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Homer A., Şahin M., Küçüközdemir Ü. (2016): Evaluation of pea (Pisum sativum L.) germplasm for winter hardiness in Central Anatolia, Turkey, using field and controlled environment. Czech J. Genet. Plant Breed., 52: 55-63.Winter pea can be grown in rotation with cereal crops in Central Anatolia, Turkey. However, winterkill can occur during harsh winters. The objective of this study was to screen pea accessions for winter survival, and identify genotypes with differential winter hardiness for future crop development. The plant material consisted of 58 accessions including local landraces, elite winter cultivars, selected lines and several checks. Twenty-five of them were evaluated under both field and laboratory conditions. The rest of the genotypes were tested under field conditions. Field trials were planted in Haymana, Ankara, and in Ulaş, Sivas, Turkey during the autumn of 2014. Winter hardiness was evaluated as the percentage of surviving plants. Differential survival of genotypes was observed at both locations. On average, the survival rate was lower in Ulaş (54.8%) than in Haymana (67.8%), and ranged between 1.5 and 100%. Turkish landraces TR 79404 (88.6%), TR 79407 (88.5%) and TR 80194 (84.8%) had survival percentages comparable with the three winter-hardy checks (Turkish cvs. Taşkent (90.0%) and Özkaynak (85.0%), US cv. Melrose (94.7%)). Twelve single plants were selected from these populations for future cultivar development. The European and US accessions, included in the trials for their previously reported winter hardiness, showed high levels of winter hardiness, and could be used in breeding programs. In the laboratory, no plants survived at -12°C and -16°C three weeks following the freezing test. Screening at -8°C generated differential survival among winter genotypes. Significant positive correlations (r = 0.67-0.87, P < 0.001) were found between the test environments for the percent survival.

The occurrence of herbicide‐resistant weeds has boosted interest in the use of crop allelopathy as a potential alternative to herbicides for weed control in rice (Oryza sativa). The phytotoxic compounds that are released by rice could help to enhance its competitive ability and improve weed management. This study aimed to screen rice genotypes for phytotoxic activity, quantify the amount of momilactone B in various rice tissues, and identify the potential parental lines for quantitative trait locus analysis. Therefore, a total of 41 cultivars from germplasm collections was evaluated for their effects. Significant differences were found among the rice cultivars in their ability to reduce the germination, root growth, and root dry weight accumulation of Alisma plantago‐aquatica. The leaf extract was the most inhibitory to germination. Out of the five cultivars that were tested, momilactone B was detected in four of them: Marateli, Kizilirmak, Karadeniz, and Kiziltan. Karadeniz and Kiziltan were identified as the rice cultivars with a high momilactone B content in the tissues and therefore they could be used in breeding programs to enhance the phytotoxic potential of rice. The development of a rice cultivar with proven allelopathic characteristics could provide an environmentally friendly and low‐cost approach for the control of A. plantago‐aquatica.

The effects of the plant growth regulator trinexapac-ethyl (TE), conjoined with different seeding rates of rice (Oryza sativa L.) milling yields, were evaluated in Turkey between 2009 and 2010. Two rice cultivars (Osmancık-97 and Karadeniz), three seeding rates (400, 500, and 600 seeds m-2), and four doses of TE (0, 100, 200, and 300 g ai ha-1) were compared. The experiments were designed in a randomized block in factorial ordering with 3 replicates. Quality factors including head, cargo, and total rice milling yields, 1000 grain weight, and lodging score were evaluated. Head rice milling yield was affected significantly; however, no statistically significant difference was seen with respect to cargo rice and total milled rice by TE dose. The effect was predicted to depend on grain weight and lodging, which decreased rice milling yield. Seeding rate did not have a significant impact on milling yields. There was a significant correlation between milling yields (head rice and total milled rice but not cargo rice) and both 1000-grain weight and lodging. A seeding rate of 500 seeds m-2 was the optimum value among all seeding rates, and the highest milling yields were obtained from Osmancık-97. Irrespective of genotype and seeding rate, treatments with 100, 200, and 300 g TE ai ha-1 increased head rice milling yield. All doses of TE reduced 1000 grain weight and lodging. Regression analysis revealed that increasing TE doses raised head rice milling yield.