Yield and yield attributes of durum wheat genotypes as affected by boron application in boron-deficient calcareous soils: An evaluation of major Turkish genotypes for boron efficiency

Field studies were conducted to determine yield and yield attributes of six durum wheat (Triticum durum Desf.) genotypes namely; Kiziltan-91, Ç-1252, Selçuklu-97, Kunduru-1149, Yilmaz-98, and Çakmak-79, as affected by applications of different levels of boron (B) (0, 1, 3, and 9 kg B ha-1 delivered as boric acid, H 3BO3) in soils deficient in available B (0.19 mg B kg -1) and high in lime (CaCO3) content (20.7%) during two consecutive growing seasons; 2000-2001 and 2001-2002. Agronomic characteristics such as grain yields, spike sterility rates, number of grains per spike, number of spikelets per spike, number of spikes per m2, grain weight per spike, thousand grain weights, test weights, and flag leaf B concentration were investigated. Grain yields in all genotypes were significantly increased by B applications compared to the control. Applications of 1 and 3 kg B ha -1 increased yield an average of 11 and 9% respectively, while 9 kg B ha-1 resulted in lower overall yield increase (7%). Genotypes studied have shown significant variations with respect to their responses to additional B. Kunduru-1149 and Çakmak-79 gave the highest grain yield (4080 and 4315 kg ha-1 respectively) at 1 kg B ha-1, whereas Kiziltan-91 and Yilmaz-98 yielded best (4475 and 5010 kg ha-1 respectively) at 3 kg B ha-1. Interestingly, other two genotypes, Ç-1252 and Selçuklu-97, reached to the highest level of grain yield (4320 and 4360 kg ha-1 respectively) at the highest B level (9 kg ha-1). Yield attributes also showed significant variations with respect to their responses to B application. Kiziltan-91 and Kunduru-1149 appeared to have high sensitivity to B deficiency. On the other hand, Çakmak-79 and Selçuklu-97 were B deficiency tolerant genotypes. The study clearly showed that B deficiency could result in significant yield losses in durum wheat under experimental conditions tested. Hence, B contents of soils for the cultivation of durum wheat should be analyzed in advance to devoid of yield losses. Plant tissue analyses can also result in grain yield predictions. Genotypes proven as tolerant/sensitive to high/low B levels may offer valuable genetic materials for use in B-related breeding programs. Considering relationships between flag leaf B concentrations and grain yield, it was clear that when climatic conditions (second year) suit wheat cultivation, B application in B-deficient soils can make profound contributions to grain yield in wheat compared to adverse climatic conditions (first year). Clear positive contribution of B application to grain yield in durum wheat can be more evident under better climatic conditions.