Physiology Response of Soybean Variety to Various Types of Shading

in Agroforestry System

Muhammad Rizwan

, Abdul Rauf

, Rahmawaty

, Erwin Nyak Akub

Doctoral Student in Agricultural Science, Sumatera Utara University

Department of Agrotechnology, University Islamic Sumatera Utara

Agricultural Science, Sumatera Utara University

Faculty of Forestry, Sumatera Utara University

Keywords: Shade, Soybean Variety, Plant Physiology, Plant Growth.

Abstract: In mixed cropping patterns as in agroforestry systems, competition between crops and trees will occur. It

willspecifically occur for nutrient absorption and light for photosynthetic process, which often has a

negative impact on crop productivity. Field trial approach was used to examine adaptation of soybean

varieties to shade in each tree, namely: rubber, mindi, white teak, jabon, sentang. The test is done with a

Split plot design. The main plot is type of shading while subplots are soybean varieties. Treatment

composition in the first experiment on each factor (main plot and subplot) and type of plant is consisted of:

Main plot: P1 = Rubber shading, P2 = Mindi shading, P3 = Jabonshading, P4 = White Teak shading.

Subplot: V1 = Anjasmoro variety; V2 = Burangrangvariety, V3 = Dena-1 variety, V4 = Dena-2variety. The

finding of the research were: 1) Shading as the main plot have very significant effect on plant high except at

3 weeks after planting (MST), has very significant effect on flowering age of soybean; 2) The effect of

shading types on leaf chlorophyll parameters, both in the leaf tip, middle leaf, base leaf and total chlorophyll

is identical. Mindi, Jabon and white teak stands did not have significant effect each other, but all three

stands affect the chlorophyll content of soybean leaves compared to rubber stands, where the levels of soy

chlorophyll under this stand were the lowest.

1 INTRODUCTION

Indonesia has around 148 million ha (78%) dry land

and around 40.20 million ha wet lands (22%) of

188.20 million ha of total land area. However,

suitable land for agricultural purpose is only 76.22

million ha (52%) and most of such land is located in

lowlands (70.71 million ha or 93%) and the rest is in

highlands. In lowland areas, flat to wavy land (slope

<15%) that suitable for crop farming covers 23.26

million ha while on more sloping land (15−30%) is

47.45 million ha. In highlands, suitable land for

crops is only about 2.07 million ha and annual crops

are 3.44 million ha. Most of the dry land is scattered

in lowlands, namely area at an altitude of 0 - 700 m

above sea level (60.65%) and highlands located at an

altitude > 700 m above sea level (39.35%) (Hidayat

and Mulyani, 2002; Adimihardja et al. 2005;

Notohadiprawiro, 2006; Minardi, 2009).

Crops commodities development can also be

carried out on forestry land with technical

requirements and applicable policies. Forest area in

Indonesia reaches 180 million hectares, but most of

the area has experienced deforestation (forest

damage) due to ex-HPH (forest tenure rights) areas.

Of the total forest area in Indonesia, only 23 percent

or equivalent to 43 million hectares is still free from

deforestation, still maintained and as primary forests

(BPS Kehutanan, 2010). Forest areas and/or land

overgrown with trees, both forest and industrial trees

and fruits, are still widely available, especially in

residential areas and buffer zones as well as forest

areas. Inter-cropping areas is needed for land use

efficiency.

One of alternative for sustainable agricultural

development is to develop agroforestry systems.

Agroforestry is defined broadly as a farming or land

use system that integrates spatially and temporally

both tree and annual crops on an area. Agroforestry

is a type of land use that can maintain and increase

land productivity as a wholethat is a mixed activity

between forestry and agricultural activities, either

Rizwan, M., Rauf, A., Rahmawaty, . and Akub, E.

Physiology Response of Soybean Variety to Various Types of Shading in Agroforestry System.

DOI: 10.5220/0008887802250230

In Proceedings of the 7th International Conference on Multidisciplinary Research (ICMR 2018) - , pages 225-230

ISBN: 978-989-758-437-4

225

jointly or in rotation, which is adjusted to cultivation

patterns of local communities (King and

Chandler,1978;Wijayanto, 2002). Dry land

management, especially in watersheds, with

agroforestry systems is very necessary as a strategic

development resource, including: 1) dry land is the

largest cultivation area, 2) dry land can supply most

of the major commodities, and 3) dry land has

diverse commodities for agro-industry development

(Widaningsih, 1991; Suhara, 1991; Badrun, 1998).

In general, there are many obstacles in

developing agroforestry, among other low

productivity, due to lack of knowledge in the

selection of plant species and cropping patterns

management. According to Beets (Beets,1982), in

mixed cropping patterns as in agroforestry systems,

competition between crops and trees will occur,

especially for nutrient absorption, which often has a

negative impact on crop productivity. For this

reason, selection of plant species and cropping

patterns management in agroforestry must consider

physical, socio-economic, existing opportunities,

and farmer’s involvement in design and assessment

of cropping patterns to expedite the technology

adoption process. According to Thakur et al.

(Thakur et al.2005), farmers should choose annual

crops that have high economic value (cash crops),

food crops, medicines, herbs and even animal feed.

In addition, low productivity can also be caused by

radiation intensity stress due to canopy closure.

Several studies on ecophysiology of shading have

been carried out on upland rice (Chozin et al. 2000),

soybean (Sopandie et al. 2007), taro (Djukri, 2003)

and pepper (Wahid, 1984). The research shows that

the impact of light intensity stress is disruption of

photosynthesis rate which decrease plant metabolic

processes.

Intercropping is possible especially for food

crops such as sweet potatoes, corn, soybeans, and

upland rice, and horticultural crops such as

vegetables, flowers and fruits, as well as medicinal

plants such as turmeric, galangal, galingale, etc.

According to Asanawi and Ratna (Asanawi and

Ratna,2010), land use efficiency through

intercroping is very likely to be carried out as long

as fulfill plant growing requirements.

One of the cash crop commodities that require

intensive and important development is soybeans.

Soybeans have important role as source of vegetable

protein to improve nutritional level of the

community (Jufri, 2006). However, the community's

soybean needs cannot be fully met. Soybeans supply

tends to decrease in the period 2003-2007 (PDSIP

Ministry of Agriculture, 2016). In this period, the

availability rate decreased by an average of 3.37%

on annually basis. In the following year, it increased

again until 2011 to be 10.91 kg/capita/year or an

increase of 11.78% compared to the previous year of

9.76 kg/capita/ ear. The decline in availability was

occurred again in 2012, and continuing to 2014.

National strategy to increase soybean production

is formulated in the Source of Production Growth

which consists of five opportunities, namely: a)

expansion of harvest area, b) increasing

productivity, c) increasing yield uniformity and

stability, d) emphasis on yield gaps, and e) emphasis

on yield loss. In this strategy, increasing harvested

area is carried out by new land clearing, increasing

cropping index (IP), and soybean intercropping with

plantation and forestry crops (Adisarwanto et.al.

1997). However, efforts to increase production have

constrained by decreasing harvested area. In 2012-

2016, the average national harvest area decreases to

1.68% (PDSIP Ministry of Agriculture. 2016).

Therefore, research has been carried out to obtain

the best fertilizing dose for inter-cropping soybeans

grown along with forest tree.

2 METHODOLOGY

This research has been carried out in Arboretum of

USU KwalaBekala from January to December 2015.

Field trial approach was used to examine adaptation

of soybean varieties to shade in each tree, namely:

rubber, mindi, white teak, jabon, sentang. The test is

done with a Split plot design. The main plot is stands

while subplots are soybean varieties.

Treatment composition in the first experiment on

each factor (main plot and subplot) and type of plant

is consisted of: Main plot: P1 = Rubber shading, P2

= Mindi shading, P3 = Jabonshading, P4 = White

Teak shading. Subplot: V1 = Anjasmoro variety; V2

= Burangrang variety, V3 = Dena-1 variety, V4 =

Dena-2variety.

The linear additive model of the plan is used as

follows:



ijl

jililij

ABBYAKY











(1)

ijk

= the observational response of the

experimental unit that receive the Shading

factors, and j is the observational response

of the experimental unit that receive the

treatment on variety of soybean.

μ = general average

= the effect of the i-shading

= influence of the j-Variety of soybean

ICMR 2018 - International Conference on Multidisciplinary Research

226

(AB)

= the interaction effect of shading and variety

of soybean

ijk

= random effects of the i-shading and the j-

group

The data that obtained are analyzed by variance

in the level α = 0.05.If there is a significant effect,

then followed by the test of LSD for each treatment

group, the data analysis is performed with Microsoft

Office Excel program.

2.1 Observation

Observations were made on all intercrops and main

crops, which include growth, yield and production of

intercrops. The data was analyzed by analysis of

variance and then means difference will be tested

with Least Significant Differences test.

Observations made include the phase of plant

growth. Observation of the vegetative phase was

carried out by observing plant growth in each

experimental unit. Observations were carried out on

10 sample plants in each experimental unit. The

variables observed are as follows:

1. Plant height, observed once a week since 3

weeks after planting to flowering using meter

2. Flowering age (days), observed the first flower

formation

3. Leaf chlorophyll content

3 RESULT AND DISCUSSION

3.1. Effect of Shading

3.1.1 Growth Parameters

Shading as the main plot have very significant effect

on plant high except at 3 weeks after planting

(MST), has very significant effect on flowering age

of soybean (Table 1).

At 6 and 9 MST, the highest plant height found

in Jabon shading followed by Mindi, compared to

other stands. Both types of shading has significant

effect on plant height than Rubber and White teak

stand.

Board (Board,2000) states that in vegetative

growth, light quality and quantity can affect the

length, stem diameter and stem density of soybean.

Without considering photosynthesis, these two

factors affect plant development and morphology,

known as photomorphogenesis. For example, in the

same photosynthetic capacity, stem part that receives

more light will experience shorter elongation.

Table 1: Effect of shading types on soybean growth.

Shading Type

Plant High (cm)

Flowering

(DAP)

MST

Rubber (T1) 22,35 33,34

48,30

72,59

Mindi (T2) 23,68 36,49

53,42

47,57

Jabon (T3) 23,41 38,16

54,81

72,88

White Teak

(T4)

23,89 29,05

46,71

83,43

LSD 5% 2,26 4,82 6,22

Note: numbers followed by the same letter in the same

column are not significant different in the 5%

LSD test.

Light quality is determined by the ratio between

red light (R) and far red (FR) and blue light radiation

which in this case also affects the process of

elongation. This is due to etiolation process that

occurs during the stem elongation. It is suspected

that etiolation process that occur in shaded plants is

a way to capture light more efficiently. According to

Chairuddin etal. (Chairuddin etal.2015), increasing

plant height is an attempt to increase light absorption

because the plants are not able to raise the leaves

above the canopy.

With respect to production parameters, shading

has very significant effect on flowering age of

soybean. Soybean under Mindi shading (T2) show

faster flowering than other shading, on the other

hand, soybeans under white teak shading are the

slowest. Ballare (Ballare,1999), Morelli and Ruberti

(Morelli and Ruberti,2002), and Handayani

(Handayani,2003) stated that shading triggers

morphological and anatomical changes such as

stimulating hypocotyl growth and petiole lengths,

decreasing and developing leaves, reduce branching,

flowering acceleration and reduce reserves for

storage and reproduction. As a result, soybeans

under shading become more mature. Karamoy

(Karamoy,2009) stated that soybean grown in low

light conditions generally have faster flowering age.

Flowering process occurs due to presence of easily

soluble proteins (phytochrome). High light intensity

converts pigment into a form that initiates flowering

induction.

Such different result is thought due to differences

in shading intensity and microclimate conditions

such as air temperature and humidity at the study

site. According to Susanto and Adie (2006),

differences in climate and elevation have different

affect in plant life.

Physiology Response of Soybean Variety to Various Types of Shading in Agroforestry System

227

3.1.2 Physiology Parameters

In general, shading as the main plot and varieties as

subplots has different effects on physiological

responses (Table 2).

The effect of shading types (Table 2) on leaf

chlorophyll parameters, both in the leaf tip, middle

leaf, base leaf and total chlorophyll is identical.

Mindi, Jabon and white teak stands did not have

significant effect each other, but all three stands

affect the chlorophyll content of soybean leaves

compared to rubber stands, where the levels of soy

chlorophyll under this stand were the lowest.

Table 2: Effect of shading types on chlorophyll content of soybean leaves (unit / mm2).

Variable

Shading (T)

LSD

Rubber (T1) Mindi (T2) Jabon (T3) White Teak (T4)

Leaf tip chlorophyll 31,16

35,65

35,69

34,34

2,04

Middle leaf chlorophyll 27,89

35,91

35,53

33,88

2,59

Base lea chlorophyll 26,42

32,74

35,38

33,58

4,11

Total chlorophyll 85,47

104,30

106,61

100,04

8,80

Note: numbers followed by the same letter in the same column are not significant different in the 5% LSD test.

Plant adjustments to low radiation are

characterized by enlarged antennas for photosystem

II. The enlargement of the antenna for photosystem

II will increase the efficiency of light harvesting

(Hidema et al. 1992). Kisman (Kisman,2008) stated

tht chlorophyll a content is affected by light factors,

plastid inhibitors, and interactions between light and

inhibitors. While the content of chlorophyll b and

hypocotyl length is only influenced by light factors.

This shows that light factor has very dominant role

for chlorophyll content and hypocotyl length at early

growth of soybean. In soybean, leaves

photosynthetic character such as chlorophyll

content, ratio of chlorophyll a/b, and leaf area are

important characteristics for adaptation to shade

(Khumaida, 2002;Handayani, 2003;Jufri, 2006).

3.2 Effect of Varieties

3.2.1 Growth Parameters

Varieties have significant effect on plant height at all

observation time, namely 3 MST, 6 MST, and 9

MST (Table 3). The effect of different varieties

varies each week. The more age of soybeans is the

wider the difference in height for each variety.

Dena-1 variety has the lowest height, while

anjasmoro is the highest genotype. At 9 MST, plant

height of Anjasmoro, Burangrang, Dena-1, and

Dena-2 were 56.06 cm, 53.38 cm, 46.61 cm and

47.19 cm respectively. According to Balitkabi,

(Balitkabi,2012), plant height description of

Anjasmoro, Burangrang, Dena-1 and Dena-2 are ±

64-68 cm, ± 60-70 cm, ± 59 cm, and ± 40

respectively. The results of this study are close to the

description range of each variety, even the Dena-2

variety has exceeding the description. This shows

that such variety has an adaptation mechanism in

shaded conditions by increasing plant height.

Williams et al. (Williams et al.1976) stated that

reduced light received by plants will reduce root

growth, and plants exhibit etiolation symptoms by

increasing stem length at low light intensity.

Elfarisna (Elfarisna,2000) states that heavy shading

conditions (shade level50%) can increase plant

height, leaf area, and the amount of chlorophyll of

soybean, but reduce the number of branches, leaf

thickness, stomata density, filled pods, empty pods,

seed size and seeds weight per plant.

ICMR 2018 - International Conference on Multidisciplinary Research

228

Table 3: Effect of varieties on soybean growth.

Varieties

Plant Height (cm)

flowering (DAP)

3 MST 6 MST

9 MST

Anjasmoro(V1) 23,89

36,38

56,06

72,37

Burangrang(V2) 24,46

36,59

53,38

71,56

Dena-1 (V3) 21,88

31,81

46,61

67,13

Dena-2 (V4) 23,10

32,27

47,19

65,42

LSD 5% 1,51 2,20 3,22 4,07

Note: numbers followed by the same letter in the same column are not significant different in the 5% LSD test.

Each variety has different flowering age. The

fastest flowering ages are Dena-2, Dena-1,

Burangrang, and Anjasmoro, namely 65.42 DAP

(days after planting), 67.13 DAP, 71.56 DAP and

72.37 DAPrespectively. When compared with

flowering age description of each variety from

Balitkabi (2012), the results indicate that there is a

delay in flowering. Based on varieties description,

flowering ages for Dena-2, Dena-1, Burangrang,

and Anjasmoro are 35 days, 33 days, 35 days and

35-39 days respectively. This means that under

shaded conditions, all varieties experience delayed

flowering 2 times than normal flowering period.

Difference in flowering age of various varieties is

related to genetic diversity factors. Similar results

were also reported by Soverda et al. (2012) which

states that flowering age character of several

soybean genotypes is different.

3.2.2 Physiology Parameters

There is a significant difference of leaf chlorophyll

parameters among four varieties tested in the

adaptation mechanism to shade (Table 4).

Table 4. Effect of varieties on chlorophyll content of soybean leaves (unit / mm2).

Variables

Varieties (V)

LSD

Anjasmoro(V1) Burangrang(V2) Dena-1 (V3) Dena-2 (V4)

Tip chlorophyll 34,08

32,65

34,80

35,31

1,45

Midle leaf chlorophyll 33,17

32,03

34,45

33,57

1,39

Base leaf chlorophyll 32,63

31,05

32,99

31,45

2,11

Total chlorophyll 99,51

94,53

102,05

100,33

4,48

Note: numbers followed by the same letter in the same column are not significant different in the 5% LSD test.

One important strategy in improving the

efficiency of light use as an energy source is

increasing of leaf chlorophyll levels. Table 4 shows

that Dena-1 and Dena-2 have the highest chlorophyll

content compared to other varieties. Higher

increased chlorophyll in Dena varieties compared to

other varieties shows that this variety is more

effective in capturing limited light in shaded

environments. The higher Chlorophyll content in

shaded conditions is more optimal growth and

production potential, because 50% of light energy

can be transferred to the reaction centre through

chlorophyll (Croce et al. 2001). This is confirmed by

DjukriandPurwoko(DjukriandPurwoko,2003);

Soepandi (Soepandi,2013);Chairudin etal (Chairudin

etal.2015) that stated leaves formed at low light

intensity show an increase in the amount of

chlorophyll and contain chlorophyll a and b per unit

volume of chloroplast four to five times more and

have lower chlorophyll a/b ratio and decreasing non-

chloroplast pigment content such as anthocyanin

compared to full light because it has increased light

harvesting complex which increases light capture

efficiency for photosynthesis.

In high light intensity, the presence of photons is

abundant, thus affecting leaves ability to process the

light. In full light conditions, leaves ability to

process light must be greater than in low light,

consequently optimization of leaf function is more to

harvest light than to process energy (Atwell etal.

1999).

Physiology Response of Soybean Variety to Various Types of Shading in Agroforestry System

229

4 CONCLUSIONS

Tolerant Soybean (Dena-1 and Dena-2) and

sensitive soybeans (Anjasmoro and Burangrang) has

made adaptations to low light intensity under tree

stands (shading) by improve light capture capability

and use. Such adaptation is through anatomical-

physiological changes such as plant height,

chlorophyll content and flowering.

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