Dried weight was recorded for the whole plant and each component.

1. Biomass Production, Nutrient Accumulation, and Tolerance to Heavy Metal of Selected Winter Canola Cultivars Canola field at flowering Statistical differences for distribution of magnesium (Mg) by cultivars, harvest and source: Cultivars* P = 0.0001 Harvest** P < 0.0001 Source** P < 0.0001 Statistical differences for distribution of zinc (Zn) by cultivars, harvest and source: Cultivars* P = 0.0295 Harvest** P < 0.0001 Source** P < 0.0001 Statistical differences for distribution of iron (Fe) by cultivars, harvest and source: Cultivars NS Harvest** P < 0.0001 Source** P < 0.0001 • ABSTRACT • Species of the Brassicaceae family may be excellent for uptake of heavy metals and nutrients. In this study, we evaluated the efficiency of eleven promising winter canola (Brassica napus) cultivars for their nutrient (Al, Ca, K, Mg, Mn, N, Na, S and P) uptake in the field and uptake of heavy metals (Se, Cd, Cu, Fe, Zn, and Cr) in the greenhouse. In the field study, three plants cultivar-1 replication-1 were randomly sampled at three different growth stages (rosette, anthesis and senescence) and partitioned into different parts, e.g., leaves, roots, stems, flowers, pods and seeds, to determine above-and below-ground biomass, and accumulation of nutrients. In the greenhouse study of heavy metals uptake, seedlings of all test cultivars were evaluated with four different heavy metals concentrations in the range found in Alabama soils and compared to an untreated control. Preliminary data indicate significant variations among the cultivars in roots (P< 0.0001) and stem (P = 0.0335) biomass production. The cultivar Titan produced significantly higher per plant biomass (11.3g of dry matter plant-1), while cultivar Kronos produced the least (5.5g of dry matter plant-1). Cultivars and harvest stages showed significant differences in nutrient uptake. The cultivar Kronos, which produced the least biomass, showed the highest accumulation of Al, Zn, Fe and Mn in its tissues. The differences between biomass production and nutrient uptake among the canola cultivars may identify their genetic potential for phytoremediation. • INTRODUCTION Canola (Brassica napus) • A cash crop that is known for its desirable oil quality and as feedstock for bio-diesel. • Canola is the second largest oil producing crop in the world providing up to 13% of the world’s oil supply (Raymer, 2002). • In North America, canola is grown throughout the Pacific Northwest, Upper-Midwest and Canada. • Scientists have identified canola as a possible candidate for phytoremediation to remediate soils contaminated with heavy metals. • Canola has a tap root system and profuse root hairs that allows the plant to be well-equipped for hyperaccumulation. • Pollution of soils by heavy metals is a problem that exists from activities involving the agricultural industries, mining industries, and chemical industries (Nascimento et al. 2005). • Since the early 1900s, heavy metal contamination of the biosphere has been increasing at a rapid rate causing major health problems to humans worldwide (Prasad et al., 2003). • SOILS OF NORTH ALABAMA • The Ultisols soils of North Alabama contain excessive level of Fe, Mn, Zn, Cr, Ni, Cu, Pb and Cd. Fe and Mn are the top pollutants accumulating with clay in the Bt horizons (Senwo and Tazisong, 2004). • This project investigated the variations among winter canola cultivars for production of biomass and response of seedlings to selected heavy metals in the range found in Alabama soils. • MATERIALS AND METHODS • Eleven genetically diverse canola cultivars were selected from the National Winter Canola Variety Trials grown at the Winfred-Thomas Agricultural Research Station, Alabama A&M University, in Meridianville, Alabama, and evaluated for biomass production and accumulation of nutrients. • Plot size consists of six rows with 18-cm row spacing, 1.3-meter wide and 6-meter long. • Samples (3 plants/cultivars/rep/harvest) were collected at three different growth stages: • Rosette (120 days after planting, DAP) • Flowering (150 DAP) • Senescence (250 DAP) • Each sample was partitioned into different components: • Leaves and roots (Rosette – 1st harvest) • Leaves, roots, stems and flowers (Spring – 2nd harvest) • Roots, stems, pods and seeds (Senescence – 3rd harvest) Celeste P. Bell*, Ernst Cebert, Rufina Ward and Zachary Senwo Department of Plant and Soil Science, Alabama A&M University Normal, AL 35762 Canola during vegetative growth Canola plots at senescence • Dried weight was recorded for the whole plant and each component. • The plant parts were grounded then digested with a Microwave Digester, using 10 ml of 70% Nitric Acid and analyzed. • Inductively Coupled Plasma (ICP) was used to determine the content of heavy metals and minerals nutrients. • SAS (Statistical Analysis System, ver 9.1, PROC GLM and Tukey’’s mean separation analysis) was used to determine differences among: • Cultivars • Harvest • Source • SAS Graph-N-Go and ODS Graphics were used for graphical output. • Experiment II (Greenhouse) • In this study three canola cultivars: Abilene, Jetton and Titan were grown in the greenhouse to observed and evaluated the impact of heavy metals of seedling growth. • ►Five heavy metals were • used: Cd, Cr, Cu, Mn • and Zn plus a control • ►Samples were collected • after 4 weeks of growth. Resultsfor canola cultivars’ biomass production (grams/plant), uptake of selected nutrients (mg/kg dry weight), and the impact of heavy metals on seedlings: root biomass, leaf damage and leaf area development are shown on figures 1a – 3c. Distribution chart showing total biomass produced by each cultivar and its source. Statistical differences were: Cultivars** P < 0.0001 Harvest** P < 0.0001 Source** P < 0.0001 Statistical differences for distribution of manganese (Mn) by cultivars, harvest and source: Cultivars NS Harvest* P < 0.0001 Source* NS Statistical differences for distribution of copper (Cu) by cultivars, harvest and source: Cultivars NS Harvest** P < 0.0001 Source** P < 0.0001 1a 1b 1c 2b 2a 2c Table 1. Range of heavy metals (in ppm, Alabama soils) used in this study to evaluate the impact on seedling growth of three canola cultivars. Heavy metals Level 1 Level 2 Level 3 Level 4 Figures 1a, - 2c show the biomass and nutrient accumulation for canola cultivars selected for their superior performance in northern Alabama . Cd 0.20 1.0 2.0 3.0 Statistical differences for distribution of rootbiomass by cultivars, metals and levels: Cultivars** P < 0.0001 Metals* P = 0.0386 Levels NS Statistical differences for distribution of leaf damage by cultivars, metals and levels: Cultivars NS Metals** P < 0.0001 Levels** P < 0.0001 Statistical differences for distribution of leaf area by cultivars, metals and levels: Cultivars NS Metals** P < 0.0001 Levels NS Cr 13.4 50.0 75.0 150 Cu 3.2 27.0 54.0 82.0 3a 3b 3c Mn 30.3 1,550 3,100 4,645 Zn 22.6 113.0 227.0 340.0 Figures 3a, b and c show the response of seedlings from three winter canola cultivars treated with selected heavy metals at four different levels of concentration. CONCLUSION Significant statistical differences among cultivars for biomass production and among nutrients tested, indicate that such genetic differences will allow the selection of canola cultivars for their higher capacity to accumulate such elements as: Zn and Fe. However, highly significant difference exists for time of harvest and plant source (roots, leaves, stems, flowers, pods and seeds) where nutrients accumulate. The impact of heavy metals on canola seedling development was adversely affected by manganese; leaf damage to all cultivars gradually increased from no damage at level 1 to severe (leaf death) at level 4 (Figure 3b). Among the three cultivars evaluated in the heavy metal study, seedlings of Titan was least affected by increasing levels of heavy metals, except for root biomass where cultivar Jetton was significantly better. These results represent preliminaryanalysis of field and greenhouse studies. The data show that winter canola cultivars can be selected for conditions in the southern region of the United States and as a candidate for phytoremediation. REFERENCES Nascimento, Clistenes, D. Amarasiriwardena, B. Xing. 2005. Comparison of natural organic acids and synthetic chelates at enhancing phytoextraction of metals from a multi-metal contaminated soil. Environmental Pollution. 1-10. Prasad, Vara Narasimha Majeti, H. Freitas. 2003. Metal hyperaccumulation in plants – Biodiversity prospecting for phytoremediation technology. J. Biotechnology. 6:285-321. Raymer, P.L. 2002. Canola: An emerging oilseed crop. p. 122–126. In: J. Janick and A. Whipkey (eds.), Trends in new crops and new uses. ASHS Press, Alexandria, VA. Senwo, Z. N., I. A. Tazisong. 2004. Metal content in soils of Alabama. Comm. Soil Sci. and Plant Analysis. 35: 2837-2848. • ACKNOWLEDGMENT • The Kansas State University National Winter Canola Variety Trial (NWCVT). Anson Josephand Geoffrey Reid for their help in field and laboratory work.