Annual Report 1961 - BEEP

-40--The efficiency of selection practised by thechoice of stalks of different calibres fromeither bunch planting or bunch potting isillustrated in fig. 13. The nine graphs in thisfigure correspond to the characters measured inthe bunch selection plot. In each, the meanvalue of groups of varieties is plotted againstthe various grades of selected stalks from whichthe members of each group were derived. Thusthe slope of the regressions of y on x (bunchselection plot value on single stalk grade),calculated separately for the bunch plantingand bunch potting samples, gives a figure forthe respective efficiency with which selectioncould be practised in each character by thechoice of stalks of different qualities in the previousgeneration.Measurements were made III the fieldduring the year on another bunch plantingexperiment designed to measure the superioritywhich would be expected in random selectionsfrom bunch planting if seedlings of poorquality arc discriminately eliminated. Resultshave yet to be calculated.(H)Progenies in contrasting environments.Seedlings of six crosses planted during 1959at the 4 Experiment Stations in randomiseddesigns with two standard varieties were measuredduring the year. Special thanks are due tothose students of the College of Agriculturewho helped with this work which was a morerefined repeti tion of an earlier experiment(GroRGE, [960) and endeavoured to assessadaptation exhibited by seedling progenies.At the time of writing most of the results ofthis work have been calculated. Among thefinding, which will be published elsewhere,estimates arc given of the expected efficiency ofselection in each environment for the characters,average length, average diameter, numberof canes, flowering intensity, brix and grade(the selector's appraisal of the worth of eachseedling). These estimates are being checked intwo other experiments which were planted withthe seedlings showing the best expression ofthe above characters in each cross and in eachenvironment. The response to selection will bemeasured in comparison with a random choiceof varieties from the six progenies at each place.These studies have suggested that a veryuseful method of parent-progeny evaluationwould be a factorial set of crosses where severalfemales arc crossed with the same males.Accordingly one such experimental comparisonhas been planted in the field at Reduit this yearwith progenies from the varieties Ebenc 1/37,C.B.38-22, N.Co. 376, P.R. 1000, M. 212/56crossed with M.147/44 and 47R2777.4. SELECTIONDuring the year canes grew well and mostof the trials could be harvested, resulting inmany selections. Recent changes in the programme,as described in the Annual Reportfor 1960, were incorporated in the selectionschemefor the first time. All seedlings, of theM./59 series selected from single plantings at the4 Experiment Stations (a total of 1100), wereeach propagated in two plots; one in the warmhumid area (Reduit and Pamplemousses S.E.S.)and one in the super humid region (Belle Riveand Union Park S.£.S.)Normal bunch planted seedlings of the 1960series were selected in virgins at PamplemoussesS.E.S. and at F. U.E.L. sub-station and theselected stalks were planted in bunch selectionplots at the same places. As selection inbunches is merely visual, well developed plantationscan be selected in virgins. Howevergrowth at Reduit S.£.S. and at Britanniasub-station was not satisfactory and selectionthere had to be postponed until the canes haveratooned in 1962.During this season it was concluded fromresults obtained from propagation plots, thatselection in virgins in these trials is not reliable.The present policy of selecting original plantationsin ratoons, does not seem to be a sufficientsafeguard against canes with weak ratooningcapacity entering propagation plots. A definiteassessment of at least the ability to grow wellin first ratoons is necessary and apart from a