Assessment of grain set failure and diagnosis for boron deficiency in wheat
1990
Rerkasem, B. | Lodkaew, S. | Jamjod, S. (Chiangmai University, Chiangmai (Thailand). Faculty of Agriculture, Multiple Cropping Centre)
This poster presents some information on the assessment of grain set failure and diagnosis of boron (B) deficiency in wheat. Basal floret fertility (average number of grains in the two basal florets, F1+F2, of 10 central spikelets) is proposed as an index for assessment of grain set failure. The index correlated well with overall floret fertility ( fully developed florets with grain, R2 = 0.95) and spikelet fertility (number of grains/spikelet relative to the maximum, R2 = 0.91) in several wheat genotypes grown in the field and sand culture. The maximum number of 1.9-2.0 grains/F1+F2, constant over genotypes and conditions, is a built in reference that allows the index to be used in farmers' fields and other situations in the absence of a no-sterility control. The reduction or elimination of grain set failure by B application has been the basis for diagnosis of B deficiency as the cause of sterility in Brazil, China, Thailand, and Nepal. Soil and plant tissue analyses are additional diagnosis tools, but there are some difficulties with both for B deficiency in wheat. Soil analyses for available B gave varying results, with sterility observed in soil with 0.18 to 0.52 mg B/kg in China and less than 0.15 mg B/kg in Thailand. The reduction in the number of grains/spikelet by B deficiency in a soil with a given level of hot water soluble B varied with wheat genotypes and sowing dates. Well defined relationships between leaf B concentrations and grain set failure were found for SW41 and other wheat genotypes sensitive to B deficiency; more tolerant genotypes did not fit into the same relationships
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