The influence of environmental factors and agricultural practices on wheat falling number

Various environmental factors together with agricultural practices by producers that might contribute to reduced Hagberg Falling Numbers (HFN) of wheat, Triticum aestivum, in the absence of pre-harvest sprouting were simulated to determine whether HFN could be managed through specific management practices. Sufficient data have been generated to recommend that wheat should be allowed to dry to acceptable levels before they are harvested. Alpha-amylase activity could, however, not be successfully linked to reduced HFN at high kernel moisture content (KMC). Glyphosate treatments, administered at soft and hard dough stages to induce dry down of kernels at various KMC, produced more stable HFN for two of the three cultivars evaluated, but the optimal physiological growth stage resulting in the most stable HFN varied over seasons. Fifteen South African wheat cultivars were subjected to evaluation for their HFN response to various degrees of fertilizer application. No statistically significant effect on the HFN of wheat in general could be made. Cultivar differences did, however, occur that allowed for the individual effect of fertilizer on the HFN of these cultivars to be identified. This allowed for the grouping of cultivars into four response groups namely low, low to medium, medium and high response cultivars. Classification was refined with the use of a CVA (canonical variate analysis) that included the HFN, yield and protein response to fertilizer application. Recommendations regarding cultivar choice in areas prone to leaching can therefore be limited to cultivars that fall into the low and low to medium response groups identified in this study. Moderately high temperature exposure (32°C) during various grain filling stages of wheat resulted in reduced HFNs being measured. The physiological growth stage most affected by such temperatures, however, varied between cultivars. Further studies are suggested. In addition, farmers in areas that are known for their late frost should avoid planting early, as a study into the effect of a single night of low temperatures (–4°C) at late milk stage indicated that HFN could, as a result, be significantly reduced. A screening protocol was accordingly created to screen all cultivated varieties for such reactions, so that recommendations could be made as to which cultivars would be more tolerant to such conditions.