12 KKU Researeh Journal
KKU Research Journal 2016; 21(3) : 12 - 27 http://www.tci-thaijo.org/index.php/kkurj/index
3KRWRV\QWKHWLFHI¿FLHQF\RI36,,DQGJURZWKRI\RXQJUXEEHU tree (Hevea brasiliensis) planted with Mucuna (Mucuna bracteata) cover crop
Anoma Dongsansuk 1,2*, Supat Isarangkool Na Ayutthaya1,2, Naruemol Kaewjumpa1,2, and Anan Polthanee1*
1Department of Plant science and Agricultural resources, Faculty of Agriculture, Khon Kaen University, Thailand, 40002 2Knowledge development of Rubber tree in Northeastern group, Khon Kaen University, Thailand, 40002 3Department of Biology, Faculty of Science, Khon Kaen University, Thailand, 40002 *Corresponding author, e-mail: [email protected] and [email protected]
Abstract Mucuna bracteata is a legume crop recommended for use as a cover crop to plant EHWZHHQURZVRI\RXQJUXEEHUWUHHVLQDQLQWHUFURSSLQJV\VWHP,WKDVPDQ\DGYDQWDJHV as a cover crop including its rapid growth rate, deep root system, drought tolerance and KLJKQLWURJHQ¿[DWLRQUDWH+RZHYHUWKHUHLVOLWWOHLQIRUPDWLRQUHJDUGLQJWKHSK\VLRORJLFDO UROHVSDUWLFXODUO\LQUHJDUGVWRHQKDQFHPHQWRISKRWRV\QWKHWLFHI¿FLHQF\DQGJURZWK performance, in which M. bracteata plants provide for the young rubber trees. 3KRWRV\QWKHVLVSDUDPHWHUVLQFOXGLQJ3KRWRV\VWHP,,HI¿FLHQF\FKORURSK\OOFRQWHQWWKH greenness or relative chlorophyll content of leaves (SPAD values) and growth of two-year-old rubber trees planted with or without M. bracteata were evaluated. The rubber plantation was situated at Khon Kaen University (NE Thailand) and the measurements were performed during the dry (March) and rainy (July) seasons in 2015. The results showed that the soil temperature in the experimental plot with cover crop ZDVVLJQL¿FDQWO\ORZHU WKDQWKDWLQWKHSORWZLWKRXWWKHFRYHUFURS,QFRQWUDVWVRLOPRLVWXUHFRQWHQWLQWKHSORW ZLWKWKHFRYHUFURSZDVVLJQL¿FDQWO\KLJKHUWKDQWKDWZLWKRXWWKHFRYHUFURS,QWKHGU\ season, the effective quantum yield of PSII, ǻFFm’DQGWKHPD[LPDOÀXRUHVFHQFHLQWKH light-adapted state (Fm’) of young rubber trees growing in the plot with the cover crop were IRXQGVLJQL¿FDQWO\KLJKHUWKDQWKRVHZLWKRXWWKHFRYHUFURS+RZHYHULQWKHUDLQ\VHDVRQ
ǻFFm’, and Fm’RIWKHUXEEHUWUHHVSODQWHGZLWKWKHFRYHUFURSZHUHVLJQL¿FDQWO\ORZHU WKDQWKRVHZLWKRXWWKHFRYHUFURSZKHUHDVRWKHUÀXRUHVFHQFHSDUDPHWHUVZHUHQRW GLIIHUHQW,QERWKVHDVRQVWKHFRQWHQWVRI&KORURSK\OOD&KORURSK\OO b and total Chlorophyll, SPAD values, leaf area and girth of rubber trees planted with the cover crop ZHUHVLJQL¿FDQWO\KLJKHUWKDQWKRVHZLWKRXWWKHFRYHUFURS7KLVVXJJHVWHGWKDWWKHXVHRI M. bracteataDVFRYHUFURSIRUWKHUXEEHUSODQWDWLRQZDVEHQH¿FLDOIRUJURZWKRI\RXQJ KKU Researeh Journal 13 rubber plants. M. bracteata provided a favorable environment for the plantation leading to higher chlorophyll content, increased photosynthetic performances and hence better growth of the young rubber trees Keywords : Photosynthesis, PSIIHI¿FLHQF\5XEEHUWUHH0XFXQD&KORURSK\OOFRQWHQW SPAD Introduction pubescens and Calopogonium caeruleum are commonly used as ground Rubber tree is an important economic cover in rubber cultivation. However, these crop in Thailand which is the second cover legumes are not always successful exporter country of rubber in the world after against weed growths during initial rubber ,QGRQHVLD5XEEHUWUHHVDUHWUDGLWLRQDOO\ cultivation (6). Thus, new cover planted in the South of Thailand where the legumes such as Mucuna pruiens, Mucuna environments were favourable for growth cochinchinesis and Mucuna bracteata have of rubber plants with generally very high been introduced. They are widely used in rainfall and fertile soils. During the last 0DOD\VLD,QGRQHVLDDQG6RXWK$PHULFD decade a large area of rubber plantation (6,8,9). Mucuna species are fast growing has been established in the Northeast legumes, with deep root system, drought of Thailand where the soils are of low WROHUDQWKDYHKLJKQLWURJHQ¿[DWLRQUDWHVDQG fertility, temperatures are higher, produce high biomass. They can reduce soil rainfalls are much less and many areas temperature and protect from soil erosion occasionally faces drought. These results ,QLQWHUFURSSLQJRUFRYHUFURSSLQJ are in low production potential of rubber in V\VWHPVWRWDOOLJKWXVHHI¿FLHQF\LQWKHPDMRU this part of the country. At present, applying crops as well as the associated crops can be fertilizers is the only practice that farmers enhanced. Higher yield of intercropped use to enhance plant growth and increase plants can be attributed to higher light rubber production. Planting cover crops XVHHI¿FLHQF\ ). The incident light in in between rows of young rubber trees the mixture canopies is intercepted by (intercropping system) has been each plant species (7). However, the suggested as another practice to photosynthesis characteristics in the mixed increase growth and productivity of FDQRSLHVLHWKHHI¿FLHQF\IURPOLJKW rubber tree plantation. Many interception to the conversion of energy researchers have reported the use of into biochemical energetic compounds, are several crop species as cover crop for young not well understood and documented. rubber trees. These include upland rice, &KORURSK\OO ÀXRUHVFHQFH LV mung bean, soybean and peanut (1); papaya, a powerful technique widely used to study tobacco, water melon (2); cassava and SKRWRV\QWKHVLVLQWKH¿HOGEHFDXVHLWLV peanut (3). Moreover, cover legumes a sensitive, real-time and non-destructive intercropped with rubber trees are also method (10). Chlorophyll pigments recommended for soil erosion control, absorb light energy and then drive improving soil fertility and soil quality, weed photosynthetic process (photochemistry), and pest control (4,5,6,7). The cover legumes release heat energy or re-emit such as Pueraria phaseoloides, Centrosema ÀXRUHVFHQFH 7KH RULJLQDO ÀXRUHVFHQFH 14 KKU Researeh Journal measurements under natural condition are area of 1 plot was 21 x 14 m with 21 IURPSLJPHQWVRISKRWRV\VWHP,, 36,, rubber trees and 24 M. bracteata plants. Soil DQGLWUHODWHVWROLJKWXVHHI¿FLHQF\RI type of the experimental plot was loamy sand. SKRWRV\QWKHVLV7KH36,,HI¿FLHQF\RI Fertilizer (N-P-K : 20-8-20) was applied at photosynthesis is expressed in mol of CO2 a rate of 100 g/plant twice a year in both converted or of carbohydrate formed (11). treatments (with or without M. bracteata as Therefore, our hypothesis is that the cover cover crop). Tillage and weeding control crops supply nitrogen to soil and that this were managed twice a year in both of nitrogen will be up taken by the treatments. rubber trees. Consequently leaf nitrogen, chlorophyll pigments and rubber tree Microclimate measurement photosynthesis can increase. High ,QWKHH[SHULPHQWDOVLWHPLFURFOLPDWH photosynthesis relates with plant growth. was measured during photosynthesis Thus, this research aims 1) to compare the and plant growth measurement in March 36,,HI¿FLHQF\DQGSODQWJURZWKRI\RXQJ (dry season) and July (rainy season) rubber trees (Hevea brasiliensis) planted 2015. Soil temperatures at 0-10 cm depth in the experimental plots with and without were measured using thermometer. Soil the legume, Mucuna bracteata as cover humidity was measured by weighing soil FURSDQG WRHYDOXDWHWKHEHQH¿WRI0 method. Soil samples were collected at 10 bracteata planted in between rows of young cm depth by soil core (5 cm diameter) and rubber trees. then weighed for fresh weight (FW). Soil o Materials and Methods sampled was oven dried at 150 C until constant weight or dry weight (DW). Soil Site and Plant material moisture content was calculated following This research was conducted the equation [(FW-DW)/FW] x 100 and unit in the Fruit Tree division at Faculty of reported as percentage. Air temperatures Agriculture, Khon Kaen University, and air humidity above ground surface at Thailand in 2015. The spacing of PKHLJKWZHUHPHDVXUHGZLWK,QGRRU rubber tree was 3 x 7 m. M. bracteata was digital thermometer-hygrometer (Minnesota planted in double row (spacing 3 x 3 m) 0HDVXUHPHQW,QVWUXPHQWV//&86$ 6RLO between rows of rubber trees (Figure 1). and air temperature, soil moisture content The trees were two years old when the and air humidity were sampled at 2 points, measurement started. We used one at 30 cm and another at 2 m from tree a randomized complete block design line (See Figure 1). (RCBD) with 4 replications (plots). The KKU Researeh Journal 15
Figure 1. Schematic diagram of the experimental plots showing plant spacing of rubber trees with (A) or without (B) M. bracteata as the cover crop. 'etermination oI chlorophyll Àuorescence bracteata plants/plot. As shown in equation (1) and (2), The following parameters of &KORURSK\OO ÀXRUHVFHQFH LQ WKH FKORURSK\OO ÀXRUHVFHQFH ZHUH PLGGOH OHDÀHW RI DWWDFKHG OHDYHV RI measured: F0PLQLPDOÀXRUHVFHQFHLQWKH rubber trees (3 leaves per plant) and mature dark-adapted state; F , steady state leaves of M. bracteata (3 leaves per plant) s ÀXRUHVFHQFHXQGHUDQDWXUDOLUUDGLDWLRQ F m, the ZDVPHDVXUHGLQWKHH[SHULPHQWDO¿HOG PD[LPDO ÀXRUHVFHQFH LQ WKH E\XVLQJD0LQL3$0ÀXRURPHWHU :DO] dark-adapted state, and Fm’, the maximal (IIHOWULFK*HUPDQ\ ,QRXUH[SHULPHQWZH ÀXRUHVFHQFHLQWKHOLJKWDGDSWHGVWDWH used two rubber tree plants/plot and two M. (natural irradiation). Maximal quantum 16 KKU Researeh Journal
yield of PSII photochemistry in dark A645 and A663 represent the absorbance condition (maximal photosynthetic of extraction at 645 and 663 nm, respectively.
HI¿FLHQF\ FvFm [equation (1)] and V and W represent the total extract volume effective quantum yield of PSII and the leaf fresh weight, respectively. photochemistry in light condition /HDIFKORURSK\OOZDVDOVRHVWLPDWHG SKRWRV\QWKHWLFHI¿FLHQF\LQQDWXUDO using a SPAD meter (SPAD 502 Plus condition), ¨FFm’ [equation (2)] were then Chlorophyll meter, Spectrum Technologies, determined as described by Schreiber (12). ,QF86$ 63$'XQLWLVDPHDVXUHRIWKH greenness or relative chlorophyll content
FvFm = (Fm - Fo) Fm...... (1) of leaves.
¨FFm‘ = (Fm‘ - Fs) Fm‘...... (2) Statistical analysis Plant growth The data per leaf (3 leaves/tree) and trees (2 trees/blocks) were averaged and the On the same leaves used for ANOVA done on 4 replications (blocks). The photosynthetic measurement, leaf area VLJQL¿FDQWGLIIHUHQFHVRISKRWRV\QWKHVLVDQG of rubber trees and M. bracteata was plant growth parameters between rubber PHDVXUHGXVLQJOHDIDUHDPHWHU /, trees planted with M. bracteata and only DUHDPHWHU/,&25,QF86$ *LUWKRI UXEEHUWUHHSODQWDWLRQDQGDOVRWKHVLJQL¿FDQW rubber trees was measured in March (dry differences of season in each species were season) and July (rainy season) 2015 at 1 analyzed by t-test at P < 0.05 using SPSS m above ground surface. version 17.0. Determination of chlorophyll content Results On the same leaves used for Microclimatic condition in the photosynthetic measurement, leaf intercropping system chlorophyll contents were measured as Microclimate information of the GHVFULEHGE\$UQRQ /HDIVDPSOHV experimental plot of rubber trees planted (0.1 g) were extracted with 80% acetone with and without M. bracteata in dry and DQG¿OWHUHGZLWK:KDWPDQ¿OWHUSDSHUV rainy seasons is shown in Figure 2. The The total extract volume was maximum soil temperature in dry season added to 10 ml by 80% acetone. The was measured at 30 cm (32.5 ± 0.4 oC) and absorbance of extraction was measured with the minimum was measured at 2 m (26.7 a spectrophotometer at 645 and 663 nm ± 0.1 oC) from the tree line (Figure 2A-B). using 80% acetone as a blank. Moreover, in both dry and rainy seasons, -1 soil temperature of the experimental plot Chl a (mg g ) = [12.7(A663) – 2.69(A645)] x (V / 1000W)…………...... …...(3) with cover crop at 2 m from tree line (Figure 2B) -1 ZDVVLJQL¿FDQWO\ORZHUFRPSDUHGZLWKWKDW Chl b (mg g ) = [22.9(A645) – 4.68(A663)] x (V / 1000W)…………...... …(4) ZLWKRXWWKHFRYHUFURS,QUDLQ\VHDVRQ Total chlorophyll (mg g-1) = [20.2(A )+ soil moisture contents in the experimental 645 plot with the cover crop at 30 cm and 2 m 8.02(A663)] x (V / 1000W)...... …(5) from the tree line were 10.5% (Figure 2C) KKU Researeh Journal 17 and 11.8% (Figure 2D), respectively which growing with the cover crop in both dry ZHUHVLJQL¿FDQWO\KLJKHUWKDQWKRVHLQWKH DQGUDLQ\VHDVRQVZHUHVLJQL¿FDQWO\KLJKHU plot without the cover crop. However, air than those grown without the cover crop WHPSHUDWXUHDQGDLUKXPLGLW\GLGQRWVLJQL¿- (Figure 5A-C). For M. bracteata, higher cantly differ between the two experimental total chlorophyll content was observed in plots (Figure 2E-H). the dry season compared to that in the rainy VHDVRQ )LJXUH) ,QDGGLWLRQLQERWKGU\ Photosynthetic characteristics in the and rainy seasons, SPAD values in leaves intercropping system of rubber trees planted with the cover crop Photosynthetic characteristics of ZHUHVLJQL¿FDQWO\KLJKHUWKDQWKRVHZLWKRXW rubber tree planted with and without as shown in Figure 6A. The mean SPAD M. bracteata were indicated by the values of M. bracteata were higher in the HI¿FLHQF\ RI SKRWRV\VWHP ,, PSII) rainy season compared with that in the dry season (Figure 6B). (ǻFFm’, FvFm, Fo, Fm, Fs and Fm’), chl a, chl b and total chlorophyll contents, and SPAD Plant growth in the intercropping system values. As shown in Figure 3, in dry season,
ǻFFm’ and Fm’ of rubber tree with Plant growth was expressed by leaf cover crop (0.652 ± 0.01 and 655 ± 26, area of the rubber trees and M. bracteata, UHVSHFWLYHO\ ZHUHVLJQL¿FDQWO\KLJKHUWKDQ and girth of the rubber trees as shown in those without the cover crop (0.56 ± 0.02 )LJXUHDQG/HDIDUHDRIWKHUXEEHU and 478 ± 60, respectively). Conversely, in trees planted with M. bracteata was 53.4 2 rainy season, the values of ǻFFm’ and Fm’ ± 5.8 cm in dry season and 54.6 ± 3.3 ZHUHVLJQL¿FDQWO\ORZHUZLWK cm2 in rainy season. These values were and 1540 ± 64, respectively) than without VLJQL¿FDQWO\KLJKHUWKDQOHDIDUHDRIUXEEHU the cover crop (0.622 ± 0.02 and 1758 ± trees planted without cover crop (33.48±1.38 45) as shown in Figure 3A and 3C. Other cm2 in dry season and 32.83±3.23 cm2 in
ÀXRUHVFHQFH SDUDPHWHUV VXFK DV Fv rainy season) as shown in Figure 7A. M.
F m, Fo, Fm and F s did not differ bracteataKDGVLJQL¿FDQWO\KLJKHUOHDIDUHD VLJQL¿FDQWO\EHWZHHQWUHDWPHQWVDVVKRZQLQ in rainy season (91.3 ± 4.5 cm2) than in dry Figure 3B, 3D, 3E and 3F. Fluorescence season (67.2 ± 2.8 cm2) as shown in Figure parameters such as Fo, Fm, Fs and Fm’ in M. %*LUWKRIWKHUXEEHUWUHHVZDVKLJKHU bracteataZHUHVLJQL¿FDQWO\KLJKHULQ when planted with than without cover crop the rainy compared to the dry season (Figure 8). (Figure 4C-F). Contents of chl a, chl b and total chlorophyll in leaves of rubber trees 18 KKU Researeh Journal
Figure 2. Microclimate condition, soil temperature, soil moisture content, air temperature and air humidity in dry season (March) and wet season (July) 2015. (A) Soil temperature at 30 cm from tree line, (B) soil temperature at 2m from tree line, (C) soil moisture content at 30 cm from tree line, (D) soil moisture content at 2 m from tree line, (E) air temperature at 30cm from tree line, (F) air temperature DWPIURPWUHHOLQH * DLUKXPLGLW\DWFPIURPWUHHOLQHDQG + DLU humidity at 2 m from tree line. Black vertical bars show data in plots of rubber trees without M. bracteata and grey vertical bars show data in plots of rubber tree with M. bracteata. The values are means ± SE (n = 7-8). (ND means not GHWHUPLQHG UHSUHVHQWHGWKHPHDQVVLJQL¿FDQWO\GLIIHUHQWDWS KKU Researeh Journal 19
Figure 3. &KORURSK\OOÀXRUHVFHQFHSDUDPHWHUVIRU PSII in the leaves of rubber trees planted without (black vertical bar) and with M. bracteata (grey vertical bar) in dry season (March) and rainy season (July) 2015. (A) Effective quantum
yield of PSII efficiency; ǻFFm’, (B) maximum quantum yield of PSII
HI¿FLHQF\ FvFm & PD[LPXPÀXRUHVFHQFHLQOLJKWDGDSWHGVWDWH Fm’, (D)
PD[LPXPÀXRUHVFHQFHLQGDUNDGDSWHGVWDWH Fm ( VWHDG\VWDWHÀXRUHVFHQFH
in light-adapted state; FsDQG ) EDVLFÀXRUHVFHQFHLQGDUNDGDSWHGVWDWH Fo. 7KHYDOXHVDUHPHDQV6( Q UHSUHVHQWHGWKHPHDQVVLJQL¿FDQWO\ GLIIHUHQWDWS 20 KKU Researeh Journal
Figure 4. Chlorophyll fluorescence parameters for PSII in the leaves of Mucuna (M. bracteata) planted in between rows of rubber trees in dry season (March) and rainy season (July) 2015. (A) Effective quantum yield of PSIIHI¿FLHQF\
ǻFFm’, (B) maximum quantum yield of PSIIHI¿FLHQF\ FvFm, (C) maximal
ÀXRUHVFHQFHLQOLJKWDGDSWHGVWDWH Fm’ ' PD[LPDOÀXRUHVFHQFHLQGDUN
adapted state; Fm ( VWHDG\VWDWHÀXRUHVFHQFHLQOLJKWDGDSWHGVWDWH Fs and
) EDVLFÀXRUHVFHQFHLQGDUNDGDSWHGVWDWH Fo. The values are means ± SE (n=4). KKU Researeh Journal 21
Figure 5. Contents of (A) Chl a, (B) Chl b and (C) total chlorophyll in the leaves of rubber trees planted without (monoculture system; black vertical bar) and with M. bracteata (intercropping system; grey vertical bar). Contents of (D) Chl a, (E) Chl b and (F) total chlorophyll in the leaves of Mucuna (M. bracteata) planted in between rows of rubber trees. The leaves were collected for chlorophyll measurement in dry season (March) and rainy season (July) 2015. 7KHYDOXHVDUHPHDQV6( Q UHSUHVHQWHGWKHPHDQVVLJQL¿FDQWO\ GLIIHUHQWDWS
Figure 6. SPAD values of (A) leaves of rubber trees planted without (monoculture system; black vertical bar) and with M. bracteata (intercropping system; grey vertical bar). (B) leaves of Mucuna (M. bracteata) planted in between rows of rubber trees. SPAD values were determined in dry season (March) and rainy season (July) 2015. The values are means ± SE (n=4). **represented the means VLJQL¿FDQWO\GLIIHUHQWDWS 22 KKU Researeh Journal
Figure 7. (A) Mean leaf area per leaf of rubber trees planted without (black vertical bar) DQGZLWK0XFXQD JUH\YHUWLFDOEDU % /HDIDUHDSHUOHDIRI0XFXQD (Mucuna bracteata) planted in between rows of rubber trees. The measurements were taken in March (dry season) and July (rainy season) 2015. The values are PHDQV6( Q UHSUHVHQWHGWKHPHDQVVLJQL¿FDQWO\GLIIHUHQWDWS
Figure 8. *LUWKRIWZR\HDUROGUXEEHUWUHHVPHDVXUHGDWPIURPJURXQG7KHUXEEHU trees are planted with (black vertical bar) or without (grey vertical bar) the cover crop Mucuna. The measurements were taken in March (dry season) and July (rainy season) 2015. The values are means ± SE (n=4). ** represented the PHDQVVLJQL¿FDQWO\GLIIHUHQWDWS KKU Researeh Journal 23
Discussion on light intensity and temperature (14,15).
0RUHRYHUǻ))m’ values of plants grown The objective of this present study LQWKH¿HOGDOVRYDU\GHSHQGLQJRQWKH was to compare physiological parameters environmental conditions at the time of such as photosynthesis and growth between measurement whether it is the full sunlight rubber trees planted with or without cover or partly cloudy, whether the measurement legumes and to assess the advantage of is done outside or under canopy, the light leguminous cover crop, M. bracteata LQWHQVLW\DQGWKHOHDIWHPSHUDWXUHV ,Q planted with young rubber tree. our studies, we found that air temperature First, in regards to microclimatic and light intensity near the canopy of the condition, the intercropping cultivation of rubber trees without cover crop at 30 cm rubber trees with M. bracteata reduced soil from tree line were 42 oC and 1,571 μmol temperature and increased soil moisture photon m-2s-1; and at 2 m from tree line content. The differences were statistically 41.1 oC and 1,433 μmol photon m-2s-1, VLJQL¿FDQWERWKGU\DQGUDLQ\VHDVRQV UHVSHFWLYHO\ LQ GU\ VHDVRQ ,Q WKH particularly in the area where the grounds rainy season, air temperature and light are covered with M. bracteata canopy intensity near the canopy of the rubber trees (2 m from the tree line). Chariachangel with cover crop at 30 cm from tree line (6,8) reported that leguminous cover were 33.4 oC and 460 μmol photon m-2s-1, plants planted with main plants function to respectively; and at 2 m from tree line 33.5 improve soil structure that leads to increase oC and 582 μmol photon m-2s-1, respectively. aeration and maintain moisture content. ,WFDQEHVHHQWKDWWKHDLUWHPSHUDWXUHLQWKH Sungthongwisate (9) also suggested that plot with and without M. bracteata in both ground covers increase soil moisture VHDVRQVZHUHQRWVLJQL¿FDQWO\GLIIHUHQW retention. Such improvement of soil +RZHYHUWKHUHZDVVLJQL¿FDQWGLIIHUHQFH conditions may improve rubber in light intensity near the canopy of the physiological status and growth. rubber trees growing with and without M. Photosynthetic characteristics of the bracteata. The difference in light intensity rubber trees planted with M. bracteata in the canopy of rubber trees growing with VKRZHGKLJKSHUIRUPDQFHLQRYHUDOO36,, and without the cover crop resulted in the HI¿FLHQF\ FKORURSK\OO FRQWHQW DQG GLIIHUHQFHLQǻ))m’ values particularly in SPAD value compared to those of the the dry season. This study showed that the single plant stands. The high values of ǻ))m’ values are positively related with the HIIHFWLYHTXDQWXP\LHOGRI36,,HI¿FLHQF\ chlorophyll content in the leaves of rubber ǻ)) ¶LQGLFDWHGWKHKLJKHI¿FLHQF\RIOLJKW m trees. Higher contents of Chl a, Chl b and use of rubber trees in natural conditions. total chlorophyll were found in the rubber ǻ)) ’ of leaves of the rubber trees growing m trees with M. bracteata compared to those ZLWK0EUDFWHDWDVKRZHGVLJQL¿FDQWO\ in the single crops. higher performance than those of the trees Chlorophyll is a typical pigment in growing without the cover crop in the dry photosynthetic organisms and Chl a and season, but not in rainy season. The levels Chl b are major pigments that are found in RIǻ)) ¶ZKLFKLQGLFDWHVWKHHI¿FLHQF\RI m JUHHQSODQWV *LWHOVRQ UHSRUWHG 36,,XQGHUOLJKWFRQGLWLRQYDULHVGHSHQGLQJ WKDWWKHFKORURSK\OOÀXRUHVFHQFHUDWLRVDUH 24 KKU Researeh Journal
linearly proportional to chlorophyll content. that N2¿[DWLRQE\3XHUDULDSKDVHRORLGHV As a result, the chlorophyll content and transferred to rubber tree exhibited highly FKORURSK\OOÀXRUHVFHQFH DVDQLQGLFDWRU UHODWLRQVKLSZLWKWUHHOHDI1,WV1¿[DWLRQ RISKRWRV\QWKHVLVRI36,,HI¿FLHQF\ DUH varied from 39% to 46% of tree leaf N. related and both of them are related to leaf ,QDGGLWLRQDODUJHSDUWRI1LQ nitrogen content. Saarinen (18) showed the leaves was also found in Rubisco that nitrogen content in needles of Pinus enzyme. Rubisco is an enzyme link between sylvestris is positively correlated with photosynthetic carbon reduction FKORURSK\OOFRQWHQWV,QDGGLWLRQVRLO (carboxylation) and photorespiratory nitrogen content also relates to leaf carbon oxidation (oxygenation) cycle. The nitrogen content. Yahan et al. (19) rate of carboxylation (Vc) and oxygenation reported that concentration of leaf (Vo) depends on the amount of activated nitrogen and phosphorus in 386 woody enzyme that are indicated by the maximum species at 14 forest sites across eastern velocity (VCmax and VOmax) (26). Moreover, the
China exhibited positive correlation with the maximum of electron transport rate (Jmax) concentration of soil nitrogen and phosphorus. is also a factor to limit carboxylation rate
*HQHUDOO\ OHJXPLQRXV FRYHU FURSV at the ribulose-1,5-bisphosphate (RuP2) supply the amounts of nitrogen needed for VDWXUDWHGUDWH ,WPHDQWWKDW0 various plants including rubber trees (20). bracteata provided the micronutrients e.g. Cover legumes improves soil physical nitrogen for the enhancing of growths in properties, increases soil organic matter both leaf area and girth of rubber tree. DQGDOVRLQÀXHQFHUXEEHUSURGXFWLYLW\ M. bracteata, is a legume used as a cover Conclusions in rubber tree or oil palm plantations to ,QWKLVVWXG\ZHUHSRUWIRUWKH¿UVW enhance soil organic matter, supply WLPHDGLUHFWHYLGHQFHRIWKHEHQH¿FLDO nitrogen, control soil erosion and increase effects of a legume cover crop (M. biomass production (6,8,9). Kothandaraman bracteata) growing with young rubber trees et al. (21) showed an increase in the contents on increasing photosynthesis performance of total N, available K and soil organic DVLQGLFDWHGE\DQLQFUHDVHG36,,HI¿FLHQF\ carbon at 30 cm depth in three-year-old under light adapted condition. Moreover, rubber tree intercropped with M. higher photosynthetic capacity correlated bracteata. Also, M. bracteata as a ground well with higher chlorophyll content and cover under oil palm increase soil fertility (22). better growth of rubber trees compared Kaewjumpa et al. (23) found that soils under with those growing without M. bracteata. the rubber tree planted with M. bracteata ,WPD\EHFRQFOXGHGWKDWWKLVFRYHUOHJXPH exhibited higher N content and non- provides a favorable microenvironment VLJQL¿FDQWLQFUHDVHLQRUJDQLFPDWWHU and additional soil nitrogen for the young organic carbon and exchangeable K. rubber trees. This intercropping system Moreover, legume cover crops provide can be suggested as an economical and N2¿[DWLRQDQG1WUDQVIHUWRWKHWUHHV12 environmentally friendly method for ¿[DWLRQE\OHJXPHFRYHUFURSVGHSHQGVRQ enhancing growth of rubber trees in the soil, climatic condition and legume species Northeast of Thailand. (24). Clermont-Dauphin et al. (25) reported KKU Researeh Journal 25
Acknowledgement (6) C h a r iachangel, M. The introduction and establishment We would like to thanks to of a new leguminous cover crop, “Knowledge development of Rubber Mucuna bracteata under oil palm tree in Northeastern group”, Khon Kaen in Malaysia. The Planter. 1998; University for research funding. We would 74(868): 363-368. also thank Miss Natenapa Sumthonglang (7) Malézieux E, Crozat Y, Dupraz for research assistant and Assist. Prof. & /DXUDQV 0 0DNRZVNL ' Dr. Kiriya Sungthongwisate for 2]LHU/DIRQWDLQH+5DSLGHO%GH supporting Mucuna (M. bracteata) plants. Tourdonnet S, Valantin- We would thankful Assoc. Prof. Dr. Piyada Morison M. Mixing plant species in Theerakulpisut for her proofreading. cropping systems: concepts, tools and References models. A review. Agron Sustain Dev. 2009; 29 (1): 43-62. /DRVXZDQ P, Yeedum ,Sripana &KDULDFKDQJHO0/HJXPLQRXV P., Sirisongkram, P. A study on cover plant-Mucuna Bracteata. The intercropping of young rubber Planter. 1998; 74(806): 359-368. , $UQRQ',&RSSHUHQ]\PHVLQ (20) Pushparajah, E. Nutrition and isolated chloroplasts. fertilizer use in Havea and Polyphenyloxidase in Beta associated cover in Peninsular vulgaris. Plant Physiol. 1949; Malaysia-A review. J Rubber Res 24: 1–15. ,QVW6UL/DQND. 1977; 54: 270-283. *HQW\ % %ULDQWDLV -0 %DNHU (21) Kothandaraman RJ, Mathews NR. The relationship between the AK, Krishnakumar K, Joseph quantum yield of photosynthetic K, Jayarathnam K, Sethuraj electron transport and quenching of 05&RPSDUDWLYHHI¿FLHQF\RI FKORURSK\OOÀXRUHVFHQFH%LRFKLP Mucuna bracteata D.C. and Biophys Acta. 1989; 990: 87-92. Pueraria phaseoloides Benth on *HQW\%+DUELQVRQ-%DNHU15 soil nutrient enrichment, microbial 5HODWLYHTXDQWXPHI¿FLHQFLHVRI population and growth of Havea. the two photosystems of leaves in ,QGLDQ-RXUQDO1DWXUDO5XEEHU photo respiratory and non-photo Research. 1989; 2: 147-150. respiratory conditions. Plant (22) Chariachangel, M. The introduction Physiol Bioch. 1990; 28: 1-10. and establishment of a new legumi- 7DL]H / DQG =HLJHU ( 3ODQW nous cover crop, Mucuna bracteata physiology. 4th ed. Sinauer under oil palm in Malaysia. $VVRFLDWHV ,QF 6XQGHUODQG Planter 1998; 74:363-368 USA; 2006. (23) Kaewjumpa N, Choosai C, *LWHOVRQ $$ %XVFKPDQQ & ,VDUDQJNRRO 1D$\XWWKD\D6 /LFKWHQWKDOHU+.7KH&KORURSK\OO *RQNKDPGHH66XQJWKRQJZLVHV Fluorescence Ratio F735/F700 K, Wongcharoen A. Effect of as an Accurate Measure of the different types of intercrops with Chlorophyll Content in Plants. rubber tree on some soil nutrients Remote Sens Environ. 1999; 69 (3): and soil fertility. Khon Kaen Agr J. 296–302. 2014; 42(3): 443-449. (18) S a a r i n e n T. Ch l orophyll (24) Broughton WJ. Effects of ÀXRUHVFHQFHDQGQLWURJHQDQG various covers on soil fertility under pigment content of Scots pine Heavea brasiliensis and on growth (Pinus sylvestris) needles in of the tree. Agro-Ecosystems. 1977; polluted urban habitats. Ann. Bot. 3: 147-170. Fenn. 1993;30(1): 1-7. (25) Clermont-Dauphin C, Suvannang., %HUU\-)DUTXKDU*7KH&2 Pongwichian P, Cheylan V, concentrating function of C4 Hammecker C, Harmand JM. 2016. photosynthesis. A biochemical 'LQLWURJHQ¿[DWLRQE\WKHOHJXPH PRGHO ,Q 3URFHHGLQJ RI WKH cover crop Pueraria phaseoloides 4th ,QWHUQDWLRQDO &RQJUHVV RQ DQGWUDQVIHURI¿[HG1WR+HYHD Photosynthesis. Reading, England, EUDVLOLHQVLV,PSDFWRQWUHHJURZWK +DOO'&RRPEV-*RRGZLQ and vulnerabirity to drought. Agric T. (eds) The Biochemical Society. Ecosyst Environ. 217: 79-88. /RQGRQ )DUTXKDU*'&DHPPHUHU69 Berry JA. A biochemical model of photosynthetic CO2 assimilation in leaves of C3 species. Planta. 1980; 149: 78-90.