Poster presentation at the 4th International Rice Congress Authors: Nurul Hidayati, Triadiati, and Iswandi Anas Title: Physiological and morphological changes in rice plants under SRI Venue: Bangkok International Trade and Exhibition Centre (BITEC), Bangkok, Thailand Date: October 28-31, 2014

1. Physiological and Morphological Changes in Rice Plants under System of Rice Intensification (SRI)
Management and Its Effects on Increasing Yield
Nurul Hidayati1, Triadiati2*, Iswandi Anas3
1Plant Biology Study Program, Graduate School, Bogor Agricultural University (IPB), Bogor, Indonesia
2 Department of Biology, Faculty Mathematics and Natural Sciences, Bogor Agricultural University (IPB), Bogor, Indonesia
3 Soil Biotechnology Division, Faculty of Agriculture, Bogor Agricultural University (IPB), Bogor, Indonesia
*Corresponding author: adiatiipb@gmail.com
ABSTRACT
System of Rice Intensification (SRI) has been reported by many authors to increase rice yield significantly. However, there have been few reports on the impacts of SRI management on rice physiology and morphology. This research observed chang- es in rice physiological and morphological parameters under SRI cultivation method compared to conventional rice cultivation methods as well as their effects on rice yield improvement. The research used Randomized Block Design (RBD) consisting two rice cultivation methods, namely SRI and conventional rice cultivation practice. In SRI cultivation method, transplanting was done at a seedling age of 10 days, with planting distance of 25 cm x 25 cm, one seedling per hill, with the soil just kept moist. In conventional rice cultivation, transplanting was done at a seedling age of 25 days, with planting distance of 20 cm x 20 cm, three seedlings per hill, with continuously flooded soil condition. The fertilization for both methods was the same, i.e., 125 kg Urea ha-1, 100 kg SP-36 ha-1, 50 kg KCl ha-1 and 2.5 t ha-1 organic fertilizer. The results showed that rice plants grown with SRI cultivation methods had significantly higher vegetative parameters (total tillers number, productive tiller num- ber, leaf number, leaf area, width of canopy at 20 cm above soil surface) compared to those raised with conventional rice cultivation methods. The rice plants’ photosynthesis activity, chlorophyll a, chlorophyll b, total chlorophyll content, and nutrient uptake (N and P) were significantly higher with SRI cultivation methods compared to conventional rice cultivation method. But no difference in transpiration and leaf temperature was found. Grain yield under SRI cultivation methods was significantly higher (ca. 24%) than conventional rice cultivation method.
Key words: System of Rice Intensification (SRI), conventional rice cultivation method, rice physiology, rice morphology
INTRODUCTION
A new method of rice cultivation practice has been developed, System of Rice Intensification (SRI), with productivity increases validated in more than 50 countries, including major rice producers in the world such as India, China, Vietnam, Indonesia, Cambodia and Philippines (Katambara et al. 2013). Four critical components in the implementation of SRI method, namely planting of young seedlings (8-12 days), planting of single seedlings (one seedling per hill), wide spacing (25 cm x 25 cm), and non-flooded soil conditions, plus active soil aeration and enhancement of soil organic matter (Barison & Uphoff 2010).
The SRI methodology has been shown to increase the growth and grain production of rice, even though the number of seeds and the amount of water used are much less than conventional methods. However, little is known about the influence of SRI methods on the rice physiology that leads to the improvement in growth and yield of rice than the conventional methods. Therefore, information regarding the effects of SRI cultivation on rice physiology is needed. The aim of this research was to measure physiological parameters of rice under cultivation with SRI methods and conventional methods, and their influences on the level of rice production.
CONCLUSIONS
The rate of photosynthesis, the amount of chlorophyll a, chlorophyll b, total chlorophyll content, and the uptake of nitro- gen and phosphorus in rice cultivation under the SRI method were higher than in conventional methods of rice cultivation. However, there were no difference in transpiration and leaf temperature were observed in both rice cultivation methods. Physiological changes of rice affected the vegetative and generative growth of the rice plants. Vegetative growth of rice plants cultivated under SRI method, i.e., plant height, tiller number, leaf number, leaf area, shoot dry weight, width of the canopy at 20 cm above soil surface, number of productive tillers per hill, and number of productive tillers per m2 were high- er than in conventional rice cultivation method. Generative growth of rice also increased with SRI methods, i.e., panicle length, number of filled grains per hill, total number of grains per hill, the grain dry weight per hill, the grain dry weight per m2 , the grain dry weight per m2 (grain yield), but the percentage of empty grains was decreased.
ACKNOWLEDGEMENT
This study was funded by Lembaga Pengelola Dana Pendidikan (LPDP). We are grateful to staff of the Plant Physiology Laboratory, the Department of Biology, the Soil Biotechnology Laboratory, the Department of Soil Science and Land Re- sources, and the Bogor Agricultural University (IPB) for their assistance, and to staff of Balai Penelitian Tanaman Rempah dan Obat (BALITTRO) who helped in measuring photosynthesis.
MATERIAL AND METHODS
This research was conducted in Sindang Barang Jero, West Java, and Laboratory of Plant Physiology, Department of Biology, Faculty of Mathematics and Natural Sciences, Bogor Agricultural University, from October 2012 to September 2013. The materials used were Ciherang variety of rice, Urea-based fertilizer (44.7% N), SP-36 fertilizer (38.9% P2O5), KCl fertilizer (59.9% K2O), and compost enriched with plant growth-promoting rhizobacteria (PGPR) (Bacillus sp., Pseu- domonas sp., Azospirillum sp., and Azotobacter sp.), collection of the Laboratory of Microbiology, Department of Biology, Faculty of Mathematics and Natural Sciences, Bogor Agricultural University. Measurement of photosynthesis, transpira- tion, and leaf temperature was done by using the LI-COR Biosciences (Nebraska, USA), and chlorophyll content was measured using spectrophotometer type Spectro GenesysTM 20 (Massachusetts, USA).
The research was designed according to the randomized block design (RBD), in which the method of rice cultiva- tion consisted of two treatments: the Conventional rice cultivation method and System of Rice Intensification (SRI) meth- od. Each treatment was replicated five times. The size of the experimental plots was 4 m x 5 m (20 m2).
Table 1. The comparison between conventional rice cultivation method and SRI method
REFERENCES
Barison J, Uphoff N. 2010. Rice yield and its relation to root growth and nutrient-use efficiency under SRI and convention- al cultivation: An evaluation in Madagascar. Paddy and Water Environment 9: 65–78.
Katambara Z, Kahimba FC, Mahoo HF, Mbungu WB, Mhenga F, Reuben P, Maugo M,Nyarubamba A. 2013. Adopting the system of rice intensification (SRI) in Tanzania: A review. Agricultural Science 4: 369-375.
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Effects of Cultivation Methods on Rice Physiological Parameters
Figure 6. Rice physiology in 4 phases of growth (V: vegetative; F: flowering; G: grain filling; M: mature stage). (a) photo- synthesis, (b) transpiration, (c) leaf tem- perature. Conventional SRI
Figure 7. Chlorophyll content in 4 phases of growth (V: vegetative; F: flowering; G: grain filling; M: mature stage). (a) chlorophyll a, (b) chloro- phyll b, (c) total chlorophyll.
Conventional SRI
Figure 8. Nitrogen and Phospho- rus uptake at 70 DAS. (a) leaf N-content, (b) leaf N-uptake, (c) leaf P-content, (d) leaf P-uptake. Kon: Conventional; SRI: Sys- tem of Rice Intensification.
a b c d
Effects of Cultivation Methods on the Generative Growth of Rice
a b c d
e f g h
RESULTS
Effect of Cultivation Methods on Vegetative Phase
Figure 1. Vegetative growth of rice. a) plant height, b) tiller number, c) leaf num- ber, d) leaf area.
: Conventional
: SRI
Figure 2.Shoot dry weight at 70 and 110 days after sowing. Kon: Conventional; SRI: System of Rice Intensification.
Figure 3. Width of the canopy at 20 cm above soil surface at 70 days after sowing. Kon: Conventional; SRI: System of Rice Intensification.
Figure 4. Number of productive tillers. Number of productive tillers per hill (a), and number of productive tillers m-2 (b). Kon: Conventional; SRI: System of Rice Intensification.
a b
a b c d
a b c
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Figure 9. Generative growth of rice. (a) panicle length, (b) number of filled grains, (c) number of total grains, (d) percent- age of empty grains, (e) grain dry weight, (f) weight of 1,000 grains, (g) grain dry weight at harvest, (h) grain dry weight m-2. Kon: Conventional; SRI: System of Rice Intensification.
Planting
Conventional
System of Rice Intensification (SRI)
Seedling age
25 days old after sowing
10 days old after sowing
Spacing
20 cm x 20 cm
25 cm x 25 cm
Number of seedlings per hill
3 seedlings per hill
1 seedling per hill
Number of hills per m2
25 hills per m2
16 hills per m2
Number of plants per m2
75 plants per m2
16 plants per m2
Irrigation water
Continuously flooding
Soil was kept moist
Conventional
System of Rice Intensification
Figure 5. Performance of rice plant growth under conventional rice cultivation method (left) and SRI (right) at 70 days af- ter sowing.