This research was carried out in experimental field of Field Crops Department of Agricultural Faculty of Namik Kemal University in randomized split block design with three replications per treatment during 2004-2005 and 2005-2006. The objective of this study was to find out the contribution rates of awn, flag leaf, 1 st upper leaf blade, 2 nd upper leaf blade and other leaf blades to main yield components in three durum wheat cultivars (cv. Kiziltan-91, Kunduru-1149, and Yelken-2000). The results of this experiment showed that removal of awn, flag leaf, 1 st upper leaf blade, 2 nd upper leaf blade, and other leaf blades reduced significantly spike weight, number of grains per spike, grain weight per spike, and 1000-grain weight except the number of spikelets per spike. It was concluded that the organs play an important role in grain yield in durum wheat during grain filling stage.

The study was carried out with 3 bread wheat varieties (resistant KateA-1, sensitive Sultan 95, and middle resistant Golia) which are different response to drought. It was aimed to determine changes of some yield and quality characteristics in the wheat varieties with different seed size in the study. Artificial drought stress was created by chemical desiccant application (potassium chlorate with %4) after 14 days to heading of varieties, and productions of undersized seeds were achieved in 2009-2010 growing season. Undersized seeds and normal seeds were sifted through sieves of different sizes, and different seed and endosperm sizes (control are over 2.5 mm, 2.0 mm and under 2.0 m, desiccants are over 2.0 m and under 2.0 m) were generated. Regarding of the results it was shown that variety KateA-1 that is resistant to drought gave better results than the others in different endosperm and seed sizes. To gather with decreases in seed size was shown reduces in characters such as grain yield, plant height, spike length, protein content, wet gluten content of the varieties. Gluten indexes values increased by decreases in grain size. No important statistical effects of seed size on number of spikelets per spike, number of grain per spike, grain weight per spike, number of tillers per plant, number of fertile tillers per plant, harvest index, spike index, thousand kernel weights and test weight were found. Among the desiccant treated seeds, the highest grain yield mean was obtained from seeds over 2.0 mm sieve of the varieties. In addition, it was shown that they gave results as well as control seeds over 2.5 mm and 2.0 mm sieve for the characters. According to results of the study, it is said that there is no inconvenient in the use as seed of grain over 2.0 mm sieve.

This study aimed to evaluate the cold stress effect in natural field conditions by employing different rice sowing timings over three years, to identify national varieties tolerant to cold stress at the vegetative and generative stages, and to propose a data-derived solution regarding termination and resowing due to cold stress conditions. Early, regular, and late sowing dates were employed to capture natural cold stress conditions in a 3-year-long experiment. Sowing dates resulting in the greatest yields fluctuated from regular to late sowing dates, according to the stress duration in cold stress years. Yield losses resulting from cold stress ranged from 0.810 to 2.740 t ha-1 and reached 38.6%. ‘Halilbey,’ ‘Pasali,’ and ‘Mevlutbey’ were found to be most cold-tolerant varieties. Grain yield was correlated with plant number; the critical minimum level was between 60.8 and 79.6 plants m-2 and the optimum was 132.3 plants m-2 for economical yield. Cold stress negatively affected rice plant density, and plant densities below the critical minimum plant warranted crop termination and resowing, depending on application costs. Cold stress had a far more devastating effect on germination and seedling stages than on later development stages in temperate conditions.

Received: 14 February, 2000; accepted: 29 August, 2000 In this research, three bread wheat varieties were sown at six different plant densities in the experimental field of Tekirda đ Agricultural Faculty according to a split-plot randomised block design. A range of characters such as number of tillers per plant, number of spikes per plant, grain weight of tillers per plant, plant height, harvest index, plant yield and grain yield per hectare were investigated. The results of variance analysis showed that the effects of sowing rate and variety and their interaction on number of tillers per plant, plant height and grain yield per hectare were all significant. In addition, the effect of plant density on grain weight per tillers, grain yield per plant and number of spikes per plant was significant, whereas the effect of variety was only significant on harvest index. It was found that the number of fertile tillers per plant was the most suitable character as a selection criterion for improving grain yield in the Thrace Region. According to path analysis the direct and indirect effects of the measured characters on grain yield per plant and grain yield per hectare showed that the number of spikes per plant, harvest index, grain weight of tillers per plant and plant height had a direct positive effect on grain yield per plant. However, the number of spikes per plant and the number of tillers per plant had a negative effect on grain yield per hectare, while the harvest index and grain yield per plant had a positive direct effect.

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