NUTRITIONAL RETRANSLOCATION EFFICIENCIES IN SOME AGROFORESTRY SPECIES OF SRI LANKA

Abstract

Studies on nutrient resorption efficiency or 13 major agroforcstry spccles (Gltricli/wIcpiu Ill. Alstonia SCIIOI(/ris. MU((/r({/lgu peltuta, Artocarpus intcgrijoli«, ArI(}(,{lJpIIS altili»,Milngllel'{{ indica, Tcrniinalia c({{I(//NI, Acacia auricu litorm is, Acacia tnanguu«. l'sidimnglliljil\,({, Ncpheliutn /(IPP({CCIIIll, M(//lilk({lYI sapota and Trctua orientalis; ill Sri Lanka wereconducted at the Faculty or Agriculture, Mapalana. Kamburupiuyu during 1<)<)7NX. Here.three trees from each species, and 3 branches from each tree were randomly selected andmature and senescent leaves were collected from each branch and analyscd tor per centnitroucn, phosphorous and potassium,

Considerable variations in foliar nutrient concentration were evident among the species aswell as within species, depending on the ontogenic stage of leaves, Both in mature andsenescent leaves G, scpiuni showed the highest concentration or nitrogen (3,5 I(I( and 2.4(1r.respectively) while M, indica had the lowest (1.42(1r and 0.41 (Ir. rcspcctivc ly). Significantinter-specific variation in nitrogen translocation efficiency (NRE) was observed (1'::= 0,(1).which varied 28.94 to 54,9YX, T ('(I1I({pa had the highest value while G, scpiutn had thelowest. M, indica (48,78'1r) T oricntalis (48,6Y'/c1 also had a relatively high NRE, NREs ofN. lappcceum. M, sapota, A, integritolia, A, altilis, A, auriculifonnis. M, peltata. A.nuingiun). A, scltolaris and P. ,lilliljm'o were 43,39, 42,57. 42.43. 41 ,X3, 40.41. 39,76. 36,XO._)4,53 and 31.XX%. respectively, P. gllojava had the highest concentration of phosphorousboth in mature (O,33X'X) and senescent (0,204'1r) leaves, As for potassium. M, sapota hadthe highest concentration both in mature (I ,07X'1r) and senescent (0,73'1r J leaves. Torientalis showed the highest phosphorous resorption efficiency (PRE). I.C, 62,7(Ir, whichwas significantly higher than that of N. lappaceutn (50,27(1r J, M, sapota (40,OY(Ir) and P.,lil/aja\'{{ (37,W1r.), M. sapota had the highest potassium resorption efficiency (32,99(1r)followed by T oricntalis (2Y,64(Ir), N. lappaccuni (26,97(1r) and P. glliljU\'(/ (2:~,55(;'), Butthey did not differ significantly, Possible implications of nutrient rctranslocation onadaptability of trees to nutrient limiting situations and succcssionnl development Indisturbed terrestrial ecosystems are discussed,