Necdet Akgün

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

Abstract Field studies were conducted to determine yield and yield attributes of six durum wheat (Triticum durum Desf.) genotypes namely; Kızıltan-91, Ç-1252, Selçuklu-97, Kunduru-1149, Yılmaz-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, H3BO3) 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 Kızıltan-91 and Yılmaz-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. Kızıltan-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.

Efficiency of Topdressed Nitrogen Sources and Application Times in Fallow-Wheat Cropping System

Yield and quality of bread wheat in dry farming can be significantly affected by environmental conditions and fertilizer applications. This study was conducted to determine the effect of year, nitrogen (N) sources and topdressed times on the grain yield and quality traits of bread wheat (Triticum aestivum L.) in a fallow-cereal system in calcareous soils over two years, 1995/96 and 1997/98, in Central Anatolia. Three N sources, urea, ammonium nitrate (AN) and ammonium sulphate (AS), were applied as hand broadcast on the soil surface during spring at four different times. Timing and N rate applications including; 0 kg N ha−1 (N0), 40 kg N ha−1 at early spring (NE), 40 kg N ha−1 at late spring (NL), and a split application of 20 kg N ha−1 at early and 20 kg N ha−1 at late spring (NEL). The traits investigated were grain yield, protein content, protein yield, 1000 kernel weight and grain size. Effects of year (Y), N source (N) and timing (T) on yield and quality traits differed significantly. While grain and protein yield were significantly affected by Y x N x T interaction (p<0.05), protein content, 1000 kernel weight and grain size were significantly affected by Y and T (p<0.01). Y2×urea×NE gave the highest grain yield (2.78 t ha−1) while the highest protein yield (0.31 t ha−1) was obtained from Y1×urea×NEL interaction. Overall topdressed urea increased grain and protein yield more than similarly applied AN and AS. Spring applied topdressed N increased grain yield and protein yield, but decreased 1000 kernel weight and grain size (>2.5 mm).

Yield and Yield attributes of Durum Wheat (Triticum durum Desf.) as Affected by Boron Application

Boron (B) deficiency causes grain set in bread wheat to fail (Rerkasem and Jamjod, 1997). Rarkasem et al. (1993) reported that B deficiency lowered the number of grains per spike and grain yield in wheat via suppression of the growth of flowering organs. In another study, Rerkasem et al. (1997) found that B deficiency clearly depressed seed yield, number of grains per ear, and grain set index of bread wheat, without any apparent effect on number of ears per m2, number of spikelets per ear, average size of the ear, and component florets per spikelet. Boron deficiency was considered to be the main reason for sterility in susceptible wheat genotypes since B application reduced sterility from 42.6 to 4.5 % (Subedi et al., 1997). Since B has important effects in pollen tube elongation, and on pollen grain germination and growth (Dickinson, 1978), the main effects of B deficiency are usually expressed during generative development rather than in vegetative plant parts (Rerkasem and Jamjod, 1997; Huang et al., 2000).