Department ofhorticulture Lincoln University Canterbury

Size: px

Start display at page:

Download "Department ofhorticulture Lincoln University Canterbury"

Nora Greene
5 years ago
Views:

1 NUTRITION OF CONTAINER-GROWN TUBEROUS BEGONIAS M.B. THOMAS and H.S. NGU Department fhrticulture Lincln University Canterbury Abstract. Begnia x tuberhybrida was grwn in a peat:sand:sawdust(1: L1,v/v) ptting medium using a fur factr central cmpsite incmplete blck design t measure the respnse t N,P,Kfertilisatin and liming, each atfive levels. This plant respnded strngly t Nand P. Nitrgen was singularly the mst imprtant nutrient element and its effects were enhanced by P fertilisatin and liming. INTRODUCTION There is little published wrk n the nutritin f tuberus begnias butthey have beenshwn t respnd t mderate Nand cmparatively high K fertilisatin (7). Ithas als been shwn that higher N than K in a liquid feed gives the largest cntainer-grwn plants (4). The P requirement in bth cases was nted t be relatively lw. Results frm an earlier pt experiment at Lincln (unpublished) fund these plants t have a high N and a mderate P demand but were unrespnsive t K and liming. The study reprted here was initiated t determine the nutrient requirements f ptted tuberus begnias. MATERIALS AND METHODS Experimental Design. A fur-factr respnse surface prgramme fa central cmpsite design with incmplete blcks was used fr bth experiments as fr similar wrk (9). They invlved N, P, K and lime additins with 30 treatments, each with ten replicates. The nutrient levels and lime rates used in bth experiments are shwn in Figures 1 and 2. Fertiliser Rates and Ptting Media. The medium used was equal parts Hauraki sphagnum peat, carse sand, and untreated Pinus radiata sawdust. Nutrient levels were supplied frm Osmcte (26%N), superphsphate (8%P) and ptassium sulphate (39%K). Liming was based n a mixture f dlmite and agricultural lime (3: 1 w/w) while trace elements were applied frm "Sprumi~A" (150glm 3 ) and''sequestrene irn chelate" (75g1m 3 ). 370

Plant Material and Envirnment. Seedlings fr Experiment A (mixed clurs) and f cultivar, 'Gld Plate' fr Experiment B were pricked ut individually int 1.8 litre planterbags n December 8.

2 Plant Material and Envirnment. Seedlings fr Experiment A (mixed clurs) and f cultivar, 'Gld Plate' fr Experiment B were pricked ut individually int 1.8 litre planterbags n December 8. Final harvest fr Experiments A and B ccurred after 20 and 21 weeks, respectively. Plants were placed ina heated glasshuse with minimum temperatures f 8 0 C and fans set t perate when temperatures exceeded 22 0 C. DataCllectin. Visual ratings ffliage quality and vigur were carried ut using a grading system based n plant appearance (0 = dead, t 5 = tp grade and quality). Fliage clur was similarly assessed (0 = white, r very chlrtic, t 5 = green and healthy). Flwer numbers per plant, fliar dry weights, and tuber measurements were als btained. Nutrient levels and fliar dry weights were btained by the methds previusly reprted (9). Data frm the experiments were statistically analysed fr analysis f variance and F test. Datapresentedingraphic frm inthis paper was cmputed frm the equatins f the respnse surfaces. RESULTS The results in the tw experiments indicated similar respnses (Table 1) althugh mre interactins between nutrient additins and their grwth respnses ccurred in Fliage Grwth and Flwering. Nitrgen strngly influenced the develpment f leaves and flwers (ratings at 8 weeks after ptting) with ptimum quality and highest respnses at the 450 t 600g N/m 3 level (Table 1). It was further shwn in Experiment B that fliage grwth can be further enhanced by added P. The respnse surface (Figure 1) shwed that highest fliar dry matter ccurred when high N was cmbined with high P additins. Fliage grwth and flwering were mst benefited by a rate f 200g P/m 3 in Experiment A (Table 1). The respnses t ptassium and lime were much less significant than t Nand P (Table 1). There was n psitive influence n fliage grwth rflwering by K additins except when n lime was added in Experiment B (Figure 2) where the ph was 5.0. Additins flime raised the ph t as high as 6.5 with the 12 kg/m 3 lime rate but there were few significant effects ther than the very lw fliar dry weight respnse shwn in Figure 2 where K and lime were added at the highest rates. Tuber Grwth and Nutrient Analyses. Tuber grwth in bth exp~rimentswasinfluenced by all added nutrients and particularly N fertilisatin (Table 1). Phsphrus strngly enhanced the effect f N n tuber fresh weights (Experiment B, Figure 3) s that the heaviest tubers were at the tp rate f N and at least 200 g P/m 3 The cmbinatin f the highest N and lime additins als yielded 371

3 the heaviest tubers (Experiment B, Figure 3) while thickness and diameter were als maximised by high N (Table 1) and in the presence fhigh lime (Experiment B, data nt shwn). Ptassium fertilisatin shwed n psitive influence n tuber grwth. Table 1. Effects f nitrgen and phsphrus n fliage, tuber grwth, and flwering f tuberus begnias (Experiment A) and significance levels fr significant factrs nly in Experiments A and B. (***p<o.ool; **p<o.ol; *p<0.05; #=0.05 t 0.1) Term Fliage Fliage Fliage Max. Max. Tuber Flwers vigur clur dry tuber tuber fresh per rating rating weight thicknessdiameter weight plant (g) (em) (em) (g) Experiment A N (g m- 3 ) 0 1.6*** 1.8*** 1.0*** 1.5*** 2.6*** 9.2*** 1.6*** P (g m 3 ) 0 2.4*** *** 1.8*** 3.1 *** 10.6* ** 1.8*** K ** Lime ** Interactins CV% Experi'ment B N *** *** *** *** *** *** P ** ** ** K Lime # Inter- NxP* NxP* actins KxLime* NxLime* NxLime* NxLime* CV% The nutrient levels in the tubers fr different elements were in the fllwing ranges (bserved values) N:0.98 t 2.37%, P:0.09 t 0.96%, K:1.23 t 1.47%, Ca:0.12 t 0.37%, Mg:0.14 t 0.37%. Cmputer analysis f tuber nutrient levels shwed a strng negative influence fliming n tuber P levels while N additins had a psitive effect. This resulted in tuber P beingat a minimum level 372

4 Figure 1. Interactin f Nand P additins n plant fliage dry weight (g). f 0.1 % when N 'and lime were highest, while in cntrast the maximum predicted value fr tuber P f 2.5 % was at nil lime and the highest rate f N , Lime kgm'3 Figure 2. Interactin f K additins and liming n plant fliage dry weight (g). 373

5 DISCUSSION The strnginfluence f N fertilisatin nfliage, flwer and tuber prductin cnfirms the wrk f thers (4,7). High K rates nly prmted fliage grwth at nil lime (Figure 2) and shwed little ther influence, which is in agreement with previus unpublished results with this plant at Lincln. Hwever, this cntradicts the general respnse f begnia and ther cntainer-grwn plants t K fertilisatin (5,6) and where flwering f sme pt plants was enhanced by high rates f K (1). Further wrk with a slw release frm f ptassium fertiliser wuld allw strnger cnclusins n K requirements. 46'5 Figure 3. Interactin f Nand P additins n tuber fresh weight (g). There was a strng psitive interactin between Nand P n bth fliage and tuber grwth which agrees with wrk n the flwering and crm prductin f ptted freesias (8). The influence f lime n tuberus begnias was dependent n the level f applied N. Liming at high N rates enhanced tuber grwth but at lw N it was detrimental t grwth. There appears t be a desirable balance between liming and P rates which, in turn, may influence the respnse t N. High liming can reduce P availability due t P cmbining with calcium and carbnate ins frm insluble salts (2,3). This'was cnfirmed in the present wrk where liming strngly depressed tuber P levels particularly at high N rates. Tuber fresh weight was enhanced when high N was cmbined either with high 374

6 P r high lime (Figures 3 and 4). It, therefre, seems pssible that all three additins at high levels f at least 600g N/m 3, 300g P/m 3 and liming at 6kg/m 3 (ph 6.4) shuld prmte high tuber yields fr this medium. Liming therefre appears t help t balance high N and pssibly P rates, althugh further wrk is needed t cnfirm this Figure 4. Interactin f N additins and liming n tuber fresh weight (g). Acknwledgements. We thank M. Spurway fr technical assistance, and Dalgety Limited fr the supply f Osmcte fertiliser. We are als grateful t A. Cx fr prviding begnia seedlings. LITERATURE CITED 1. Bdley, J.W. and N. Meyer The nutrient cntent f Bnnafln deluxe chrysanthemums frm juvenile t mature grwth. Frc. Am.er. Sc. Hart. Sci. 87: Buckman, H.O. and N.C. Brady, The nature and prperties j sils. Macmillan, New Yrk. 375

7 3. Bunt, A. C Media andrnixesjr cntainer-grwnplants. Unwin Hyman, Lndn. 4. Gabriel, R. and J.G. van Onsem The nutritinal requirements f yung tuberus begnias. Mendedeling Rijksstatin vr Sierplantetelelt, Melle. 27: Pawlwski, H.E The effects f Ca(NO a )2 and NH.NO a n the grwth f petunias, chrysanthemums, and begnias. I.Yield. Gartenbauwiss. 32: Pivt, D Manurial trials with begnia cv. Glire de Lrraine. Pepirneristes, Hrticulteurs, Mavaichers 156: Skalska, E A cntributin t the manuring f tuberus begnias. Acta pruhniciana 9: Thmas, M.B. and S.D. Mathesn The nutritin f cntainer-grwn freesias. Crnrn. Hrt. Nv: Thmas, M.B. and M.l. Spurway Nutritin fcntainer-grwn Rewa-Rewa (Knightia excelsa). Prc. Int. Plant Prp. Sc. 36: fi

ANSWER KEY FOR MATH 10 SAMPLE EXAMINATION. Instructions: If asked to label the axes please use real world (contextual) labels

ANSWER KEY FOR MATH 10 SAMPLE EXAMINATION Instructins: If asked t label the axes please use real wrld (cntextual) labels Multiple Chice Answers: 0 questins x 1.5 = 30 Pints ttal Questin Answer Number 1