Zeinab M. Khalil, Manal F. Tantawy and M. A. H. Mohamad( 2015). Effect of cobalt applications on yield and yield components of wheat grown under two intervals of irrigationMinufiya J. Agric. Res. Vol.40 No. 1(2): 239 - 261 (2015)
Abstract: A field experiment was carried out on a clayey soil at El-Gemeiza Agricultural Research Station, El-Gharbia Governorate, Middle Nile Delta region, Egypt during two successive growing winter seasons of 2012 / 2013 and 2013 / 2014 to study the effect of different rates and doses of cobalt and its temporal foliar application on growth, yield and some chemical compositions of wheat plant ( Triticum aestivum L.) variety Gemeiza 11 under two intervals of irrigation; 25 and 40 days. Cobalt was added as Co- acetate {(CH3COO)2 Co} at four rates namely 81, 162, 324 and 648 mg Co / L in addition to control treatment with Co-free water on two techniques; the first was three equal doses at seedling, tillering and heading stages and the second was one dose only at tillering stage. The volume of the spray solution for each application was 400 l / fed. The experiment was carried out in a split split plot design with three replicates. The obtained results showed that:-
Plant height (cm), spike length (cm), number of spikes / m2, weight of 1000 grains (g), grains and straw yields as (kg/plot and kg/fed.) as well as biological yield (kg/fed.) were significantly increased with the increase of added Co rate. Foliar application of Co on three equal doses efficiently enhanced these parameters more than those sprayed on one dose. Also, the values of the previous parameters were markedly higher when wheat plants irrigated every 25 days than those irrigated every 40 days. The best results were accompanied with the foliar application of Co at a rate of 648 mg Co / L, applied on three equal doses, under 25-day irrigation interval treatment. Interaction effects among all the applied treatments were insignificant on the studied parameters of plant growth, grains and straw yields and yield quality. Also, most of the dual interactions exerted significant effect on growth characters. However, the interaction between the techniques of Co application rates and doses was significant effect on grain and straw yields. Nitrogen, P and K concentration (%) and uptake (kg / fed.) by grains and straw as well as crude protein (%) were increased by elevating Co rates especially in the first technique of Co application and at 25-day irrigation interval. Nitrogen and P concentration (%) and uptake (kg / fed.) by grains were higher than those by straw, while K appeared reverse this trend.
Except Fe, both concentrations (mg kg-1) and uptake (g / fed.) of Mn, Zn, Cu and Co by grains and straw were increased with the increase of added Co rates, especially in the first technique of Co application and at irrigation every 25 days. The obtained data exhibited existence of an antagonistic relationship between the added Co and Fe. These microelements could be arranged, according to their contents of both grains and straw, in the following orders: Fe > Zn > Mn > Cu > Co. Except Zn, the content of the microelements, under study, in grains were higher than those found in straw.
Keywords: (Clayey soil, Irrigation intervals, Cobalt, Foliar application, Rates, doses, Wheat productivity, quality. )
