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Resource management for intercropping white yam (diocorea rotundata poir) in coconut garden
lntercropping Asiatic yamsviz., greater yam (Dioscorea alata) and lesser yam (Dioscorea esculentalui coconut gardens is a common practice. The recently introduced African white yam (Dioscorea rotundata), despite its superior tuber yield and quality has not yet found an appropriate place in the co...
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| Формат: | Ph.D Thesis |
| Язык: | Undetermined |
| Опубликовано: |
Vellayani
Department of Agronomy, College of Agriculture
2001
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| Итог: | lntercropping Asiatic yamsviz., greater yam (Dioscorea alata) and lesser yam
(Dioscorea esculentalui coconut gardens is a common practice. The recently introduced
African white yam (Dioscorea rotundata), 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 1998-99 and 1999-2000 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,
sett size and nutrient management practices for white yam under intercropping situation.
Five growth promoting substances (thiourea 2%, potassium nitrate 2%, IAA 1000
ppm, wood ash and cowdung si urry) and a control were evaluated for their effects on 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 yam setts of size 200 g at a spacing of90x90 cm so as to accommodate 9000 plants ha' of
coconut garden resulted in better sprouting and canopy size, higher harvest index, optimum
tuber yield and higher profit.
The response of white yam to three organic manures (FYM,coir pith compost and
in situ green manuring using sunhemp) assigned to main plots and combination of three levels
each of nitrogen and potassium (40,80, 120 kg ha') apart from noko control in subplots was
tested in split plot design, Application of coir pith compost increased vine length, number of
functional leaves, LA!, leaf, vine, tuber and whole plant biomass, NAR, CGR, and plant
uptake ofN and K. Coir pith compost application led to marked improvements in tuber
quality by enhancing dry matter, starch and crude protein contents. There was no conspicuous
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variation in HI, bulking rate, weight, length and girth of tubers and tuber yield among the
organic manures. This implies the suitability of coir pith compost and green manure as alternatives
to FYM, the common organic manure currently used.
Higher rates of nitrogen nutrition promoted all the above growth attributes, though a
decline in NAR and RGR values were observed at harvest. Nitrogen supply at higher rates
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". Higher rates of nitrogen
enhanced dry matter and crude protein contents and lowered crude fibre content in tubers.
Moderate nutrition of nitrogen promoted vitamin C content. N supplementation at higher
rates favoured crop uptake ofN, P and K as well as enhancement of the available status of
N and K in the soil.
Potassium nutrition at 120 kg ha' retained maximum number ofleaves and favoured
dry matter accumulation in leaves, vines and tubers. Physiological parameters like LA!, 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' . Applied potassium at 120 kg ha' yielded better quality tubers with appreciable
starch content and lower fibre content. Vitamin C content of tuber was promoted by medium
potash nutrition. Higher rates ofK enhanced crop uptake ofN, P and K and at the same time
resulted in appreciable build up of available N, P and 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 the nutrient balance sheets and promoted the agronomic efficiency ofN and K fertilizers.
Enhanced supply ofN and K favoured greater loss of the respective nutrients and lowered
their use efficiencies, whereas addition of one nutrient at higher rates reduced the loss of the
othernutrient and promoted its efficiency.
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Application of coir pith compost @ 5 t ha:' along with 80 kg N, 60 kg P 2 0 5 and 80 kg
K, 0 ha" maintained higher tuber yield and generated higher profit from white yam under
intercropping situation. To sum up, depending upon availability, FYM, coir 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 l: 1 proved ideal. On the whole, coconut - white yam
intercropping system proved profitable due to generation of net return ofRs. 31,525 ha-land
BCRof1.33.
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