1. Root biomass and grain yield of Pavon 76 wheat and its Near isogenic Lines in Organic and Synthetic Fertilizer Systems Ruth Kaggwa-Asiimwe 1, Mario Gutierrez-Rodriguez 1, Giles Waines 2, and Guangyao Wang 1 1 School of Plant Sciences, University of Arizona, Maricopa Ag Center, 37860 W. Smith-Enke Rd, Maricopa, AZ 85138 2 Department of Botany and Plant Sciences, University of California, Riverside, CA 92521-0124  The plant root system has been earmarked as the key to the next green-revolution, especially regarding efficiency of nutrient uptake (Gerwin, 2010).  In an effort to improve spring wheat cultivars, breeding efforts have involved wheat-rye translocations, particularly using the short arm of the rye chromosome 1R (1RS).  The 1RS translocations to the wheat chromosome arms 1AL and 1BL have been the most extensively used because, in addition to the resistance loci, they positively affect agronomic traits (Lukaszewski, 1990).  Previous studies evaluated the Pavon76 1RS translocations in drought and well-watered conditions and documented agronomic superiority of the isogenic lines (Ehdaie et al., 2003).  However information on their root, shoot growth and yield performance in organic vs synthetic fertilizer conditions would enhance breeding efforts.  The spring bread wheat variety Pavon76 and three of its near isogenic lines 1RS.1AL, 1RS.1BL and 1RS.1DL were evaluated in a field experiment at the University of Arizona’s Maricopa Ag Center from 2009 to 2010.  The genotypes’ growth performance was compared in synthetic nitrogen (N) and organic fertilizer systems, each consisting of a high and low rate. The nitrogen rates for the organic fertilizer were 180 and 300 Ibs N/Acre (Org 1&2) and those for Urea were 120 and 200 Ibs N/Acre (Con 1 and 2), respectively.  Root and shoot measurements were made at the flag leaf, anthesis and physiological maturity growth stages for one isogenic line 1RS.1AL and the parent line Pavon76.  Grain yield attributes for all four genotypes were evaluated at harvest.  The genotype 1RS.1AL had higher root and shoot biomass than the parent line Pavon76 at all 3 stages but this was only significant at physiological maturity.  Root mass increased with rate of organic fertiliser but decreased with increased synthetic fertiliser.  1RS.1BL had significantly higher shoot biomass and grain yield at physiological maturity of all four genotypes evaluated, regardless of the nature and rate of fertilizer applications.  At harvest the grain yield performance trend for four genotypes was 1RS.IBL > 1RS.1DL >1RS.1AL > Pavon76.  Plants under the high rate synthetic fertilizer treatment (Con2) out performed the lower rate (Con1) and the two organic treatments (Org1 and 2), in terms of grain yield, thus [Con 2> Con 1>Org2> Org1 ]. Materials and Methods Results References. 1. Gewin V.. 2010. In Nature News Feature. 466, 552-553 (2010).doi:10.1038/466552a. 2. B. Ehdaie, R. W. Whitkus, and J. G. Waines. 2003. In Crop Sci. 43:710–717). 3. Dimitri.C.and Greene,C.., 2002. www.ers.usda.gov/publications aib777/www.ers.usda.gov/publications aib777/ 4. Lukaszewski.A.J.1990. In Crop science, vol. 30, n o 5, pp. 1151-1153.  Results showed a stronger root mass and grain yield response to increased rate of organic fertiliser than the synthetic form.  Results also indicate that the near isogenic lines perform better than their parent line and thus could be used to improve wheat growth and yield. Fig:- 2. Grain yield by genotype and by fertilizer system  To evaluate growth and yield performance of three near isogenic lines 1RS.1AL, 1RS.1BL, 1RS.1DL of Pavon76 and their parent line, in organic and conventional fertilizer systems. Objectives Conclusion Fig1 : Root mass by genotype and by fertilizer system at different wheat growth stages 1.To compare and correlate nutrient use efficiency & nitrate leaching losses with root mass among the genotypes. 2.To examine and compare the genotypes root structure, and lengths of component root types. 3.To assess root growth vigor early in the season for all the genotypes Wheat plants after root washing Introduction Future Experiments

2. Grain yield graphs are presented separately for variety and fertiliser system. Because there was no significant interaction between the above two factors; ie fertilizer effect did not depend on variety. Challenges with organic systems:-Nitrogen mgt in organic farming systems is complex. The supply of N from organic sources is difficult to synchronise with crop demand (Pang and Letey,2000). In organic farming, the limited amounts of available N require more effective distribution among the various crops to optimise farm results.(Arnout van Delden,2001). Another difficulty with organic grain production is meeting the high nitrogen requirements for cereal grain crops with organic fertilizer sources, which are typically higher in phosphorus and potassium; recommends to Apply manure and organic fertilizers after the establishment of the crop, to minimize nitrogen losses, and enhance the availability of nutrients during the grain fill period (annearundel.umd.edu/.../Organic%20 No-Till%20Grains)%20Preliminary.pdf

3. Shoot biomass (g/1m) TilleringjointingHarvest Pavon7620.81a76.32a310.4 1RS.1AL18.56a70.89a265.15 Table 2:- Yield parameters at harvest per 1m Variety No of Spikes Grain yield(g)HI % Straw yield(g) PAVON 7679.4a120.4ab37.4ab310.4a 1RS.1AL64.7a90.3b33.9b265.1a 1RS.1BL81.8a129.2a39.3a326.4a 1RS.1DL78.6a110.0ab37.8ab291.8a.