Fertilizer effects on yield, mineral and amino acid composition, dietary fibre content and nutritive value of leeks.
In pot experiments with greatly differing rates of N, P, S, K and Ca, dry matter (DM) yields of leek stems varied from 25 to 164 g/pot. Total-N and NO3-N concentrations varied from 1.18 to 3.56% and from 10 to 1515 ppm in DM, respectively. Both N applications and P and K deficiency greatly increased total-N and NO3-N content. S applications increased total-S content from 0.047 to 0.359% in DM, of which between approximately 100 to 25% were found in methionine+cystine. Total-N/total-S ratios decreased from 57 to 6 with the highest S level. P and K applications increased their respective content in DM two- and threefold. Severe Ca deficiency reduced Ca content from 0.495 to 0.045%. Iron, zinc, manganese and copper contents varied from 33-69, 14-26, 11-34 and 3.1-5.7 ppm in DM, respectively. Increasing N contents, whether due to N applications or P or K deficiency, decreased the content of all essential and some other amino acids in crude protein. Both S and severe P deficiency had a pronounced negative effect on amino acid composition and chemical score. Only glutamic acid (glutamine) and arginine were increased by increasing N contents. However, expressed as g/kg DM the concentrations of all amino acids were positively correlated with protein content. S and P deficiency reduced total dietary fibre (TDF) content of DM from 28.3 to 18.6% and 17.4%, respectively, of which between 53 and 60% were insoluble dietary fibre (IDF). Digestible energy (DE) was positively correlated with protein content (r = 0.90**). In N-balance trials with rats, increasing protein concentrations (50% of total protein given as casein and supplemented with 1% methionine) raised the true digestibility (TD) of the protein from 44 to 72%. The biological value (BV) of protein was generally high, with a mean of 91.7. N deficiency tended to increase and S deficiency tended to decrease the BV.
Eppendorfer
W H
WH
Department of Agricultural Sciences, Royal Veterinary and Agricultural University, Frederiksberg, Denmark.
Eggum
B O
BO
D000596:Amino Acids / Q000032:analysis*; D000818:Animals; D002118:Calcium / Q000032:analysis; D004043:Dietary Fiber / Q000032:analysis*; D005308:Fertilizers / Q000009:adverse effects*; D008274:Magnesium / Q000032:analysis; D008345:Manganese / Q000032:analysis; D008903:Minerals / Q000032:analysis*; D009566:Nitrates / Q000032:analysis; D009584:Nitrogen / Q000032:analysis; D009753:Nutritive Value; D051381:Rats; D012964:Sodium / Q000032:analysis; D013455:Sulfur / Q000032:analysis; D014675:Vegetables / Q000737:chemistry*
D000596:Amino Acids; D004043:Dietary Fiber; D005308:Fertilizers; D008903:Minerals; D009566:Nitrates; D008345:Manganese; D013455:Sulfur; D012964:Sodium; D008274:Magnesium; D009584:Nitrogen; D002118:Calcium