Received: 27 February, 2009. Accepted: 29 May, 2009. Original Research Paper International Journal of Plant Developmental Biology ©2009 Global Science Books Physio-morphological Response of Erucic acid-Free Genotypes of Rapeseed-mustard to the Application of Graded Combinations of Nitrogen, Phosphorus and Sulphur Manzer Hussain Siddiqui * • Firoz Mohammad • Mohd. Nasir Khan • Mohd. Masroor A. Khan Plant Physiology Section, Department of Botany, Aligarh Muslim University, Aligarh-202 002, India Corresponding author: * manzerhs@yahoo.co.in ABSTRACT A field experiment was conducted to study the effect of five graded combinations of nitrogen (N), phosphorus (P) and sulphur (S) on growth characters, physio-biochemical parameters and yield characteristics as well as fatty acid composition of the oil of three genotypes of rapeseed-mustard (two erucic acid-free, viz. Brassica napus L. cv. ‘Hyola PAC-401’ and Brassica juncea L. Czern. & Coss. cv. ‘TERI (0E) M21-Swarna’, and one the best performing high-yielding, B. juncea cv. ‘Rohini’ as a check). The nutrient combinations with a uniform dose of 30 kg K ha -1 included (i) 0 kg N + 0 kg P + 0 kg S ha -1 (N 0 P 0 S 0 ), (ii) N 30 P 10 S 17 , (iii) N 60 P 20 S 34, (iv) N 90 P 30 S 51 and (v) N 120 P 40 S 69 . Application of N 90 P 30 S 51 proved best for most parameters studied. ‘Hyola PAC-401’ surpassed other cultivars in seed and oil yield. The interaction N 90 P 30 S 51 x ‘Hyola PAC-401’ (also N 90 P 30 S 51 x ‘TERI (0E) M21-Swarna’) proved superior for most parameters, including seed yield, oil yield and erucic acid content. _____________________________________________________________________________________________________________ Keywords: fatty acid composition of oil, NPS application, oil yield, seed yield INTRODUCTION Rapeseed-mustard is the third most important oilseed crop of the world, after soybean and palm (Batra 2000). How- ever, cultivars of this group contain 40-50% erucic acid in their oil (<2% is desired) responsible for cardiac diseases (Pachauri 2001). Keeping this in view, oilseed researchers have been able to develop and introduce several improved quality cultivars including those free from erucic acid. The yield potential of Brassicas, as for others crops, can be realized by proper management of nitrogen (N), phospho- rus (P) and sulphur (S) fertilizer. N nutrition has strong regulatory influence on S assimilation and vice versa (Duke and Reisenauer 1986; Hawkesford et al. 1995). It is well known that when a full dose of N applied basally as a single application, most of it is rendered unavailable to plants due to many factors. For example, up to 50% of the applied N may be lost through leaching, decomposition, volatilization, and conversion to an unavailable form (Dejoux et al. 2003). Therefore, it is necessary to understand the plant processes and storage method for N and other nutrients. Once new crop plants are released, it becomes imperative to workout the precise package of farm practices so as to exploit their genetic potential fully. Of these, mineral nutrient manage- ment plays an important role in enhancing the productivity of crops. Therefore, in the present study an effort was made to evolve management technology of N along with S and P application for optimal seed as well as oil yield in rapeseed- mustard (two erucic acid-free genotypes were tested and one best-performing, high-yielding genotype as a check). MATERIALS AND METHODS A field experiment was conducted according to a factorial ran- domized block design at the Farm/Botanical Garden of the Aligarh Muslim University, Aligarh (27° 52 N latitude, 78° 51 E longi- tude and 187.45 m asl), India. The soil of the experimental field was a sandy loam with a pH (1: 2; soil: water) -8.00, E.C. (1: 2; soil: water) -0.65 dS m -1 ; available minerals: N (181 kg N ha -1 ), P (22 kg P ha -1 ), and K (308 kg K ha -1 ). Five graded combinations of soil-applied N, P and S were applied to three cultivars of rapeseed- mustard (two erucic acid-free genotypes, viz. Brassica napus L. cv. ‘Hyola PAC-401’ and Brassica juncea L. Czern. & Coss. cv. ‘TERI (0E) M21-Swarna’, and one best-performing, high-yielding B. juncea cv. ‘Ronini’ as a check) grown in 10 m 2 plots. The nutri- ent combinations with a uniform 30 kg K ha -1 included (i) 0 kg N + 0 kg P + 0 kg S ha -1 (N 0 P 0 S 0 ), i.e. control, (ii) N 30 P 10 S 17 , (iii) N 60 P 20 S 34 , (iv) N 90 P 30 S 51 and (v) N 120 P 40 S 69 . The source of N was urea and of P and S, single superphosphate. The half dose of N and full of P, K and S was applied at the time of sowing and the remaining half dose of N was top-dressed after 30 days after sowing (DAS). The experimental field was irrigated at 30, 60 and 90 DAS, and weeding was undertaken twice at 30 and 60 DAS. There were three replicates for each treatment. The performance of the crop was assessed in terms of growth characteristics (shoot length plant -1 , leaf number plant -1 , area leaf -1 , leaf area index (LAI), fresh weight plant -1 and dry weight plant -1 ) and physio-bio- chemical parameters (net assimilation rate, leaf carbonic anhyd- rase activity and leaf NPK content) at 45 and 60 DAS and yield characters (pods plant -1 , seeds pod -1 , 1000-seed weight, seed yield ha -1 , oil content and oil yield ha -1 ) and fatty acid composition of the oil at harvest. Leaf area was measured by the gravimetric method and LAI, according to Watson (1958). Net assimilation rate was calculated using the formula of Milthorpe and Moorby (1979). Carbonic anhydrase activity was measured by the titration method of Dwivedi and Randhawa (1974). Leaf N and P contents were determined according to the method of Lindner (1944) and Fiske and Subba Row (1925), respectively. Leaf K content was estimated by flame photometry (Fotoflame, AIMIL Ltd. New Delhi, India). Oil of the seeds was extracted by taking 25 g meal of ground seeds and transferring into a Soxhlet apparatus to which 100 mL pure petroleum ether was added. The apparatus was kept on a water bath at 60°C for ~6 h. At the end of each extraction process, the petroleum extract of seeds was left in air to evaporate the petroleum ether. The oil left after the evaporation of petroleum ether was weighed and expressed as percentage of the mass of the ®