Response of wheat 'Triticumaestivum L.' to humic acid and organic fertilizer application under varying Siwa Oasis conditions

A field experiment was carried out at Siwa Oasis, Matrouh governorate, during 2012/2013 growing winter season, to study the response of wheat (Triticumaestivum, L.) cv. Sakha 94, to applications of humic acid rates (8.3, 10.7 and 13.1 kg/ha) and organic fertilizer rates (35, 47.5 and 60 m 3 /ha) under varying Siwa conditions. The most important results are summarized as follows:1) Variation in soil salinity had an impact on studied characters, especially those subjected to combined analysis over locations. 2) Spike length, no. of spikelet/spike and 1000-grain weight were increased with increasing both organic and humic acid rates in the three locations. 3) The data for combined analysis showed significant differences between locations, organic fertilizer rates and applied humic acid rates for plant height, no. of spikes/m 2 , no. of grains/spike, biological yield and harvest index. 4) Location 2, with lowest E.C. values gave significantly higher values for plant height, biological yield, grain yield and yield components, i.e. number of spikes/m 2 and number of grains/spike, and harvest index compared to location 1 and 3. 5) Increase in grain yield reached 7.1 and 13.6 % by increasing humic acid rate from 8.3 to 10.7, and from 8.3 to 13.1, respectively.