Effect of Egusi Planting Density on Productivity of Egusi/Turmeric Intercrops in Southeastern Nigeria
Field trials were conducted at the Michael Okpara University of Agriculture Teaching and Research Farm, Umudike (Lat. 05°29N, Long. 07°33E), Southeastern Nigeria in 2008 and 2009 to determine the effect of egusi planting density on the productivity of component crops in egusi/turmeric intercropping system. Turmeric at 80, 000 plants ha-1 was intercropped with egusi three planting densities of 20, 000; 40, 000 and 66, 670 plants ha-1. The experiment was laid out as Randomized Complete Block Design (RCBD) with three replications. Across the planting densities, intercropping reduced egusi seed yield by 44% in 2008 and 43% in 2009. Similarly, on the average, intercropping reduced turmeric rhizome yield by 41, 53 and 57% at egusi planting densities of 20, 000; 40, 000 and 66, 670 plants ha-1, respectively. There was yield disadvantage as depicted by LER below unity (0.995) when turmeric was intercropped with egusi at 20, 000 and 40, 000 plants ha-1 and a yield advantage of 19% (LER = 1.19) when turmeric was intercropped with egusi at 66, 670 plants ha-1. Economic analysis (gross monetary returns) showed that sole turmeric was more profitable than sole egusi or egusi/turmeric intercrop at lower egusi planting densities. Comparative assessment of the mixtures indicated that it was better to grow the two crops separately.
Received: January 31, 2012;
Accepted: May 22, 2012;
Published: August 13, 2012
Egusi (Citrullus colocynthis L. Schrad syn Colocynthis vulgaris
Schrad) features prominently in the farming system of southeastern Nigeria while
turmeric (Curcuma longa L.) is a new crop in the region. Egusi is cultivated
as intercrop for its oil seed which is rich in protein, oil, essential amino-acids
and minerals (Ndukauba, 1998). In the cropping system,
egusi is always introduced as live mulch to control weeds as it provides early
vegetative cover which naturally suppresses weed growth during the initial growth
of the component crops (Anuebunwa, 2000). The reasons
for practicing mixed cropping by farmers include the production of higher total
yields from a given area of land, insurance against crop failure, reduction
in the levels of insect pests, diseases and weeds and better use of growth resources
among others (Okigbo and Greenland, 1976; Okpara
and Omaliko, 1995; Njoku and Muoneke, 2008). Although,
turmeric is a new crop, its integration in the farming system of southeastern
Nigeria is particularly important for most of the farmers and low income earners
for improved income and nutrition Turmeric is used in many countries as a spice
and cosmetic (Akanime et al., 2007). Curcumin
the main ingredient of turmeric functions as a medicine with anti-inflammatory,
anti-mutagenic anti-carcinogenic, anti-tumor, anti-bacterial, anti-oxidant,
anti-fungal, anti-parasitic and detoxifying properties (Akanime
et al., 2007).
There is dearth of published information on mixtures involving turmeric in
Nigeria. It is therefore, necessary to investigate the potentials of turmeric
intercropping with a view to improving the system. Huxley
and Maingu (1978) and Okpara et al. (2004)
reported that maximum productivity in intercropping could be achieved when inter-
and intra- crop competitions are minimal for growth limiting factors and the
density of each crop adjusted to minimize competition between them. Maximization
of yields in crop mixtures will always be on the basis of high species compatibility,
optimum plant population (Baker, 1974) and the minimization
of above and below ground competition for growth (Trenbath,
1976). The objective of this work was to evaluate the effect of egusi planting
density on the productivity of egusi/turmeric intercropping system.
MATERIALS AND METHODS
The experiment was carried out during the wet cropping season of 2008 and 2009 on an ultisol of Michael Okpara University of Agriculture Umudike. Umudike is located at latitude 5°29N longitude 7°33E and 122 m above sea level. Annual rainfall of the site was 2395.4 mm in 2008 and 2061.7 mm in 2009. Mean monthly air temperature ranged from 26 to 29°C in both years. The soil was a sandy loam and the chemical properties are shown in Table 1.
Egusi (Bara variety) and 15 g of turmeric (NCL 2 variety) were planted the same day on 12 May, 2008 and 19 April, 2009. The experiment was laid out as Randomised Complete Block Design (RCBD) with three replications. Plots measured 3x3 m (9 m2). Treatments were seven and comprised: Sole turmeric at 80, 000 plants ha-1, sole egusi at 20, 000 plants ha-1, sole egusi at 40,000 plants ha-1, sole egusi at 66,670 plants ha-1, 20,000 egusi plants ha-1 + 80, 000 turmeric plants ha-1, 40,000 egusi plants ha-1 + 80,000 turmeric plants ha-1 , 66,670 egusi plants ha-1 +80, 000 turmeric plants ha-1 . Egusi was sown at two seeds per hole on the crest of the ridges and the three egusi densities of 20,000; 40,000 and 66,670 were obtained with 1x1, 1x0.5 m and 1x0.3 m spacings, respectively. Turmeric rhizome was planted at both sides of the ridge (double row) at two per hole and at a spacing of 1x0.5 m to give a plant population of 80,000 plants ha-1 They received NPK fertilizer (20:10:10) at 200 kg ha-1 4 Weeks After Planting (WAP). Weeding of the plots was done manually with hoes at 1 and 4 Months After Planting (MAP).
Records were taken on number of fruits m-2, fruit weight and diameter,
number of seeds/fruit, seed weight, seed yield (kg ha-1) of egusi
and number of rhizomes m-2, rhizome weight and rhizome yield (kg
ha-1) for turmeric.
|| Some mechanical and chemical properties of the soil of the
experimental area in 2008 and 2009 cropping seasons
The data were analysed according to the procedure of a randomized complete
block design and treatment means were compared using least significant difference
(LSD 0.05). Land Equivalent Ratio (LER) [the sum of the ratios of
the yields of the intercrops to those of the sole crops (Mead
and Willey, 1980) was used to determine the productivity of the intercropping
system. Gross Monetary Returns (GMR) were determined based on the prevailing
market prices of 120.00 and 100.00 kg-1 in 2008 and 2009, respectively
for egusi seed and 1000 kg-1 for turmeric rhizome in 2008 and 2009
at the time of harvest. Genstat Release 4.23 Discovery Edition statistical software
package was used for the statistical analyses of the data.
Yield of component crops: Intercropping significantly reduced number of fruits m-2, fruit weight, number of seeds/fruit, weight of seeds/fruit, 100-seed weight and seed yield in both years (Table 2). Egusi seed yield reduction due to intercropping was 44 percent in 2008 and 43% in 2009. While number of seeds per fruit decreased, fruit weight and seed yield increased significantly as egusi plant density was increased up to 66, 670 plants ha-1 in the two cropping seasons. On the average, egusi seed yield at 66, 670 plants ha-1 was higher than the yield at 20, 000 and 40, 000 plants ha-1 by 123 and 54%, respectively. Interactions were significant for fruit weight and fruit diameter in 2009 but not significant for seed yield in both years. In both cropping systems in 2009, fruit weight was lower at 20,000 plants ha-1 compared to the higher densities of 40,000 and 66,670 plants ha-1 . However, fruit diameter in 2009 was higher at 20,000 plants ha-1 than 66,670 plants ha-1.
In both cropping seasons, intercropping with egusi drastically reduced the number and weight of mother, primary, secondary and total number of rhizome m-2 as well as rhizome yield/ha of turmeric (Table 3). Total number of rhizome m-2 was on the average, significantly decreased by 40,49 and 55% by intercropping at 20, 000, 40, 000 and 66, 670 plants ha-1 . Intercropping reduced average rhizome yield by 41, 53 and 57% at egusi planting densities of 20,000, 40, 000 and 66, 670 plants ha-1, respectively compared to sole cropping. Rhizome yield was generally higher in 2009 in which planting was done in April and the soil was more fertile than 2008.
||Effect of egusi density on yield and yield components of egusi
in egusi and turmeric intercrops at Umudike in 2008 and 2009 cropping seasons
|NS: Non significant, *Significant at 5%
||Effects of egusi planting density on yield and yield components
of turmeric in egusi and turmeric intercrops at Umudike in (2008) and (2009)
||Effect of egusi planting density on land equivalent ratio
and gross monetary returns on sole and intercropped egusi and turmeric intercrops
in (2008) and (2009)
|Egusi and turmeric were at prevailing market prices of
1000/kg, respectively in (2008) and (2009)
Efficiency of the mixtures: There were yield disadvantages of growing egusi and turmeric at lower egusi densities, especially in 2008 as depicted by the total LER 0.98 at 20,000 egusi plants ha-1 and 0.95 at 40,000 egusi plants ha-1 (Table 4). On average, LER at 20,000 and 40,000 egusi plants ha-1 was below unity (0.995). Intercropping at higher egusi planting density of 66,670 plants ha-1 resulted in slight yield advantage with average total LER of 1.19. The contribution of egusi to the LER was more at higher egusi planting densities of 40,000 and 66, 670 plants ha-1 but lower at the lower density of 20,000 plants ha-1 .
The gross monetary return of sole turmeric was substantially higher than that of sole egusi or egusi/turmeric intercrop. The average gross return of sole turmeric was higher than that of sole egusi by 45.6%. When averaged over both years, sole cropping of turmeric gave higher economic returns than intercropping at egusi planting densities of 20,000, 40,000 and 66,670 plants ha-1 by 315, 433 and 405%, respectively. Under intercropping, gross returns were lower at the higher egusi densities of 40,000 and 66,670 plants ha-1 compared with the lower density of 20,000 plants ha-1. The total monetary returns in intercropping were contributed considerably by the turmeric component as depicted by its higher partial monetary returns.
In both cropping seasons, seed yield of egusi was a reflection of the number
of fruits m-2, weight of fruits or seeds and was significantly influenced
such that the monoculture yields were consistently higher than those of the
intercrop. This agrees with findings on other crops (Muoneke
and Ndukwe, 2008; Njoku and Muoneke, 2008; Okpara,
2000; Manga et al., 2003; Ojikpong
et al., 2008), in which intercropping reduced yields due to competition
for growth resources. The observed increasing trend in seed yield of egusi with
planting density up to 66, 670 plants ha-1 , supports the findings
of Okpara et al. (2004), Mohdnor
(1980) and Ezedinma (1974). Egharevba
and Abede (1986) attributed the superior yields at high planting densities
to better water utilization as a result of less evaporation, better weed control
through canopy shading, better radiant energy utilization, increased photosynthesis
and improved leaf distribution. Ikeorgu et al. (1981)
had reported that egusi melon reduced soil temperature, soil moisture stress
and provided complete soil cover to check erosion when intercropped with cassava
and maize. Across planting densities, intercropping reduced egusi yield by 44%
in 2008 and 43% in 2009. Makinde and Alabi (2002) reported
60% reduction in melon seed yield in maize/melon intercropping.
Similarly, intercropping reduced rhizome yield of turmeric, with the magnitude
of depression depending on egusi planting density. For instance, intercropping
turmeric with 20,000 egusi plants ha-1 gave average rhizome yield
of 1973.5 kg ha-1 and a yield reduction of 41% when compared to average
sole crop yield of 3322 kg ha-1. However, increasing egusi density
to 66, 670 plants ha-1 reduced turmeric yield by 51%. The magnitude
of turmeric, therefore, increased with egusi planting density. Although turmeric
was the taller component in mixture, yield depressions were high. Muoneke
and Ndukwe (2008) had reported that when components are grown together,
severe mingling of their roots and the quest for below ground resources would
be high and that yield would be lower at high population because of severe competition
when the number of plants demanding the scarce resources was high. Rhizome yield
was generally higher in 2009 in which the soil was more fertile and the planting
date was earlier in April, indicating that soil fertility and planting date
may have played a role determining turmeric yield.
The LER is the land area that would be required for monocrops to produce the
yields achieved in intercropping. Using the LER as a means of determining the
productivity of the land, intercropping turmeric and egusi at the lower populations
of 20,000 and 40,000 plants ha-1 gave a yield disadvantage, with
average total LER lower than unity (0.995). However, when turmeric was intercropped
with egusi at 66, 670 plants ha-1 , a yield advantage of 19 percent
was obtained as reflected in average total LER of 1.19. Muoneke
and Ndukwe (2008) obtained similar results in okra/Amaranthus intercropping
The gross monetary returns further showed that sole cropping of turmeric was
more profitable than sole egusi or turmeric/egusi intercrop. With intercropping,
gross monetary returns dropped as egusi density was increased from 20,000 to
66, 670 plants ha-1 on the average. The average gross monetary returns
of 4, 914, 500 obtained with sole turmeric was 315 percent higher than in the
intercrop when egusi was sown at its best density of 20, 000 plants ha-1
(1,184,102). The implication of the monetary yield disadvantage is that it is
more profitable to grow the two crops separately. Similar findings were reported
by Chiezey et al. (2005) in sorghum soybean mixture,
with sole cropping of soybean being more profitable than sole sorghum or sorghum/soybean
The results of the study showed that it is more productive and more profitable
to grow sole turmeric in the study area.
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