Tải bản đầy đủ - 0 (trang)
E. Shade Management in Cardamom

E. Shade Management in Cardamom

Tải bản đầy đủ - 0trang

250



K. P. PRABHAKARAN NAIR



1. Good canopy and cool temperature are maintained which protect the soil

from the scorching eVect of the sun. Shade also checks surface evaporation of soil moisture, thereby helping moisture retention for a longer

period, which is important to realize good yield.

2. Protects plants from sun‐scorching. On the border rows, where sunlight

falls directly, pest infestation has been noticed.

3. Checks high velocity of rainfall and minimizes mechanical damage to

plants, like splitting of leaves.

4. The network of root system of shade trees prevents soil erosion and

protects soil loss due to the beating action of rains, which leads to

improvement of the physical properties of the soil.

5. Maintains adequate humidity and soil moisture, which are essential for

proper growth, flowering, and capsule set.

6. Build up suYcient humus and organic matter and soil fertility through

the addition of leaf litter.

7. Act as a wind break and minimizes ill eVects of gale and heavy wind.

8. One or the other shade trees flower round the year and thus act as an

alternate source of nectar to honey bees, which are the principal pollinating

agents of cardamom. Forest areas ensure foraging capacity and availability

of nectar for a long period.

9. Shade trees provide congenial microclimate for proper growth and performance, help in checking weed growth, which otherwise would grow

luxuriantly in open areas and their control then would be major problem.



1. Ideal Shade Trees

In forest all kinds of trees are found, and they come in handy as shade trees.

In the cardamom hills of Kerala State, Karnataka State, and Tamil Nadu,

trees belonging to 32 families of Angiosperms constitute the major tree flora

(Shankar, 1980). An ideal shade tree in cardamom plantation should possess

the following characteristics.

1. A wide canopy to minimize the number of trees required for shade.

2. No flower shedding during pollination period so that pollination is not

adversely aVected.

3. Trees should be of medium size, evergreen which retain their foliage

throughout the year.

4. Trees should have small leaves and a well‐spread branching system.

5. To avoid competition for nutrients and water, the trees should be deep

rooted.

6. Trees must be fast growing to provide immediate and required shade.

7. Trees must have hard heartwood to withstand high‐velocity winds.



THE AGRONOMY AND ECONOMY OF CARDAMOM



251



A mixed population of medium‐sized trees, which facilitate shade regulation

and maintain more or less optimum conditions through the year, is desirable.

The principal trait to be looked into while selecting shade trees is adaptability

to the local climate, growth rate, and ease of establishment. Among the common trees, Balangi (Artocarpus fraxinifolius Wt), Nili (Bischofia javanica

Blum), Jack (Artocarpus heterophyllus Lamk), Red cedar (Cedrella toona

Roxb), Karimaram (Diospyros ebenum Koenig), Karna (Vernonia monocis

C.B. Darke) are desirable as shade trees for cardamom (Abraham, 1957; Rai,

1978). An introduction from Africa, Maesopsis eminii, is a very good shade tree

(Korikanthimath, 1983). Another introduction is silky (silver oak), Grevellia

robusta and this tree is now a very popular shade tree as well as stake for Black

pepper. The wood is hard and is a useful cabinet wood. Heterogeneity of shade

tree species and their characteristics is the major constraint to conduct investigations on shade requirements of cardamom. Certain studies have been carried

out to evaluate the usefulness of existing shade trees and identify the most useful

for cardamom (George et al., 1984). In this investigation, four important

species, such as Karimaram or ebony, Elangi (Spanish Cherry, Mimusops

elangi), Nandi or beatrack (Lagerstroemia lanmceolata), and Jack, have been

evaluated. Results indicated that cardamom plants grown under Karimaram

produced significantly more number and longer panicles and longer leaves,

yielding 40–50% more than those plants under other shade trees (Table XVIII).

Trees that carry crowded crown canopy are undesirable as shade trees as

they hardly allow filtered sunlight. Erythrina lithosperma and Erythrina

indica (Dadaps) are commonly planted by growers, especially when cardamom is planted in low‐lying areas but they are unsuitable as they compete

for nutrients and soil moisture (shallow rooted) and act as an alternate host

for nematodes.



2. Shade Requirements

Requirement for shade varies from place to place depending on the lay of

the land, soil type, rainfall pattern, crop combination, and so on (Abraham,

1965; Korikanthimath, 1991). In Guatemala, which receives well‐distributed

rainfall and has a cool climate round the year, cardamom is grown practically in open areas with either no shade or having only very sparse shade

(Anon, 1977). This is a major factor contributing to higher productivity in

the country.

Gaps in the shade canopy have almost always led to leaf scorching in

Indian conditions. It appears that the performance of cardamom plants

under Indian conditions depends on their interaction with shade, sunlight,

and soil moisture (Aiyappa and Nanjappa, 1967). Sulikeri (1986) in an



252



K. P. PRABHAKARAN NAIR



investigation on light intensity and levels of soil moisture on growth

and yield of cardamom reported that under high‐density planting (9000

plants haÀ1), yield was 1873 and 1928 haÀ1 under medium (40–45%) and

high (65–70%) light intensity respectively, as against 864 under low light

intensity (15–20%, Table XIX). Heavier capsules (75.6 g per 100 capsules)

were produced by plants receiving medium light intensity compared to those

receiving high light intensity 72.3 g per 100 capsules) and low light intensity

(71 g per 100 capsules). Harvest index (HI) under medium light intensity was

0.073 as against 0.066 under low light intensity and 0.037 under high light

intensity. This simply shows that it is important to regulate light intensity,

especially during rainy season, where overcast sky reduces light intensity. It

is equally important that shade trees put forth suYcient foliage and provide

adequate shade by the time summer sets in. The overhead canopy should,

therefore, be regulated once a year during May–June. With the denudation

of forests in the Western Ghats, the normal ecosystem is destabilized and the

microclimate and rainfall pattern in the cardamom‐growing tracts are vastly

changed. On the onset of the dry season (November–January) cool and

humid microclimate in the plantation changes rapidly as hot air wave from

the hinterlands pass across the cardamom tracts without much hindrance

due to deforestation all around cardamom pockets. As a consequence,

cardamom plants face inclement environment thereby resulting in poor

growth and consequent yield. Owing to high wind velocity, the transpiration

and evaporation rates will be increased. Moreover, plants suVer due to

physical pull of the blowing of high‐velocity wind. The enhanced evaporation

and transpiration deplete soil moisture rapidly.



3.



Pest Outbreak in Relation to Shade



The ecological upsets, especially the edaphic ones, have triggered the

pest problems in cardamom plantations. This is a consequence of the so‐

called ‘‘green revolution,’’ where the indiscriminate use of chemicals, both

fertilizers and pesticides, in the soil environment, has led to many environmental related problems and the outbreak of pests, that was once considered

minor, is assuming alarming proportions in many cardamom‐growing areas.

Among the insect pests, root grub is seen in exposed, warm, and less shaded

conditions and the insect has emerged as a major pest of cardamom in many

areas (Gopakumar et al., 1987). White flies likewise, are threatening the

cardamom plantations in many areas. Outbreak of locusts in Udubanchola

taluk in Idukki district of Kerala State is another example of the ill eVects of

changes in the microclimate (Joseph, 1986).



Light intensity



Moisture levels



Low

(5000–7000 Lux)



Medium

(15,000–17,000 Lux)



High

(25,000–27,000 Lux)



Control

Water at 25% ASM

Water at 75% ASM

Mean



706.50

945.90

941.22

864.54



1217.25

2030.22

2373.03

1873.50



645.75

2521.53

2618.88

1928.52



Treatment eVects

Main treatment

Subtreatment

Interactions

(a) Two levels of subtreatments

at a fixed level of main treatment

(b) Two levels of main treatments

at a fixed level of subtreatment



Significance



LSD ( p ¼ 0.05)

366.84

221.49



LSD ( p ¼ 0.01)

521.82

298.26



383.58



510.60



492.21



685.35



ÃÃ

ÃÃ

ÃÃ

ÃÃ



Mean yield

856.50

1832.55

1977.51

1555.52



Note: ASM, available soil moisture; ÃÃ, significant at LSD ( p ¼ 0.05); main treatment refers to moisture levels; subtreatment refers to light intensity.



THE AGRONOMY AND ECONOMY OF CARDAMOM



Table XIX

Dry Yield of Cardamom (kg/ha) as Influenced by Varying Light Intensity and Soil Moisture Levels



253



254



K. P. PRABHAKARAN NAIR



4.



Biorecycling



Among the plantation crops, no other has this benefit through the maintenance of tree growth in situ as cardamom has. As soil applied nutrients are

liable to leaching and loss, trees absorb them and cardamom is a good

example. Leaf fall aVects a recycling process of these minerals to upper soil

layer enriching soil fertility in the process.



5.



Water Requirements and Irrigation Management



In general, cardamom is grown as a rainfed crop, and cardamom‐growing

regions experience a dry spell of about 5–6 months in a year. Increased denudation of forests, deterioration in forest ecology, coupled with erratic trends of

rainfall leads to aridity eVects and adversely aVects cardamom production

(Ratnam and Korikanthimath, 1985). Even if there is no reduction in total

rainfall, failure of premonsoon and postmonsoon showers aVects the crop

adversely. During monsoon, postmonsoon, and winter months, although

there is suYcient moisture in the soil, plant growth is rather slow because of

low ambient temperature. During summer months, if adequate moisture is

available, cardamom plant puts forth luxuriant growth. Under normal conditions, panicles start emerging during January and continue to produce flowers

from May onwards. When postmonsoon rains fail and moisture stress precipitates, flower drop occurs and fruit set is hampered. Under severe conditions of

moisture depletion, drying up of panicle tips occurs. Therefore, irrigation is

necessary from January through May. In such a situation, determination of

adequate moisture for higher yield of cardamom needs no emphasis.

Raghothama (1979) studied the eVect of mulches and irrigation on sucker

production using two levels, 25% and 75% available soil moisture (ASM).

There was no separate control treatment in this investigation. Irrigation at

75% ASM showed enhanced performance of all growth and yield parameters,

including cardamom yield, but there was no statistical diVerence between this

treatment and 25% ASM. The diVerential eVects of the moisture level treatments were nullified by the eVect of mulching treatment and also due to

reduction in dry spell. Plants at higher irrigation level (75% ASM) produced

more and longer panicles, more number of internodes, higher number of

capsules, more fruit set, and higher capsule weight

Although cardamom requires high moisture level, it is very sensitive to high

water table and consequent water logging (Sulikeri et al., 1978). For better

growth, drains should be opened at regular intervals so as to keep the water

table 30 cm below surface. Sulikeri (1986) investigated the eVect of light

intensity and moisture level on the growth and yield of cardamom. Results

are in Table XIX. They indicate that irrigation at 75% ASM resulted in the



THE AGRONOMY AND ECONOMY OF CARDAMOM



255



maximum yield of 1977 kg haÀ1 which was more by 8% (1832 kg haÀ1)

compared to irrigation at 25% ASM and 31% more than that in the control

treatment. Light intensity had a very positive eVect and high light intensity

(25,000–27,000 Lux) increased yield by 123% compared to low intensity light at

5000–7000 Lux. It is also seen that in the control treatment there was yield

depression at the highest light intensity (25,000–27,000 Lux) compared to low

light intensity at 5000–7000 Lux. In the medium light intensity level at 15,000–

17,000 Lux, yield in the control peaked indicating that high light intensity

might, indeed, be detrimental when the other factors of production are missing.



6.



Irrigation Methods



Among the diVerent systems of irrigation, such as surface, subsurface,

overhead, trench, and sprinkler, the last one is most ideal in the case of

cardamom plantations.



7.



Sprinkler Irrigation



Overhead irrigation with sprinklers has many advantages. Cardamom is

grown on hill slopes with undulating topography and for such land, sprinkler system can provide uniform water supply. Since the rate of water supply

can be regulated, surface loss due to run oV and evaporation and conveyance

loss also are greatly minimized (Anon, 1985; Bambawale, 1980; John and

Mathew, 1977; Saleem, 1978; Vasanth Kumar and Sheela, 1970). This will

also preempt puddling, leaching, and run oV which are common with other

irrigation systems. The humid atmosphere required for the successful growth

and production of cardamom can be created by overhead sprinkling. Frequent light sprinkling can be done in soils of poor water‐holding capacity.

Irrigation equivalent to a rainfall of 4 cm, every fortnight would be quite

suYcient.

Installation of a sprinkler system should be processed after a careful

survey of the area for eYcient and economical design. A perennial source

of water is required nearby. Sprinkler systems are designed to meet specific

requirements, which may vary from one plantation to another depending on

the lay of the land, area to be irrigated, and source of water. The pumping

site should be selected in a convenient place which should cover the entire

area with least number of pipes. Portable units are more economical to use

but operation costs are slightly higher compared to the permanent system.

The main line and laterals can be made portable so that they can be moved

easily from one position to another.



256



K. P. PRABHAKARAN NAIR



Vasanthakumar and Sheela (1970) conducted field investigation on sprinkler system for two consecutive years. The field design was a split plot, with

irrigated and nonirrigated treatments as main plot and cardamom varieties,

Malabar, Mysore, and Vazhukka, as subplots. Results are in Table XX.

Results indicate that var. Vazhukka produced the highest panicle number

per clump (114.6) in the irrigated treatment compared to nonirrigated one

(90.8). Variety Mysore produced the least panicles in the nonirrigated treatment (51.8). All cultivars produced more flowers in sprinkler irrigated plots

(3048, 1894, and 3754 respectively in varieties Malabar, Mysore, and

Vazhukka, respectively) compared to the nonirrigated plots (26.4, 26.3,

27.6 in varieties Malabar, Mysore, and Vazhukka, respectively). Capsule

shedding was comparatively low in the irrigated plots (14.5%, 14.9%, and

11.7%, respectively in the three cultivars). Panicles of the irrigated plants

showed faster growth, the eVect being more pronounced in the variety

Vazhukka (115.8 cm as compared to 98.4 cm in the nonirrigated plants).

Even in the variety Mysore, which normally produced shorter panicles,

sprinkler irrigation increased the panicle length up to 73.8 cm whereas the

nonirrigated plants produced shorter panicles (54.0 cm). Percentage of capsules which reached final maturity was significantly influenced by sprinkler

irrigation in all the three varieties, Malabar, Mysore, and Vazhukka, which

showed 61.3%, 55.8%, and 62.5%, respectively in the irrigated plots. The

corresponding figures in the nonirrigated plots were 50.6%, 46.9%, and

52.7%, respectively for the three varieties, Malabar, Mysore, and Vazhukka.

Capsule yield almost doubled in the irrigated plots compared to the nonirrigated plots. Essential oil content of capsule was more in the irrigated plants on a

dry weight basis. Mean values for the irrigated and nonirrigated plots were

10.2% and 8.2%, respectively; the highest was in the case of variety Mysore

(12.2%) and the lowest in the nonirrigated plants (7.1%) in variety Malabar.



8.



Drip Irrigation



In situations where water has become scarce, drip irrigation, like sprinkler

irrigation has also become popular. The principle of the system is to use only

enough water needed for the crop and the drip irrigation became popular in

India after its great success in water‐scarce Israel. It minimizes water loss by

surface run oV, evaporation, and percolation to deeper layers. Since the water is

applied to the plant base, it is much more eYcient than conventional methods

of water use such as flooding. Water economy is the greatest advantage. For

cardamom, application of 10–15 liter water per day is suYcient. If the cultivation is done on the contour, it is easy to practice the system. Water from small

farm ponds can be drawn in this system without pumping. Drip irrigation has

80–95 eYciency (Kurup, 1978). However, the principal limitation of drip



Extension panicle growth

(cm) to total flowers borne

Cultivar



I



NI



Mean



I



NI



Mean



Malabar

Mysore

Vazhukka



101.3

73.8

155.8



78.5

54.0

98.4



89.9

63.9

127.1



61.3

55.7

62.5



50.6

46.9

52.7



56.0

51.3

57.6



Mean

‘‘F ’’‐test



110.3



76.97



LSD ( p ¼ 0.05)

Irrigation

Cultivars



Capsule fresh

weight (g)



Mature capsules (%)



59.87

ÃÃ



50.11

Ã



19.59

12.42

17.56



5.32

4.43

6.27



I



NI



Mean



1465 648 1061.5

757 421 589.0

1919 889 1404.0

NS



1380.33

ÃÃ

3.8

226

320



Capsule dry weight (g)

I



NI



Mean



353

189

446



154

107

213



253.5

148.0

329.5



656.0



158

ÃÃ



Essential oil content

I



NI



Mean



8.7

12.2

9.6



7.1

10

7.4



7.9

11.1

8.5



10.2



8.2

ÃÃ



67.40

52.94

74.86



Note: I, irrigation; NI, no irrigation; NS, not significant; Ã, significant at 95% confidence level; ÃÃ, significant at 99% confidence level.



0.47

0.59

0.83



THE AGRONOMY AND ECONOMY OF CARDAMOM



Table XX

EVect of Sprinkler Irrigation on Cardamom Yield and the Yield Components



257



258



K. P. PRABHAKARAN NAIR



irrigation is its initial cost for installation. It also depends on the plant spacing,

as closely spaced plants, as in the State of Karnataka, would involve higher

cost for installation than where spacing is wider. It would approximately cost

between Rs 25,000 and 47,000 (US$600–1100) per hectare.



9. Perfospray Irrigation

This is a type of irrigation in which water is sprayed under medium pressure.

In this system, aluminum or poly vinyl chloride (PVC) pipes of high density are

placed 6–9 cm apart and water is pumped into this at predetermined time

intervals. The setup can be shifted from one place to another and has been

found suitable for cardamom (Sivanappan, 1985).

10.



Contour Furrows Irrigation



Where water is on the highest point, taking advantage of the natural

slope, this irrigation can be set up. Contour furrows are opened and the

water is allowed to flow through them to reach the plants. If needed, small

basins around the base of the plants can be made. The system requires no

investment to set up. Water can also be stored in ponds or slopes along the

slope and used for irrigation in summer months.

11.



Time and Irrigation Frequency



In a sprinkler system, to get the eVect of 25‐mm rainfall, the system can be

operated once in 12–15 days time interval during May–June. Soil moisture

level should be above 50% of maximum water holding capacity. A stress

period for about 45 days during December–January has been found to be

quite beneficial. It would be ideal to commence irrigation during the first

week of February and continue at an interval of 12–15 days until regular

monsoon commences in the first week of June.

12.



Water Harvesting



Cardamom terrain, in many instances, undulates with moderate to steep

slopes. Quite a number of small and fairly big streams pass through many of

these areas. RunoV from cardamom watersheds can be collected in farm

ponds and check dams or underground water tapped through dug wells.

Harvested water can be stored in ponds and check dams by minimizing

losses through seepage, evaporation, and recycling. Apart from improving



THE AGRONOMY AND ECONOMY OF CARDAMOM



259



and stabilizing yields under rainfed cardamom cultivation, check dams, farm

ponds, and dug wells reduce flood hazards and recharge ground water. Such

devices in many cases will serve as percolation tanks that would substantially

augment the ground water availability in the area.



F. CARDAMOM‐BASED CROPPING SYSTEMS

An excellent example of forestry‐cum cash crop combination is the cardamom plantation. Some of the forests are uneconomical in view of the heavy

investments involved in building up adequate infrastructure for the extraction

and transportation of timber. Such forests, where cardamom plantation can be

established, will turn out to be economically viable. It is an environmentally

harmonious system as it will not upset or adversely aVect the environment or

the protective quality of the forest. Cardamom is, perhaps, the only plantation

crop which involves the least disturbance to the existing forest trees as against

partial felling of trees to raise coVee or black pepper.



1.



Sole Forest vs Cardamom Intercropped Forest: Economics

and Labor Utilization



The cultivation of cardamom beneath shade trees needs to be examined to

compare the benefits. An evergreen forest in the Western Ghats region managed ideally (sole forestry) can yield 10 m2 of timber per annum per hectare. The

Indian yields are much below this level. At present, the returns will be approximately 10 times more due to increase in timber cost. Moreover, clearing of

forests for nonforestry purposes is not permitted now by law. Computed over a

period of 20 years, the net pecuniary return from this will be Rs 700,000

(approximately US$16,300 in equivalence) and the job opportunities created

will be equivalent to Rs 500,000 (US$11,600 in equivalence) according to

Joseph (1978). If the area is brought under cardamom exclusively, the economic

benefit, at current yield expectations and ruling price of the produce, will be to

the tune of Rs 450,00,000 (approximately US$1.05 million) and the additional

creation of job opportunities to the tune of Rs 80,00,000 (approximately

US$1,86,000). In other words, a cardamom–forest mix could bring about

substantial economic advantage. Mixed crop of cardamom–coVee and black

pepper is called ‘‘multitier’’ cropping, as the plants attain diVerent heights, and

utilize sunlight, soil moisture and soil nutrients diVerentially. DiVerent types of

mixed or multitier crop combinations are discussed in a later section.



260



K. P. PRABHAKARAN NAIR



2. Mixed Cropping System

a. Nutmeg–Clove–Cardamom Combination. All the three crops, because

of their diVerent canopies, tap sunlight at diVerent heights and also,

because of their varied root systems, tap soil moisture, and soil nutrient

with diVering degrees of eYciency. In cardamom plantations, instead of

planting other forest tree species in the vacant areas, nutmeg, or clove or

both can be planted. The combination is both ecologically feasible and also

economically profitable. A good example of such a combination can be seen

in Burliar at an elevation of 1680 m amsl in Tamil Nadu. This plantation was

started as a nutmeg garden, later clove seedlings were planted in between the

nutmeg plants. Subsequently, cardamom seedlings were interplanted. Nutmeg and clove started to bear in about 6–7 years time after planting.

Although both of these plants require regulated shade in the early stages

of growth, clove does not require much shade once it starts to yield, and

clove and nutmeg can provide shade to cardamom seedlings in their early

stages of growth. Cardamom plants in this combination started to yield in

about 3 years time from the date of planting and gave a yield of about 150 kg

haÀ1 of dry capsules from 600 plants. Clove, on average, yielded about 1 kg

in dried form from a single plant. To meet the shade requirements of

cardamom, in addition to nutmeg and clove, tall growing shade trees at

regular intervals were retained in the garden. Sprinkler irrigation supplemented the shading eVect.

b. Cardamom–Arecanut (Areca catechu) Combination. Arecanut is

also a perennial crop like cardamom. The long prebearing age of the main

crop arecanut, small income from initial harvest, the risk of pests and disease

attack, remoteness from markets and inadequate transport support—all of

which are features of arecanut farming in the States of Karnataka primarily—

led to the evolution of introducing other crops in areca gardens (Abraham,

1956; Khader and Antony, 1968; Nagaraj, 1974). Until cocoa was introduced,

cardamom was the principal crop planted in areca gardens in southern

districts of Karnataka state. If one were to consider the unit value of diVerent

crop mixtures in arecanut garden, arecanut–cardamom is the best combination (Korikanthimath, 1990) at elevations between 700 and 1080 m amsl.

This is because at higher elevations arecanut is not successful. Normally

arecanut gardens at low‐lying areas on flat land with irrigation support are

most ideal for interplanting with cardamom. Investigations by Bhat and Leela

(1968) and Bhat (1974) have shown that more than 80% of the arecanut plants

have their root system confined to a radius of 75 cm from the base of the

palms, spaced at 2.7 m  2.7 m. Fourteen percent of the roots are at a radius of

25–50 cm and only 6% of the roots in a radius of 50–75 cm. Vertically,

cardamom roots penetrate to a depth of only 40 cm. Although both



Tài liệu bạn tìm kiếm đã sẵn sàng tải về

E. Shade Management in Cardamom

Tải bản đầy đủ ngay(0 tr)

×