اسم المؤلف:
سندس عبد الكريم محمد العبد الله
اسم المشرف:
عبد المهدي صالح حسين الانصاري
وليد عبد الرضا السباهي
المستخلص:
A field experiment was conducted at Al - Daire site 40 km north of center Basrah Governorate .The study was conducted to investigate the effects of different nitrogen fertilizer levels on dry matter accumulation, (N, P, K) uptake, distribution in different parts of three cultivars of wheat plants and their yield during two seasons (2011 - 2012 & 2012 - 2013).The experiment was split - plots in R.C.B.D design with three replicates, Nitrogen rates (0, 60,120 and 240Kg ha - 1 occupied the main plots, while (IPA - 99, Abu - Graib and Latifia) Cultivars Occupied the sub - plots. Samples of wheat plants were collected at 10 growth stages : seedling stage, tillering (main shoot and 1 tiller), tillering (main shoot and 4 tillers), stem elongation, booting, 50% of spike emergence, 50% flowering, milk stage, dough stage and maturity. Each plant sample was separated into different plant parts : blades, sheathes, stems, flag leaves, spikes and seeds. These parts were dried at 70°C and dry weight of each part was recorded and sub sampled for chemical analysis of N , P , and K. Growth parameters (No. of day till 50% flowering , No. of day from 50% flowering to Maturity , flag leaf area , plant height, spike length and No of tillers m - 2) , yield components (No. of spike m - 2, No. of grain in spike and weight of 1000 grain ),grain yield, biological yield, harvest Index, grain protein percentage and nitrogen use efficiency were also studied.Results showed that dry matter accumulation in plants of all cultivars did not differ at early growth period, While after the growth stage of 50% flowering plants dry weight of Cv.IPA - 99 was higher than other cultivars, This difference in dry weight continue till maturity stage at which total dry weight were 14473.58, 13373.96 and 12743.59 Kg ha - 1 for IPA - 99, Abu - Graib - 3 and Latifia respectively.Dry matter yield were not affected by N levels during the early growth period ,then after dry weight of plants increased as N rates increased ,total dry weight were10752.61, 12737.49 and 15347.10 Kg ha - 1for 0, 60 , 120 Kg Nha - 1 respectively, with no differences between 120 and 240 Kg Nha - 1 levels.Dry matter of plant parts differed among cultivars, with IPA - 99 having the highest results. Increasing nitrogen rates increased weight of different plant parts, but did not influence the relative proportion of each plant part for all cultivars.IIResults also showed reduces in dry weight of different plant parts(except grains)after reaching a maximum weigh at dough stage for Spikes, and 50% flowering for the other parts. The highest decreased was in blades and lowest in sheathes. The application of N fertilizer decreased translocation of dry matter from plant parts to grains. Data showed that no differences in nutrient uptake were observed for cultivars till ending of tillering stage, but after this stage IPA - 99 cultivar showed highest uptake till the end of the season. Nitrogen uptake was157.68,136.72,124.51 Kgha - 1 ,P uptake 19.70,16.93,15,67 Kg ha - 1, K uptake136.30,121.10,112,60 Kg ha - 1 for IPA - 99,Abu - Graib - 3 and Latifia, respectively.Increasing N rate increased nutrient uptake of different plant parts, but did not influence the relative proportion of each plant part for all cultivars.uptake of N, P, and K for all cultivars and nitrogen rates declined as the season progressed, this decline differed among nutrients and plant parts.Grain contained 59.20, 79.00 and 7.45% of total nutrient N, P and K uptake, whereas vegetative parts contained 40.80, 21.00 and 92.55% of total nutrient uptake, respectively.Cultivar IPA - 99 resulted in highest grain yield among studied cultivars. Increasing N rate from 0 to 120 Kg N ha - 1 only increased grain yield, the rate 240 KgNha - 1 did not affect yield significantly as compared with that of 120 Kg N ha - 1.Results also showed a significant interaction between Cultivars and N rates. The highest grain yield obtained at treatment IPA - 99×240 Kg N ha - 1with no significant differences than IPA - 99×120 KgNha - 1.Results indicated that highest nitrogen use efficiency (66.23%) was found in plant of IPA - 99 cultivar, whereas, the lowest efficiency (47.37%) was found in plant of Abu - Graib - 3 cultivar. At all cultivars increasing N rates to 240 KgNha - 1 decreased nitrogen use efficiency.Therefore it can be concluded that 120 Kg Nha - 1 can be recommended as the best rate for N to all cultivars under similar growing conditions
