Effect of Stylosanthes guianensis and Upland Rice Intercropping Ssystem to Rice Productivity  

K. Songyikhangsuthor1 , B. K. Samson2
1. Northern Agriculture and Forestry Research Center (NAFReC), Houay Khot village, Xieng Ngeun district, Luang Prabang province, P.O.BOX 487, Lao PDR
2. International Rice Research Institute (IRRI), Lao PDR Office
Author    Correspondence author
Rice Genomics and Genetics, 2015, Vol. 6, No. 3   doi: 10.5376/rgg.2015.06.0003
Received: 27 Feb., 2015    Accepted: 28 Apr., 2015    Published: 01 May, 2015
© 2015 BioPublisher Publishing Platform
This is an open access article published under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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Songyikhangsuthor and Samson, 2015, Effect of Stylosanthes guianensis and Upland Rice Intercropping Ssystem to Rice Productivity, Rice Genomics and Genetics, Vol.6, No.3 1-5 (doi: 10.5376/rgg.2015.06.0003)


Upland rice grown with legume crop is thought to help in the nitrogen economy of the rice field, improve soil organic matter content through litter fall, and contributes to the control of weeds. Therefore, the objective of this study is to optimize establishment, survival of Stylosanthes plants and to achieve Stylosanthes biomass accumulation during fallow period for subsequent rice crop season, while minimizing competition with rice crop during Stylosanthes establishment. Stylosanthes was broadcasted and seeded in line four weeks after rice sowing at rate of 4 gm-2. The effect of Stylosanthes establishment on tiller number, plant height, biomass, panicle length, spikelet fertility, 1000 seed weight and rice grain yield was evaluated. Number of plants, plant height, canopy width and biomass of Stylosanthes also were measured. No competition effect on rice-Stylosanthes intercropping treatment was observed when compared with rice monoculture. Number of Stylosanthes plants and its biomass was about 3 times greater when Stylosanthes was line-sown than broadcasted into the rice stand. Similarly, stylosanthes plants were taller and its canopy was wider when line-sown than when broadcasted. Further it needs to evaluate the effect of relay-seeding Staylosanthes residuals either as short–term or long-term fallow crops in improving rice productivity.

Intercropping systems; Slylosanthes guianensis, Upland rice cultivation

Most upland rice is produced in slash-and-burn agriculture systems as a dominant land use system in northern region of Laos. Currently, rapid population growth in combination with government policy on reducing areas under this land-use systems have resulted in increasing cropping intensity, which has increased weed problem, soil deterioration and consequently reduced yield of upland rice. The use legume cover during the time of crop still stand or after harvested of main crop for improved of land soil fertility before other routine cycle of crops into rice based cropping systems either as a component of rotation or through intercropping system (Roder, 2001, Roder and Maniphone, 1995). Stylosan-thes was used as cover crop have a positive effects in controlling weeds, improving soil fertility, improving crop yield, providing livestock feed and additional income through seed production, but the planted methods was for broadcasting than it growth was not very well by intercropping system under upland condition and mostly planted by rotation and at the station only (Carsky, Becker, et al., 2001, Tarawali, Manyong, et al., 1999). However, introdu-ced legume cover crops into upland rice through intercropping may also compete strongly with rice and adversely affect grain yield when it is not properly managed. Hence, there is a need to investigate different ways of establishing and growing the rice-legume association so that rice productivity is favored and to optimize survival of Stylosanthes plants and to achieve high Stylosanthes biomass accumulation after rice harvest period for subsequent rice crop season in the farmer’s field.
1 Results and Discussion
The analysis of variance (ANOVA) showed that there were no significant interactions between locations and location x treatments. There was statistical significant difference in some rice yield component (number of grain per panicle and spikelet fertility) and grin yield among treatment tested and also significant interaction between locations and treatments (Table 1).

Table 1 F-Probability values for each effected in the model of analysis of rice

Rice plants grown with line-sown stylosanthes was shorter and it was less rice straw dryness biomass than rice plants in the other treatments in an average from two locations (Table 3) and there was more rice straw dryness biomass at NAFReC, if compare to farmer’s field (Table 2).

Table 2 Interaction between locations and treatments of rice plants height, biomass, panicle length, % of spikelet fertility, 1000-seed weight and grain yield

Table 3 Rice plants, height, biomass, panicle length, % of spikelet fertility, 1000-seed weight and grain yield for treatments

Grain yield component were very important for increase of rice productivity as this result was shown it was high yield when intercropping between rice and stylosanthes was line sown and also significant difference between line and broadcast sowing as; more stylosanthes dryness biomass in line sown plot (Figure 1), but it was non significant between location and treatment interaction (Table 2) and only 4 percent of spikelet fertility in the plot of stylosanthes was line sown was provide higher grain yield of rice or yield advantage about 1074 kg/ha, it also highly significant difference by analysis of variance and standard error at 98.5% (Figure 2).

Figure 1 Interaction of rice grain yield and stylosanthes dryness biomass

Figure 2 Relationship between grain yield and percentage of spikelet

Interaction between of yield components (number of grain per panicle and spikelet fertility) were highly significant between rice stylosanthes line sown when compare to stylosanthes broadcast. Stylodanthes line sown intercropping system was effected to rice plant height was 7 to 10 cm different in the plot of line sown and broadcast of stylosanthes and also higher yield in short plant height plot when compare to longer plat (Figure 3).

Figure 3 Relationship between grain yield and plant height of each treatments

guinensis plant cans also competitions to rice plants height and it were decreased about 7 to 9 cm, but there was non significant difference. And stylosanthes plant height and canopy (22 cm wider than broadcast sown, these trends were observed in both sites where the trial was conducted) in the plot of stylosanthes line sown was highly significant difference from the plot of broadcasted into the rice (Figure 4, Table 5; Table 6).

Figure 4 Plant height competition between rice and stylosanthes intercropping

Table 4 F-Probability values for each effected in the model of analysis for Stylosanthes guianensis

Table 5 Interaction between locations and treatments of Stylosanthes guianensis plants height, biomass and canopy

Table 6 Effected of treatments of Stylosanthes guianensis plants height, biomass and canopy

biomass product was two times higher in broadcasted sown plants compared to line sown plant at NAFReC and fives time at farmer’s field in Selalek village, but all of them were non significant difference by statistic analysis. The height of stylosanthes were highly significant between location as at NAFReC was higher than in the farmer’s field and the treatment of rice and stylosanthes line sown at NAFReC was also significant difference from broadcasting sown (Figure 5). Highest biomass accumulation was observed at the time that the intercropped rice reached panicle initiation.

Figure 5 Relationship between height and dryness biomass of stylosanthes

There was highly significant difference competition effect of either stylosanthes sown in line after rice sowing on upland rice yield components and grain yield rice when they were seeded into rice stands at four weeks after rice sowing (1,075 kg/ha better than rice alone). This study were difference supported the findings of (Shelton and Humphreys, 1972, Shelton and Humphreys, 1975) found that broadcasting stylosanthes at 10, 31 or 60 days after sowing had no effect on rice yields in central Laos and northeast Thailand.

Rice with a stylosanthes intercrop performed better than rice alone, perhaps because stylosanthes leaf litter fall and die-off of root turnover improved soil fertility enough for rice growing in the vicinity of the stylosanthes plants to grow and develop better, and manifest this in improved grain yield.
There were trade-offs in the rice- stylosanthes intercropping system. When grown close together as in the rice+broadcast sown stylosanthes treatment, strong competition for light, soil moisture and soil mineral nutrients ensue. Competitive interactions outstrip benefits that stylosanthes may bestow on rice. Growing the crops in separ-ate rows minimize inter-specific competition and improved the grain yield of rice and biomass accumulation of stylosanthes per unit area.
2 Conclusions
Stylosanthes line sown after four weeks of rice sowing had highly effect on upland rice yield as 1.9 time or 1,075 kg/ha better than rice alone. But the broadcasting of stylosanthes establishment had no difference with rice alone. There was also optimum plants dryness biomass or accumulation during rice growth performance of stylosanthes by line sowing by three times or 2,221 kg/ha better than broadcasting. Further it needs to evaluate the effect of relay-seeding stylosanthes residuals either as short-term or long-term fallow crops in suppressing weeds, weed shift and improving soil fertility.
3 Materials and Methods
3.1 Study areas
The trial was conducted during the wet season in 2008 at Northern Agricul-ture and Forestry Research Center (NAFReC) and at farmer’s field in Ban Silalek (SL), Luang Prabang, Lao PDR.
3.2 Methods
The trial consisted of the following treatments:
(1) Rice only
(2)     Rice + Line sown stylosanthes guinensis (rice Stylo-L) (stylosanthes was sown in rows by 50 cm apart within rice stand, four weeks after rice was sown)
(3) Rice + Broadcast (rice Stylo-B) sown stylosanthes guinensis
The trial was laid out in a randomized complete block design with three replicates in each site. Individual plot size was 8 m x 10 m (80 m2). Laboun, a traditional upland rice cultivar, was sown at a spacing of 25 x 25 cm by placing about 8 seeds into 3-5 cm deep holes made a dibble bamboo stick on late May 2008 at NAFReC and early June at farmer’s field, and harvested on late September at NAFReC and Mid October at Farmer’s field. stylosanthes seeds were dipped in boiling water prior to seeding to break dormancy and immediately seeded at four weeks after rice sowing. stylosanthes was broadcasted into rice crop at the rate of 4 g m2. Weeding practice and timing was similar with those of farmers.
3.3 data collection
At rice tiller stage, panicle initiation (PI) and harvesting time, rice and stylosanthes plant height and plant number were measured from 15 random plants per plot, while destructive plant biomass were measured from a total 3 m2 area by 3 random of each 1 m2 samplings per plot. At maturity, panicle length, spikelet fertility (SPF) and 1000 seed weight of rice were measured from15 random plants per plot, rice grain yield from a 3 m2 area, while stylosanthes cover was recorded in a 3 m2 area in each plot.
Thank you to the financial support of Challenge Program on Water and Food for the researcher provided through Rice Landscape Management for Raising Water Productivity, Conserving Resources, and Improving Livelihoods Basins is also gratefully acknowledged.
Thank you to the Northern Agriculture and Forestry Research Center for granting any facilitate for laid out of these trials.
Carsky R.J., M. Becker and S. Hauser, 2001, Mucuna cover crop fallow systems: potential and limitations. Sustaining soil fertility in West Africa: 111-135
Roder W., 2001, Slash-and-burn rice systems in the hills of northern Lao PDR: description, challenges, and opportunitiesInt. Rice Res. Inst
Roder W., and S. Maniphone, 1995, Forage legume establishment in rice slash-and-burn systems. Tropical Grasslands 29: 81-81
Shelton H., and L. Humphreys, 1972, Pasture establishment in upland rice crops at Na Pheng, Central Laos. Tropical Grasslands 6: 223-228
Shelton H., and L. Humphreys, 1975, Undersowing rice (Oryza sativa) with Stylosanthes guyanensis. II. Delayed sowing time and crop variety. Experimental Agriculture, 11: 97-101

Tarawali G., V. Manyong, R. Carsky, P. Vissoh, P. Osei-Bonsu, and M. Galiba., 1999, Adoption of improved fallows in West Africa: lessons from mucuna and stylo case studies. Agroforestry systems 47: 93-122

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