Growth and yield of wheat are affected by environmental conditions and can be regulated by sowing time and seeding rate. In this study, three sowing times [winter sowing (first week of September), freezing sowing (last week of October) and spring sowing (last week of April)] at seven seeding rates (325, 375, 425, 475, 525, 575 and 625 seeds m )2 ) were investigated during the 2002-03 and 2003-04 seasons, in Erzurum (Turkey) dryland conditions, using Kirik facultative wheat. A split-plot design was used, with sowing times as main plots and seeding rates randomized as subplots. There was a significant year · sowing time interaction for grain yield and kernels per spike. Winter-sown wheat produced a significantly higher leaf area index, leaf area duration, spikes per square metre, kernel weight and grain yield than freezing-and spring-sown wheat. The optimum time of sowing was winter for the facultative cv. Kirik. Grain yields at freezing and spring sowing were low, which was largely the result of hastened crop development and high temperatures during and after anthesis. Increasing seeding rate up to 525 seeds m )2 increased the spikes per square metre at harvest, resulting in increased grain yield. Seeding rate, however, was not as important as sowing time in maximizing grain yield. Changes in spikes per square metre were the major contributors to the grain-yield differences observed among sowing times and seeding rates. Yield increases from higher seeding rates were greater at freezing and spring sowing. We recommended that a seeding rate of 525 seeds m )2 be chosen for winter sowing, and 575 seeds m )2 for freezing and spring sowing.

SummaryThe yield response of a wheat (Kirik) and a barley (Tokak 157/37) cultivar to inoculation with Azospirillum brasilense Sp246 and Bacillus sp. OSU-142 was studied in relation to three levels of N fertilization (0, 40, and 80 kg ha ±1 ) under field conditions in Erzurum, Turkey, in 1999 and 2000. Seed inoculation with A. brasilense Sp246 significantly affected yield and yield components, both in wheat and barley. On average of years and N doses, inoculation with A. brasilense Sp246 increased spike number per m 2 , grain number per spike, grain yield, and crude protein content by 7.2, 5.9, 14.7, and 4.1 % in wheat and by 6.6, 8.1, 17.5, and 5.1 % in barley, respectively, as compared to control. Inoculation with Bacillus sp. OSU-142 significantly increased kernel number per spike in wheat, but no significant effect was determined in the other characteristics. Grain yields and yield components were also higher at all levels of nitrogen fertilizer in the inoculated plots as compared to the control. However, these increases diminished at high fertilizer levels. These results suggest that application of the growth promoting bacteria A. brasilense Sp246 may have the potential to be used as a biofertilizer for spring wheat and barley cultivation in organic and low-N input agriculture.

RESUMO-O trabalho foi realizado com o objetivo de avaliar as características produtivas de forrageiras anuais de inverno (Avena strigosa Schereb, Lolium multiflorum Lam, Avena sativa, Triticum aestivum, Secale cereale e Triticosecale Wittmack) em quatro épocas de semeadura (11/3; 08/4; 06/5 e 03/6 de 2009). Foram avaliados o número de dias para o primeiro corte, o número de cortes, dias de utilização da pastagem, a densidade de plantas e perfilhos, a produção total, a matéria seca residual e a produção por corte. Houve interação significativa entre forrageiras e épocas de semeadura para todas as variáveis analisadas, o que possibilita alterar o planejamento forrageiro combinando cada forrageira dentro da melhor época de semeadura, direcionando a produção de forragem com o objetivo de suprir os vazios forrageiros. Uma das opções é a semeadura de aveia preta no início de março suprindo mais convenientemente as forragens no outono aos animais, em relação à sua semeadura em abril, mesmo que esta apresentasse uma produção total de forragem maior. Porém, se a maior necessidade de forragem é na primavera, a melhor combinação seria azevém semeado em junho. As aveias brancas, os azevéns, e a aveia preta IAPAR 61, são materiais com alta capacidade de produção e distribuição de forragem, especialmente se semeadas até início de maio. Palavras-chave: Aveia. Plantas forrageiras. Semeadura. ABSTRACT-This study was carried out in order to evaluate the productive characteristics of annual winter forages (Avena strigosa Schereb, Lolium multiflorum Lam, Avena sativa, Triticum aestivum, Secale cereale and Triticosecale Wittmack), on four sowing dates (11 March, 8 April, 6 May and 3 June 2009). The work evaluated the number of days to first harvest, the number of harvests, days of pasture usage, plant and tiller density, total production, residual dry matter and production per harvest. There was significant interaction between forages and sowing dates for all the variables analysed, which makes possible altering forage planning, combining each forage type with its best sowing date and directing forage production in order to fill any gaps. One option is the sowing of oats at the beginning of March, more conveniently supplying fodder to animals in the autumn relative to its being sown in April, even though this represents greater total forage production. However, if the greatest need for forage is in the spring, the best combination would be ryegrass sown in June. White oats, ryegrass, and oats IAPAR 61, are materials which have a high capacity for fodder production and distribution, especially when sown by the beginning of May.

IntroductionDrought is a serious stress factor restricting agricultural production in many parts of the world, including Turkey. Plants can be exposed to drought from seeding to harvesting (Gunes et al., 2006). There are 2 main effects of drought on crop production: the prevention of seedling emergence and a decrease in development and yield. In the early stages of development, particularly in insufficient water conditions, it is important for plants to effectively use available soil moisture (Clarke et al., 1984;Acevedo, 1987;Richards, 1992). Drought in the early development stages causes earlier flowering and decreases in plant height, leaf area, and the number of fertile tillers (Day and Intalap, 1970;Robertson and Giunta, 1994). Even if sufficient soil moisture is supplied in the postflowering stage, drought prior to flowering lowers the grain-filling period and grain weight (Öztürk and Çağlar, 1999).Due to irregular and insufficient rainfall, drought can be experienced during the sowing period, emergence, and seedling development periods in dry farming areas of different geographical regions of the world (Adjei and Kirkham, 1980;El Hafid et al., 1998), including Turkey. It is important to have good and early seedling establishment for high yield and stable wheat production in dry farming conditions. Insufficient available water in the early development stages significantly constrains grain yield through decreasing germination, emergence, seedling development, and establishment (Blum et al., 1980;Naylor and Gurmu, 1990;Richards and Lukacs, 2002).For stable crop production, it is important to minimize yield loss due to stress factors. This can be done by selection or breeding plants resistant to stress factors. Several selection criteria were set to determine the best parents to use in breeding programs and to classify populations based on tolerance to drought in the early development stages (Gavuzzi et al., 1997;Dhanda et al., 2004). Coleoptile length (Rebetzke et al., 1999), seedling survival after drought (Winter et al., 1988), and seedling vigor (Rebetzke et al., 2004;Reynolds et al., 2006) measurements have been successfully used for selection of drought tolerant wheat genotypes in respected breeding programs.

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