Effect of irrigation treatments upon the chemical constituents ofHibiscus sabdariffa L.

Summary The effects of Se and P on the dry matter yield and chemical composition of Raya (Brassica juncea Cos. var. R.L. 18) were studied in the green-house. The dry matter yield in P treated and untreated pots increased with Se application upto 2.5 ppm. With further increase in Se dose upto 10 ppm, dry matter yield decreased. The increase in P dose from 0 to 50 ppm increased dry matter yield in all Se treated and untreated pots but 100 ppm P rather showed decrease in dry matter yield as compared to 50 ppm P.The Se concentration increased by about 100 fold with the application of 10 ppm Se over 0 ppm Se where P was not added whereas increase was 258 and 336 times when 50 ppm and 100 ppm P was added, respectively. Inorganic, organic and total P increased with increasing Se and P. The increase in inorganic P was more than organic and total P. S and N concentration decreased with increasing Se application and increased with P application.Crude protein showed the same behaviour as N. The total sulphur-containing amino acids (which ranged from 39 to 49% of crude protein) and individual sulphur-containing amino acids like methionine (16.9 tot 20%) cysteine (9.8 to 13%) and cystine (12.3 to 15.9%) decreased with the increasing selenium but increased with increasing phosphorus. N/S ratio in the plant showed significant negative correlation with total sulphur-containing amino acids (r=–0.940^**), methionine (r=–0.951^**), cysteine (r=–0.929^**) and cystine (r=–0.920^*) whereas total sulphur in the plant showed positive significant correlation with methionine (r=0.805^**), cysteine (r=0.924^**) and cystine (r=0.821^**).