CC BY
169
DOI https://doi.org/10.18551/rjoas.2016-10.02
THE CHARACTERISTICS OF NUTMEG (MYRISTICA FRAGRANS HOUTT) GROWTH USING AGROFORESTRY SYSTEM IN TERNATE ISLAND, INDONESIA
Tjokrodiningrat S.*
Faculty of Agriculture, University of Khairun, Indonesia
Ashari S., Syekhfani S., Aini N.
Faculty of Agriculture, University of Brawijaya, Indonesia
*E-mail: [email protected]
ABSTRACT
Nutmeg (Myristica spp.) is a high economic value spice crops which is spread on the whole area of Ternate Island, North Maluku province. Nutmeg is generally cultivated using agroforestry system with many varieties of populations and species which is supposed to influence the characteristics of nutmeg plants and micro climate. Thus, understanding the plant characteristics and microclimate of nutmeg plantation using agroforestry system is very important. Nutmeg plantation using agroforestry system is a mix between nutmeg as the main crop with other crops such as cloves, coconut and others. The focus of this research is to understand the characteristics of nutmeg, especially crop production components which cover the number and weight of seeds, microclimate as well as variations of population and diversity. This research employed observation method in which the sample was purposively set as many as 30 plants, using point-centered quarter sampling method. The results showed that agroforestry system affect the characteristics of nutmeg plants and the microclimate. The optimum plant population of 200 plants ha-1 with diversity of 1.38, had higher number and seed weight target-1 than the population of 100 plants ha-1 with diversity of 0.78 or population of 300 plants ha-1 with diversity of 0.82.
KEY WORDS
Nutmeg, production, plant characteristics, agroforestry, microclimate.
North Maluku Province, Indonesia, has long been known to the world as the center of nutmeg production, an indigenous plantation plant. Parts of nutmeg which have high economic values are seeds and mace because they can produce oil, grease, terpenoids and aroma (Bustaman, 2007). In Ternate Island, nutmeg is generally cultivated using agroforestry system in people plantation by mixing nutmeg as the main crop with other crops such as cloves, coconut, betel nut, jackfruit, durian, linggua, banana and others. Nutmeg plantation using agroforestry system in Ternate Island reaches around 3.616 ha where nutmeg as the main crop grown together with other crops on the same land (mixed-planting) with variety of populations and diversities of species per unit area. Variation of populations and diversity of plant species in an agroforestry system relatively affect crop production (Belote et al., 2011), in the form of facilitation, competition or neutral (Futakuchi 2007; Umrani and Jain, 2010) based on the availability of space and the use of resources, which in turn it is expressed through the characters of the plants such as branch, canopy and economic value (He et al., 2005; Khorshidi, et al., 2009; Tjokrodiningrat, et al., 2013; Pretzsch, 2014; Cinar and Tug, 2015; Di Zhang, 2015).
Nutmeg crop production in Ternate island is generally low and the variation among plantations is wide enough, ranges from 0:10 to 0:43 tons ha - 1 yr-1, similar to 1500-3000 trees -1 year - 1 (Hadad, 2009; Tjokrodiningrat, et al . , 2011) . The potential of nutmeg production reaches 5000 pieces per tree, at twice great harvest season in a year and the year-round production ( Hadad , 2009; Marzuki, et.al., 2006; Thankamani et al. 1994) . This condition recently becomes the concern of government and the nutmeg businessman (Tjokrodiningrat et al., 2011; Abdul-Madiki and Tjokrodiningrat, 2013). Productivity gap between locations is suspected to be related to population and diversity in every plantation.
Various studies revealed that agroforestry system in tropical area can be more productive than monocultures when the resources are optimally used (Michon et al., 1986; Cannell, 1991; Jin et al., 2009), due to the ability of agroforestry system in modifying the microclimate and protecting plants from strong winds as well as the contribution of its diversity to soil fertility and availability of nutrients such as nitrogen (N), phosphorus (P), potassium (K), carbon (C), soil acidity and production (Ong, 1991; Jin et al ., 2008; Rodriguez et al., 2011; Sumantra, 2012). Diversity can have positive effect on plants, although the population size and diversity of plants on an areal can lead to competition or otherwise facilitates the plant to modify themselves and the nature of symmetry (Ditzer et al., 2000; Weiner et al., 2001; Berger et al., 2007; Enquist et al., 2009; Damgaard, 2011; Pretzsch, 2014) depending on the resources condition, especially the number of nutrient and light (Kohli et al, 2008). Population and diversity, thus, at a certain level are able to deliver optimum results (Fangliang and Duncan, 2000; Wright, 2002; Ariapour and Afrougheh. 2008; Onrizal, 2009) and are expressed on the characters of the plant and production (He et al., 2005; Poorter and Bongers, 2006; Wardiana et al., 2008; Xu, 2009), as a response to population for both intra- and interspecific (Beland et al., 2003), which is controlled by the nature of plants, the ability of individual interactions, and the adaptability of plants (Berger et al., 2007; Makinde, 2009; Chalmers, 2014). The population becomes limit when there is overlap between canopy which indicates competition as expressed through plant performance (Wyxzomirski and Weiner, 2009).
Although there are many theories about population variation and diversity, the absence of data and information on the agro-ecological conditions of nutmeg plantation using agroforestry system limits researchers in underlying and generalizing the problem. Therefore, this study is very important to understand the characteristics of the nutmeg crop and the microclimate of the plantation in Ternate Island. This study objectively analyzed the condition of nutmeg agroforestry system based on population size and species diversity which made up a third of the plantation system, with a focus on the characteristics of nutmeg plants and micro climate. The results of analysis on each nutmeg plantation were used as a basis for resolving nutmeg crop production range problems.
METHODS OF RESEARCH
Location and Time. The study was conducted on a nutmeg plantation in Sulamadaha, Ngade, and Fitu Puncak Village, Ternate Island, North Maluku Province, at an altitude of 57358 m above sea level. The location is at the coordinates of 127'20'51 "- 127'20'55" East Longitude and 0.46'16 "- 0.46'21" North Latitude. Nutmeg plantation lies on an area with andisols and inceptisols soil type (Soil Survey Staff, 1999), pH 5.3-5.6 (Laboratory of Soil, Faculty of Agriculture, Brawijaya University, 2015). The Nutmeg plantation has variety of populations and plant species with Myristica fragrans Houtt type as the main crop. This kind of plantation has over half number of nutmeg plants from the total of all plant types. The research was conducted in two (2) phases. First, observation which was conducted in three districts of Ternate island for determining the location and samples. This observation was held from July to August 2013. Second, plant characteristics and microclimate measurement and analysis which lasted from October 2014 to June 2015.
Samples Choice. Each location consists of plantation crops, horticultural crops and forest plants which are dominated by productive nutmeg plants, Myristica fragrans, aged 2060 years based on the classification of Marcelle (1995) and Hadad et al., (1991; 2006; 2009). Nutmeg plantation using agroforestry system under study is described in terms of population and species diversity. The population consisted of plant density and diversity (H'), as the number of species in a plant community, calculated using survey applying the system of Arc-GIS (Arc-Info / Arc-View version 3.2). All trees with diameters of > 10 cm at the height of 1.5 m were calculated and recorded. Based on these calculations, data in each location was analyzed to determine the density, diversity, relative density and relative dominance (data was not shown) based on the method used by Arrijani (2008). Diversity was calculated using Shannon dominance index in Elzinga (1988), as follows:
n logn n - S fi logn fi
H' =---------------------(1),
n
Where: n = total number of plants, fi = number of plants in every species, and logn = natural logarithm.
Calculation of population size was used as a basis to determine three plantation categories which represent the general condition of nutmeg agroforestry system in Ternate Island. The three categories of the population were 100, 200, and 300 trees ha-1. Then, the diversity in each population category was analyzed. The obtained indices of diversity in a population of 100, 200, and 300 were respectively 0.78, 1.38, and 0.82 (Shannon index). The three locations have different cluster type plant distribution pattern. Representation of the three categories were defined in Ngade village with population of 100 trees ha - 1 and diversity of 0.78 (Agf1), in Sulamadaha village with population of 200 trees ha -1 and diversity of 1.38 (Agf2), and Fitu village with population of 300 trees ha -1 and diversity of 0.82 (Agf3)
Nutmeg samples were choosen purposively in which each study site consists of 10 trees per hectare, so that there were 30 samples of nutmeg trees used in this study. Each sample plant was observed in five microclimate points; four points at the east-west-north-south boundary of canopy and 1 point outside the canopy. Thus, there were 50 observation points at each location and total 150 observation points. A tree was also choosen as the central point using Point-Centered Quarter sampling method (Elzinga, 1988) with the help of line transects made on each nutmeg plantation. Transect line was made by drawing a line from north to south along 100 m with each transect line parallel to each other. In addition, two plots at 30 m x 30 m size were randomly created in each transect line. In the plot, the "central point" nutmeg was choosen. Plant character measurement was carried out on the central point sample and other plants in the plot.
Nutmeg Plant Characteristics and Microclimate. Plant characterization was conducted using phenotypic characteristics in IPGRI guideline (1980) as a descriptor record, expressed throughout the environment, and can be easily seen using eyes. Nutmeg plant characters were observed by measuring the following variables: Diameter Breast Height (DBH, cm), was known by measuring the trunk girth (LB) at 130 cm height from the base of the trunk (DBH130 cm) (Pretzsch, 2009; Mitchell, 2010); Basal area (BA 13, cm2), was calculated based on the DBH using the equation of BA=DBH2 x rc/4 (Anonymous, 2004; Pretzsch, 2009); Number of branches (Bn), were known by calculating all primary branches with a diameter of > 5 cm in a tree; Width of canopy (m), was measured based on the projection of tree crown on the east-west and north-south sides (Pretzsch, 2009); Height of tree (Ph, m), was known by measuring the distance of the stem to the top of the tallest tree directly using a roll meter; Leaf area index (LAI), was measured using a portable LAI-2000 plant canopy analyzer (Licor, USA). LAI measurement methods used were according to Mitchell, (2010) and Early and Wan-Isaac, (2008); Leaf chlorophyll index (LCI), was measured using a Minolta SPAD-502 leaf chlorophyll meter, following the method used by Liu and Yang (2012); Nutmeg production, ie the number of fruit (seeds of tree-1 yr-1) and fruit weight (kg tree-1 yr-1), was calculated per harvest time per tree at each harvest peak season. Fruit weighing was performed twice. First, the whole fruit was weighed along with the flesh of the fruit. Second, seeds were weighed with the maces which had been removed from the flesh of the fruit. The fruits ready for harvest were characterized by the split of some fruits in a tree, or the split of a fruit on a particular branch/twig/shoot.
Microclimate was measured inside and outside the plant samples in the components as follows: Solar radiation was measured using a digital lux meter AR813A; temperature (oC) and humidity (%) were measured using temperature and clock humidity HTC-1, measurements were taken at four points under the plant canopy, 0.5 m inside the line from outer crown projection at the height of 130 cm from soil surface, and at an open space outside the canopy at the same height. Measurement of solar radiation under the canopy (R1) and the radiation in the open space outside the canopy (R2) were performed to
determine the amount of radiation being held by the canopy (Rn), where Rn= R2 - R1. Intercept radiation value was calculated using the equation used by Sumantra et al., (2012):
Io -Iu
Ii =------------x 100% (2)
Io
where ^ is intercepted radiation, Io is the intensity of radiation under the canopy, and Iu is the intensity of radiation outside the canopy.
Radiation Use Efficiency (RUE , g / W m - 2) was calculated based on the relationship between the radiation intercepted by the plants (Ii) with above-ground biomass (ABG) (Rudorff et al., 1996) , as follows : RUE = ABG/Ii. The biomass was estimated based on the dry seeds weight on the three nutmeg plantations , using allometric equation according to Sutaryo (2009) which was derived from the equation Y=a Xb into Y=log a + b (log X), resulted on nutmeg biomass equation Y = 2.7931 + 0.8238 (log X), so that:
RUE = Y/Ii (3)
Rainfall (mm) was measured using rainfall measuring tool of modified ombrometer. The tool was placed in the open space within a half of the tree's height nearby, a night before the measurement. The Measurements were made every morning at 07.00 a.m.
Data analysis. To determine the effect of agroforestry systems (population and diversity) on nutmeg plant characteristics and microclimates, analysis of variance (ANOVA) was applied. When there is an effect, means different test using Duncan range test at the level of significance a = 0.05 is applied. Coefficients of variation (CV, %) was analyzed as an indicator of variability. The relationship between agroforestry plantation with nutmeg crop characteristics and microclimates was analized using correlation and simple regresion. To estimate the contribution of population, diversity and micro climate component to nutmeg crop production targets, stepwise procedure multiple linear regression method was applied (Sarle and Goodninght, 1982). To determine the maximum population, quadratic regression method was used. The data analysis was conducted using SAS ver. 9.1 (SAS, 2004).
RESULTS AND DISCUSSION
Characteristics of nutmeg plants at plantation using agroforestry system. Analysis of variance showed a significant effect of populations and diversity in the three nutmeg plantations using agroforestry system on the characters of nutmeg plants, namely branch number (Bn), leaf chlorophyll index (LCI), seed number target-1 (Snt), seed weight target-1 (Swt), DBH total (DBHp), BA targets (tree) (Bat), BA total (BAp), ILD, canopy width (CWd), but not including the plant height (Table 1). Duncan Range test showed that the most/biggest number of branches, DBH target (tree) (DBHt), total DBH, total BA and canopy width were found in agroforestry systems with 100 plants population ha-1 with diversity of 0.78 (Agf1) and it was significantly different with agroforestry system with 300 plants population ha-1 with a diversity of 0.82 (AgF2). The highest leaf chlorophyll Index, number of s-1, seed weight target-1, trees BA, number of branches and leaf area index were found in plabtation using agroforestry system with population of 200 plants ha-1 with diversity of 1:38 (AgF2) which was significantly different with Agf1 and Agf3 (see Table 2).
The effect of agroforestry systems based on population and diversity showed plant characters variations in particular seed number target - 1, seed weight target-1, branches number, canopy width and leaf chlorophyll index. Plantations with population of 200 trees ha -1 with diversity of 1.38 was the most optimum on seed number target - 1 and seed weight target-1. In addition, the effect of population and diversity was seen at the branches number, leaf chlorophyll index, BA tree-1 and leaf area index. The population of 200 trees ha -1 with a diversity of 1.38 (Agf2), was therefore considered to be more optimum to the plant character compared to the other two populations and diversities (Agf1 and Agf3).
Table 1 - Analysis of variance of the effect of plant population and diversity on the characters of the nutmeg plants in nutmeg plantations using agroforestry systems
Variable Mean Variation Coefficient Std Dev Minimum Maximum P > F
Seed number target-1 5590 34.293 4703 598.00000 16273 <.0001 hs
Seed weight target-1 16732 18.964 15577 1203 52267 <.0001 hs
Leaf chlorophyl index 36.04400 9.375 4.04908 29.78000 44.85000 0.0013 hs
Leaf area index 49.21167 19.385 13.3700 32.56000 76.53000 0.0028 hs
Basal area target-1 606.5180 14.067 103.846 360.1400 786.1400 0.0052 hs
Basal area total 2548 29.135 943.366 1413 5685 0.0006 hs
DBH target-1 29.75367 17.116 5.80586 24.52000 46.18000 0.0171 s
DBH total 720.5540 37.844 305.098 472.0500 1674 0.0262 s
Canopy width 10.05467 18.648 2.17301 6.15000 15.67000 0.0079 hs
Branch number 76.63333 26.594 29.1789 29.00000 160.0000 <.0001 hs
Plant high 14.02700 22.449 3.20797 9.64000 24.80000 0.2513 ns
Note: ns = non significant, s = significant, and hs = highly significant at level a=0.05.
Table 2 - The effect of plant population and diversity on nutmeg morphological characteristics
Nutmeg Plantation Ph Bn LCI Snt SWt DBHt DBHp BAt BAp LAI CWd
Agf1 Agf2 Agfa 15.107a 14.265a 12.709a 62.1b 108.5a 59.3c 36.863b 38.921a 32.348c 4214b 10649a 1908Dc 12561b 32.123a 5513c 33.729a 28.987b 26.545b 916.0a 691.5b 554.1b 523.81b 656.93a 638.82a 3462a 2202b 1979c 49.808a 57.576a 40.251b 11.702a 9.697b 8.765c
Note: Means with the same letters within columns indicate significant differences at the Duncan 0.05 Agfi = plantation with agroforestriy system with population of 100 trees ha-1 with diversity of 0.78 Agf2 = plantation with agroforestriy system with population of 200 trees ha-1 with diversity of 1.38 Agf3 = = plantation with agroforestriy system with population of 300 tress ha-1 with diversity of 0.82 Ph = plant high, Bn = branch number, LCI= Leaf chlorophyll index, Snt = Seed number target-1 (tree) SWt = Seed weight target-1 (tree) DBHp = DBH total, DBHt = DBH target (pohon), BAt = BA target (tree) BAp = BA total, LAI = Leaf area index, CWd = Canopy width
Table 3 - Stepwise procedure summary and the optimum model of morphological characteristic based on agroforestry systems of nutmeg plantation
Nutmeg Morphological Variable Number of Partial Model C(p) P>F
Characteristics entered Variabel In R-square R-square
Seed number target (Snt) Div 1 0.5456 0.5456 4.4822 <.0001 hs
Pop 2 2 0.0519 0.5975 3.0000 0.0729 ns
(4) Snt=--5346+14096div-14.34766pop (R2=0.5456) hs
Seed weight target (SWt) Div 1 0.8930 0.8930 7.3005 <.0001
Pop 2 0.0202 0.9132 3.0000 0.0184 s
(5) SWt=-14166+309804div-43.19979 (R2=0.9132)
Branch Number (Bn) Div 1 0.6110 0.6110 1.5308 <.0001 hs
Pop 2 0.0075 0.6185 3.0000 0.4725 ns
(6) Bn=0.8655+82.4138div (R2=0.6110) hs
BA total (BAp) Pop 1 0.4265 0.4265 4.7242 <.0001
Div 2 0.0695 0.4961 3.0000 0.0642 ns
(7) BAp=4884.05617-7.24010pop (R2=0.4961) hs
BA total-1 (BAt) Pop 1 0.2115 0.2115 5.9371 0.0106
Div 2 0.1219 0.3334 3.0000 0.0349 s
(8) BAt=367.21288+130.3785div+0.54898pop (R2=0.3334)
Leaf Chlorofil Indeks 0.2328 0.2328 13.4940 0.0011 hs
„ Div 1
(LCI) hs
Pop 2 0.2427 0.4755 3.0000 0.0015
(9) LCI= 33.46571+7.4405div-0.0241 pop (R2=0.4755) hs
Canopy width (CWd) Pop 1 0.3150 0.3150 1.5638 0.0013
Div 2 0.0140 0.3290 3.0000 0.4592 ns
(10) CWd=13.87350-0.01450pop (R2=0.3150)
Note: ns = non significant, s div = diversity.
significant, and hs = highly significant at level a=0.05. pop = population,
Multiple regression analysis with stepwise procedure showed that population and diversity simultaneously had significant effect (p < 0.05) on leaf chlorophyll index, seed
number target - 1 and seed weight target-1, as well as BA (Table 3). Linear relationship optimum model between plant characters, population and diversity can be seen in eq. 4-10.
In partial, diversity had significant effect on the branches number and seed weight number-1, while population had significant effect on the BA total and canopy width (Table 3). They also had a significant effect on seed weight target-1, BA total-1, and leaf chlorophyll index. In general, the contributions of diversity (55-89%) were higher than the population (2142%) on the character of the nutmeg plants. Seed number target-1, and seed weight target-1 increased by the maximum population and then decreased in further population increase (equation 11 and 12). At the maximum population (popmax 192 trees ha-1), 10.691 seeds weight target-1 were obtained (equation 11) and at popmax of 194 trees ha-1, the obtained seeds weight target-1 were 32.26 kg (equation 12):
Number of acorns-1, Y= -17397+291.98550pop - 0.75879pop2 (R2 = 0.5975; P>F = <.0001) (11) Seed weight-1, Y= -53175+888.20600pop - 2.30863pop2 (R2 = 0.9132; P>F = <.0001) (12)
Makinde (2009) reported that the population density has a significant effect on the character of jute plant height and environment humidity. Population rises up to a certain level can increase production (He, 2005; Di Zhang, 2015), but when the density increases in the average growth of the plants per population, there would be intraspesific competition (Makinde, 2009). Furthermore, Michelle et al., in Makinde (2009) stated that by nature, the competition between plants in a population can be ignored (not significant) until the population reaches a density threshold and the resource capability becomes limited. Nutmeg crop production on a population of 100 plants ha-1 was lower than on a population of 200 plants ha-1. Gradually, the seed number target-1, and the seed weight target-1 decreased along with the increase of population (equations 11-12), indicating the existence of interspecific competition. Oksanen (2006) and Shaukat (2009) stated that interspecific competition has very significant effect on most agronomic characteristics of plants.
Micro climate characteristics of agroforestry systems nutmeg plantation. Population and diversity had very significant effect on the component of microclimate agroforestry systems of nutmeg plantation (Table 4). Plantation with population of 200 plants ha-1 with diversity of 1.38 ( Agf2) showed relatively low temperature, relative humidity, light net , light absorption, and RUE which were significantly different from the population of 100 plants ha-1 with diversity of 0.78 (Agf1} but higher and significantly different when compared with the population of 300 plants ha -1 with diversity of 0.82 (Agf3) (Table 5).
Table 4 - Analysis of variance of population and diversity effect on the microclimate of nutmeg
plantation using agroforestry system
Variable Mean Variation Coefficient Std Dev Minimum Maximum P > F
Temperature (oC) 30.47767 0.596 0.32736 30.01000 31.33000 0.0002 hs
Relative Humidity (%) 73.70633 0.711 4.86750 67.26000 79.97000 <.0001 hs
Intercept radiation (Ii, Wm-2) 4.221667 1.415 0.08429 4.01000 4.34000 0.0001 hs
Radiation nett (In, Wm-2) 16958 12.71543 3076 10116 22044 <.0001 hs
RUE (g/W m-2) 948.2013 1.948 28.668 908.98 1021.00 <.0001 hs
Note: hs = highly significant.
The results of multiple regression analysis using stepwise procedure showed that the population had very significant effect (p < 0.0001) on the total radiation, intercept radiation, temperature, humidity, and RUE with contributions ranging from 52-99 %, whereas the effect of diversity on the four micro-climate components were not significant (p > 0.05) (Table 6). Optimum model of linear relationship between plant characters components with population and diversity can be seen in equation 13-17.
Agroforestry system is a land usage system which is most appropriate in supporting the growth of plantation crops with other crops simultaneously (De Zoysa, et al., 2014), with variations in population and diversity. Variations in population and diversity of agroforestry by Cannell (1991) can be set in five canopy layers, and each layer provides a variation on the
character of the plants and microclimate. At the optimum population and diversity (Agf2), it is known that the radiation nett, intercept radiation, temperature and relative humidity were significantly different from the two other plantations (Agf1 and Agf3). The effect of population and diversity to intercept radiation, temperature and relative humidity in the plantation system Agf2 iwas optimum compared to the character of nutmeg plants, especially the number of fruit and seed weight. Results of research on the character of nutmeg crop in the plantation with different population and diversity showed that most of the plant characteristics responded the increasing number of population in each nutmeg plantation.
Table 5 - The effect of agroforestry system (density and diversity) on the temperature, relative humidity, intercept radiation, and total radiation
Agroforestry system Temperature (0C) Relative Humadity (%) Intercept Radiation (Wm-2) Total Radiation (Wm-2) RUE (g/Wm-2)
Agfi 30.85a 67.96c 4.15c 1421c 976.41a
Agf2 30.41b 73.53b 4.23b 1695b 944.25b
Agfa 30.17c 79.63a 4.29a 1971a 923.94c
Notes: Means with the same letters within columns indicate significant differences at the Duncan 0.05 Agfi = plantation with agroforestriy system with population of 100 trees ha-1 with diversity of 0.78, Agf2 = = plantation with agroforestriy system with population of 200 trees ha-1 with diversity of 1.38, Agf3 = = plantation with agroforestriy system with population of 300 tress ha-1 with diversity of 0.82.
Table 6 - Stepwise procedure summary and the optimum model of microclimate
based on agroforestry system
... .. . Variable Number Micro climate . , . , . . entered Variabel In Partial R-square Model R-square C(p) P>F
Total Radiation (It) Pop 1 0.5523 0.5523 1.0002 <.0001 ns
(13) Tr=11453+27.5255pop (R2=0.5523) hs
Intercept Radiation (Ii) Pop 1 0.5244 0.5244 1.0778 <.0001
(14) Ir =4.07467+0..00073pop (R2=0.5244) hs
Temperature (T) Pop 1 0.7461 0.7461 3.5747 <.0001
Div 2 0.0221 0.7682 3.0000 0.1202 ns
(15) T =31.32550-.00337pop (R2=0.7461) hs
Relative Humidity (RH) Pop 1 0.9900 0.9900 3.0487 <.0001
Div 2 0.0007 0.9907 .0000 0.1638 ns
(16) RH=62.48448+0.05841 pop (R2=0.9900) hs
Radiation use efficiency Pop 1 0.5776 0.5776 1.6427 <.0001
(RUE) Div 2 0.0098 0.5874 3.0000 0.4297 ns
(17) Y=1010.4119-10.2164div-0.2603pop (R2 = 0.5874; P>F <.0001)
Note: ns = non significant and hs = highly significant at level a=0.05. pop = population, div = diversity.
Micro climate condition of each plant is also influenced by the interaction between the number and type of plants (Salazar et al., 2010). The effect is related to transpiration and chemical reactions, as well as the evaporation plant (He, 2005). C3 plant stomata are very sensitive to the relative humidity and contribute to the rate of photosynthesis and transpiration ratio (Da Matta in Pezzopene 2011; Pyakurel, 2014). Furthermore, Makinde (2009), Wyszomirski and Weiner (2009) state that the same species have similar ecological requirements so that the dependence of plants on the availability of space is very important and lack of it will lead to competition. Plantation AgF2 has higher diversity, number and weight of nutmeg crop seeds than the two other plantations. The diversity of plant characters can be positive for the plants (Pretzsch, 2014), influence the chemical litter, litter biomass, temperature and soil moisture (Eviner and Chapin, 2003; Eviner, 2004; Barbier et al., 2008). Various considerations in productivity improvements are expected to reach the standard maximum number of trees per hectare (Khorshidi, et al., 2009; Chalmers, 2014). Production of nutmeg in the population of 200 plants ha-1 and diversity of 1.38 is assumed to be better than the other two populations.
Correlation coefficient (r) between populations and diversity with the microclimate and plant components are presented in Table 7. The population was correlated with total radiation (0.74), radiation absorption (0.72), temperature (-0.86), relative humidity (0.99), BA
total (0.65), DBH total (0.51), and canopy width (0.56). While the diversity of plants was closely correlated with seed number target -1 (0.89), seed weight target-1 (0.94), and branches number (0.78). Seed number target -1 was closely correlated with branches number (0.78) and leaf chlorophyll index (0.58). Seed weight target-1 was closely correlated with the total radiation (-0.69), intercept radiation (-0.67), and leaf chlorophyll index (0.63). It is also known that there was a real or very real correlation between the characters of the plants, namely the number of branches with leaf chlorophyll index (0.52) and weight of 100 seeds (0.78). The weight of 100 seeds was also significantly correlated with radiation nett (0.69) and intercept radiation (0.67). Furthermore, temperature and RH was significantly correlated with BA total, DBH target, DBH total, and canopy width. The canopy width was also significantly correlated with total light and light absorption. The BA total was significantly correlated with the total radiation, temperature, and humidity. This fact explains that the components of microclimate and plant characters were correlated with population and diversity.
Table 7 - Coeffient correlation between plant morphological characteristics and microclimate based on population and diversity of nutmeg plantation
Population Diversity Bn It Ii T RH LCI
Population 1.0000 0.0596 ns 0.0398 ns 0.7431 s 0.7242 s -0.8638 hs 0.9950 hs -0.4630 ns
Snt -0.1739 ns 0.8975 hs 0.7874 hs -0.5073ns -0.2774 ns 0.0490 ns -0.2080 ns 0.5968 s
SWt -0.0857 ns 0.9449 hs 0.3738 ns -0.6959 s -0.6755 s -0.0522 ns -0.1154 ns 0.6321 s
LCI -0.4630 ns 0.4825 ns 0.5254 s -0.3878 ns -0.3595 ns 0.2964 ns -0.4780 ns 1.0000
LAI -0.2968 ns 0.4314 ns 0.4056 ns -0.2310 ns 0.1976 ns 0.1492 ns -0.3029 ns 0.4812 ns
Bap -0.6531 s -0.3021 ns -0.1812 ns 0.7958 hs -0.3199 ns 0.6279 s -0.6617 s 0.1683 ns
Bat 0.4598 ns 0.3759 ns -0.2674 ns -0.3232 ns 0.8112 ns -0.5596 s 0.4590 ns 0.2418 ns
DBHt -0.4924 ns -0.1254 ns -0.1417 ns -0.3294 ns -0.3556 ns 0.5994 s -0.54518 s 0.1312 ns
DBHp -0.5137 s -0.0976 ns -0.1286 ns -0.3578 ns 0.3264 ns 0.5854 s -0.52470 s 0.1291 ns
she -0.1910 ns 0.2248 ns 0.7816 hs 0. 6957 s -0.6755 s 0.2374 ns -0.2085 ns 0.2592 ns
CWd -0.5612 s 0.1516 ns -0.0739 ns -0.5354 s -0.5114 s 0.5216 s -0.5765 s 0.2249 ns
Bn -0.0398 ns 0.7817 hs 1.0000 0.1531 ns -0.1265 ns -0.0390 ns -0.0639 ns 0.5254 s
Ph -0.3104 ns 0.0347 ns -0.0218 ns -0.0366 ns -0.0044 ns 0.2957 ns -0.3209 ns 0.1918 ns
Note: ns = non significant, s = significant, and hs = highly significant at level a=0.05. Bn = branch number, It = total radiation, Ii = intercept radiation, T = temperature, RH = relative humadity, LCI= Leaf chlorophyll index, Snt = Seed number target-1 (tree), SWt = Seed weight target-1 (tree) DBHp = DBH total, DBHt = DBH target (tree), BAt = BA target (pohon), BAp = BA total, LAI = Leaf area index, CWd = Canopy width, Ph = plant heigh.
CONCLUSION
From the research has been conducted, it can be concluded that the variation of population and diversity in the agroforestry systems of nutmeg plantations affect the whole characteristics of nutmeg plant observed. Based on the results obtained in all three agroforestry systems, it is known that AgF2 with a population of 200 plants ha-1 gives more suitable growth space and microclimate for the nutmeg crop so that it can increase the number and weight of seeds compared to the plantation with higher population (Agf3) or lower population (Agf1).
Variations of population in the agroforestry system of nutmeg plantations determine the microclimate conditions. The results of analysis showed a significant relationship between the population and the characteristics of the microclimate. Furthermore, the microclimate affects the characteristics of the nutmeg crop. This research suggests that nutmeg plants tend to be shade-tolerant. Therefore, the nutmeg crop is suitable to be planted using agroforestry systems with optimum range of population and diversity.
Nutmeg plantation population correlates with all characteristics of the microclimate, and characteristics of the nutmeg crop for total basal area, total diameter at breast height (DBH), and canopy width. The diversity of nutmeg plantations was closely correlated with the characters of the plants, especially the seed number target-1 and sedd weight target-1 as well as the branches number. Thus, the characteristics of the plant and the microclimate respond the increase on the number of population in each nutmeg plantation. The effort in improving
nutmeg crop production requires a standard maximum number of trees per hectare. Based on the results of research on the agroforestry system of nutmeg plantation in Ternate Island, it is assumed that population of 200 plants ha -1 and diversity of 1.38 is better than the other populations.
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