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    ASSESMENT OF CORN (ZEA MAYS L.) GENOTYPES IN RELATION TO NITROGEN FERTILIZATION UNDER IRRIGATED CROPPING CONDITIONS IN TURKEY
    (Pakistan Botanical Soc, 2012) Ibrikci, Hayriye; Ulger, Ahmet Can; Buyuk, Gokhan; Korkmaz, Kursat; Ryan, John; Karnez, Ebru; Cakir, Bulent
    Efficient nitrogen (N) fertilizer management in crop production is based on supplying adequate amounts of the nutrient for optimum economic yield, while minimizing losses to the environment. Exploiting genotypic differences in N use is an additional consideration in achieving nutrient-use efficiency. Thus, in order to identify N-efficient corn genotypes, we established N-response field trials at 2 locations (University Research Farm, and Cutaem) for 2 years (1999, 2000) in the Cukurova region of Turkey. Ten corn genotypes, commonly grown in the region, were fertilized with N at application rates of 160, 240, 320 and 400kg N ha(-1). The optimum N fertilizer rate was probably in the 160-240kg N ha(-1) rate based on response data. There were no significant or consistent differences between genotypes and N application for grain yield and N uptake. The average agronomic efficiency ranged between 20 to 65% across the genotypes and decreased with increasing N application rates. The pattern was similar for other efficiency indices with decreases with applied N, but little or no genotype differences. It is apparent that the genotypes used were bred for N as well as yield. There was little evidence of differences between genotypes or their response to N. Thus, while genotypic selection of corn can be one of the suitable potential N management practices in the Mediterranean region where genetic diversity exists, it is not appropriate considering genotypes are homogenous with respect to N use.
  • [ N/A ]
    Öğe
    Assesment of Corn (Zea Mays L.) Genotypes in relation to nitrogen fertilization under irrigated cropping conditions in Turkey
    (2012) Ibrikci, Hayriye; Ulger, Ahmet Can; Buyuk, Gokhan; Korkmaz, Kursat; Ryan, John; Karnez, Ebru; Cakir, Bulent
    Efficient nitrogen (N) fertilizer management in crop production is based on supplying adequate amounts of the nutrient for optimum economic yield, while minimizing losses to the environment. Exploiting genotypic differences in N use is an additional consideration in achieving nutrient-use efficiency. Thus, in order to identify N-efficient corn genotypes, we established N-response field trials at 2 locations (University Research Farm, and Cutaem) for 2 years (1999, 2000) in the Cukurova region of Turkey. Ten corn genotypes, commonly grown in the region, were fertilized with N at application rates of 160, 240, 320 and 400kg N ha-1. The optimum N fertilizer rate was probably in the 160-240kg N ha-1 rate based on response data. There were no significant or consistent differences between genotypes and N application for grain yield and N uptake. The average agronomic efficiency ranged between 20 to 65% across the genotypes and decreased with increasing N application rates. The pattern was similar for other efficiency indices with decreases with applied N, but little or no genotype differences. It is apparent that the genotypes used were bred for N as well as yield. There was little evidence of differences between genotypes or their response to N. Thus, while genotypic selection of corn can be one of the suitable potential N management practices in the Mediterranean region where genetic diversity exists, it is not appropriate considering genotypes are homogenous with respect to N use.
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    Öğe
    Determination of critical period for weed control in the second crop corn under Mediterranean conditions
    (Academic Journals, 2009) Uremis, Ilhan; Uludag, Ahmet; Ulger, Ahmet Can; Cakir, Bulent
    Weeds are a major constraint in corn production. Understanding the critical period for weed control (CPWC) can be a tool for effective weed control and reducing the impacts of weeds. Three experiments were conducted to determine CPWC in the second corn crop from 1996 to 1998. The critical period for weed control in the second crop corn in the mediterranean region was determined to be from 131 to 927 growing degree days (GDD) after sowing in 1996, from 337 to 731 GDD in 1997 and from 266 to 551 GDD in 1998 for 10% yield loss; for 2.5 - 5% yield loss, the critical period starts with germination and lasts longer. Preemergence (PRE) or presowing (PPI) herbicides would be preferred to avoid higher yield losses. If a farmer can tolerate 10% yield loss, a postemergence (POST) herbicide can be applied in the second week after crop sowing, and the field should be kept weed free for 4 or 5 weeks. The duration of weed competition and time of weed removal also affect tasseling, silking, plant height, stem diameter, first ear's height and number of kernels in an ear, all of which correlate with corn yield.