SUPPLY FOR OPTIMUM YIELD
AND QUALITY OF WHEAT



by

M J Hawkesford, R V Palmer, F J Zhao and S P McGrath

IACR Rothamsted, Agriculture and Environment Division
Harpenden, Hertfordshire, AL5 2JQ 

FEBRUARY 2002

Abstract

This project combined an agronomic study of optimum timing for S-fertilizer application with physiological and biochemical approaches to investigate sulphur metabolism in wheat. The major applied aim was to determine the optimum window for spring S-application and to provide this information as a guideline for levy payers.

 In field trials undertaken in two successive years, S was applied to a winter wheat crop on a known deficient site at 4 different times throughout the spring/early summer seasons. S-application (30 kg/ha) as sulphate (gypsum) to the soil had a remedial effect of increasing yield by 30% in 2000 and by 40% in 2001. Application was effective when applied between March and May (GS 13 to 31). Application after GS 39-59 in June failed to increase grain yield.

 Application of S-fertilizer also influenced grain S-concentrations, irrespective of application date (March to June, GS 13-59). Analysis of the grain from all plots receiving S-application indicated that grain S concentration was increased from 0.83 to around 1.2 or from 0.99 to 1.57 mg g-1 DW in 2000 and 2001, respectively. Grain nitrogen was not affected by S-fertilizer application, however N:S ratios were decreased from around 25 to below or equal to 17 by S-application. A direct consequence of the S-concentration was a modification of the protein profiles and the amino acid composition.

In glasshouse experiments in which wheat was grown on nutrient solution and continuously supplied with S at five rates, grain yield was maximal at supply rates of 0.1 mM ('adequate') to 5 mM ('substantially well-fertilized'), but decreased at rates above this. Grain sulphur ranged from 2.1 to 2.9 mg g-1 over a range of S-supply from adequate (0.1 mM in solution) to a substantial excess (20 mM).

These high S-concentrations most likely result from the continuous supply of S throughout all growth stages which is beneficial compared to the single dose usually applied in the field. S is required for optimal vegetative development (hence a requirement for early season application) and for grain S accumulation (which may require a subsequent application). In all cases unassimilated inorganic S was present in the grain, and this greatly increased with increasing levels of supply. This represents an un-exploited resource, potentially available to improve quality parameters.



HGCA Project Number: 1919
Price: £4.30

Related Publications

Document download

View a printer friendly version of this publication

Download this publication PDF
Project_report_thumb