التوريث و التحصيل الوراثي لمعايير انتخاب لتحسين أداء الذرة الصفراء تحت قلة و وفرة النتروجين

الملخص EN

Four selection criteria ; grain / plant (GN), anthesis-silking interval (ASI), yield efficiency (YE) and leaf area duration (LAD) were, tested in selected plants of maize (Zea mays L.) cv.R-106.

The experiment was applied for four consecutive seasons (2009-2010) at the farm of the Dept.

of Field Crops / College of Agric.

/ Univ.

of Baghdad.

Plants of high grain coincided with the desired criterion were taken, selfed, with s1progeny approach by 10 % selection intensity and harvested for three selection cycles under 200 and 400 kg N / ha.

Seeds of third cycle of each selection criterion were planted for panmixia.

Heritability narrow sense measured by parent-off spring regression, genetic gain due selection for tow selection cycles (spring 2009-spring 2010).

Results showed selection effects via selection criteria under nitrogen stress.

Leaves area duration increased 10.4, 2.2 and 7.3 days for three cycles respectively.

Phenotypic variation decreased by 41 % from C1 to C3.

Anthesis-silking interval decreased 1.4, 0.3 and 1.6 days for three cycles respectively.

Phenotypic variation decreased by 43 % from C1 to C3.

Grain number.plant-1 increased 123.7, 193.2 and 84.3 grain.plant-1 for three cycles respectively.

Phenotypic variation decreased 59.2 %.

Yield efficiency increased 79.8, 63.4 and 121 gm.m-2.

Phenotypic variation decreased by 75.5 % from C1 to C3.

Selection cycles also affected the growth criteria of all selection plants under high level of nitrogen in the same way.

LAD increased 7.4, 0.5 and 4.6days for three cycles respectively.

Phenotypic variation decreased by 37.9 % from C1toC3 under high nitrogen.

ASI decreased 1.6, 1 and 0.4 days for three cycles respectively.

GN.plant-1 increased 107.3, 129.7 and 88.5 for three cycles respectively.

Phenotypic variation decreased 71 %.YE increased 67.8, 45.3 and 52.3 gm.m-2.

Phenotypic variation decreased by 62.2 % from C1 to C3 under high nitrogen.

Heritability (h2 n.s %) for GN, ASI, YE and LAD after tow cycles of selection under 400 kg N / ha were 41.6, 56.3, 38.6 and 57 respectively, these values were higher than those under 200 kg / ha were 15, 28.5, 9, and 44 GS for the four mention selection criterion gave higher values under high nitrogen than low nitrogen (61.9, 0.7, 5.9 and 21.2) under high nitrogen, (18.2, 0.4, 4.7 and 4.9) under low nitrogen Counting of these results it was conclude that using any of these four selection criterion will be effective to improve grain yield of open-pollinated cultivar of maize.

We recommend to use these criteria for selection and to devise lines that will tolerant toward low nitrogen.