RESOURCE MANAGEMENT FOR INTERCROPPING. WHITE YAM (Dioscorea rotundata Pair) IN COCONUT GARDEN

Transcription

1 ..i:) -U I' \. rv RESOURCE MANAGEMENT FOR INTERCROPPING \ WHITE YAM (Dioscorea rotundata Pair) IN COCONUT GARDEN BY SUJA, G. THESIS submitted in partial fulfilment of the requirement for the degree DOCTOR OF PHILOSOPHY Faculty of Agriculture Kerala Agricultural University Department of Agronomy COLLEGE OF AGRICULTURE Vellayani - Thiruvananthapuram 2001

2 CERTIFICATE Certified that this thesis entitled "Resource management for intercropping white yam (Dioscorea rotundata Poir) in coconut garden" is a record of research work done independently by Mrs. Suja)G. under my guidance and supervision and that it has not previously formed the basis for the award of any degree, fellowship or associateship to her. Vellayani, ~~--- Dr. V. MURALEED~~~AIR (Chairman, Advisory Committee) Professor and Head, Department of Agronomy, College of Agriculture, Vellayani, Thiruvananthapuram.

3 ABSTRACT Intercropping Asiatic yams'viz., greater yam (Dioscorea ala/a) and lesser yam (Dioscorea esculenta)jncoconutgardens is a common practice.the recently introduced African white yam (Dioscorea rotunda/a), despite its superior tuber yield and quality has not yet found an appropriate place in the coconut based cropping system. Field experiments were conducted at College of Agriculture, Vellayani during and to assess the performance of white yam variety Sree Priya as an intercrop in coconut garden, to evaluate. the effect of growth promoting substances on sprouting and to standardize plant population, settsizeand nutrientmanagementpracticesfor whiteyamunderintercroppingsituation. Five growth promoting substances(thiourea 2%, potassium nitrate 2%, IAA 1000 ppm,woodash andcowdungslurry)anda controlwereevaluatedfortheireffectson sprouting of white yam setts in CRD. Sett treatment using thiourea 2% induced early, uniform and better sprouting and established a vigorous crop. Factorial combination of three spacings (60x60 cm, 75x75 cm, 90x90 cm) and three sett sizes (100 g, 200 g, 300g) arranged in RBD comprised the second experiment. Planting white yarn setts of size 200 g at a spacingof90x90 cm so as to accommodate 9000 plants ha-lof coconutgardenresultedin bettersproutingand canopysize,higherharvest index, optimum tuber yield and higher profit. The response of white yamto three organic manures (FYM,coir pith compost and insitu greenmanuringusingsunhemp)assignedto mainplotsandcombinationofthreelevels each of nitrogen and potassium(40,80,120kg ha-i)apart fromnokocontrol in subplots was tested in split plot design.applicationof coirpith compostincreasedvine length,numberof functional leaves, LAl, leaf, vine, tuber and whole plant biomass,nar, CGR, and plant uptake ofn and K. Coir pith compostapplication led to marked improvements in tuber qualitybyenhancingdrymatter,starchandcrudeproteincontents.therewas no conspicuous

4 2 variation in HI,bulking rate, weight, length and girth of tubers and tuber yieldamong the organicmanures.thisimpliesthesuitabilityofcoifpithcompostandgreenmanureasalternatives to FYM, the common organic manure currently used. Higher ratesof nitrogennutritionpromoted all the abovegrowthattributes,though a declinein NAR and RGR valueswereobserved at harvest. Nitrogen supplyat higherrates also enhanced chlorophyll contents and interception of PAR at the active growth phase of the crop. Tuber yield response was pronounced upto 80 kg N ha-i. Higher rates of nitrogen enhanced dry matterand crudeprotein contents and loweredcrudefibre content in tubers. Moderatenutrition of nitrogenpromoted vitamin C content.n supplementationat higher rates favouredcropuptake ofn, P and K as well as enhancementof the availablestatus of N and K in the soil. Potassiumnutritionat 120kg ha-iretainedmaximum numberofleaves and favoured drymatteraccumulationin leaves,vinesandtubers.physiologicalparameterslikela!,nar, CGR, RGR and HI were also promoted by higher rates of applied potassium. Potassium at - higher rates favoured weight, girth and length of tuber and maximum tuber yield was obtained at 120 kg ha-i. Applied potassium at 120 kg ha-i yielded better quality tubers with appreciable starch content and lower fibre content. Vitamin C content of tuber was promoted by medium f potash nutrition. Higher rates ofk enhanced crop uptake ofn, P and K and at the same time respited in appreciable build up of available N, pand K in the soil. The balance sheet for available N, P and K indicated deficit balance. Green manuring enhanced the available N, P and K status of the soil profoundly, lowered net losses incurred in thenutrientbalancesheetsand promotedthe agronomicefficiencyofn and K fertilizers. EnhancedsupplyofN and K favouredgreater loss of the respectivenutrientsand lowered their use efficiencies, whereas addition of one nutrient at higher rates reduced the loss of the other nutrient and promoted its efficiency.

5 Application of coir pith t ha-ialong with 80 kg N, 60 kg PPs and 80 kg ~ 0 ha-i maintained higher tuber yield and generated higher profit from white yam under intercropping situation. To sum up, depending upon availability, FYM, coif pith compost or green manure can be used as organic manure with equal efficiency for white yam intercropped.. in coconut garden. The N:K ratio of 1:1 proved ideal. On the whole, coconut - white yam intercropping system proved profitable due to generation of net return ofrs. 31,525 ha-1and BCRof1.33.