Presenters: Jia-guo Zheng, Xin-lu Jiang, and Zhong-zhi Chi, Sichuan Academy of Agricultural Sciences Presented at the Workshop on the System of Rice Intensification, Exchanging Experience in China, the Democratic People's Republic of Korea and Internationally., held in Hangzhou, China, February 28-March 2, 2010 (Organized and hosted by the China National Rice Research Institute (CNRRI) with support from The Asia Foundation)

1. Modified SRI and super-high yield of hybrid rice in Sichuan Basin Jia-guoZheng,Xin-lu Jiang, and Zhong-zhi Chi Sichuan Academy of Agricultural Sciences

2. Introduction To assure food security in the rice-consuming countries of the world in 2030, farmers will have to produce 50% more rice than now with improved quality to meet consumers’ demand. The task of making further gains in production is more difficult when rice yields are already at a high level.

3. SRI, developed in Madagascar and synthesized in the early 1980s, offers opportunities to researchers and farmers to expand their understanding and accomplishment of the potential yield of rice varieties.

4. Why SRI can make advances in the rice yield? The methodology makes 3 main changes: Transplant younger seedlings, preferably 8-15 days old; Plant the seedlings singly, rather than in clumps of 3-6 plants, and with wider spacing; and Keep the paddy soil moist but not continuously saturated during the plants' vegetative growth phase. To achieve super high yield, rice researchers in China began evaluating and introducing SRI from 2000.

5. SRI is ideas, not a technology ---- Prof. Norman

6. Materials and methods for evaluation Experiment 1: Compared the original SRI methods (15 d seedlings, 40×40cm, single seedlings) with local techniques (CK) (50 d seedlings, 30×15cm, 1 seedling with 6 tillers). Experiment 2: Transplant rice seedlings at different densities, i.e., 40×40cm, 40×45cm, 45×45cm, 45×50cm, 50×50cm, and 55×55cm.

7. Experiment 3:Transplant with different planting patterns, i.e., CK = 50 d seedlings, 30×15cm, 1 seedling with 6 tillers SRI = 15 d seedling, 40×40cm, single seedling S+3 (square with 3 seedlings) =15 d seedling, 40×40cm, 3 seedlings per hill S+T (square with triangle) =15 d seedlings, 40×40cm, transplanting 3 seedlings separated at 7 cm, making a triangle in each hill O+T (oblong with triangle) =15 d seedlings, 40×45cm, transplanting 3 seedlings per hill separated by 7 cm each, making a triangle in each hill Experiment 4:Evaluate the suitability of different super-hybrid rice varieties for use with SRI or conventional cultivation methods.

8. Field demonstrations have been undertaken with modified SRI methods in a large scale at different experiment sites. Extension has been guided by the provincial agricultural extension center.

9. Farmer practice 30cm 15cm

11. Original SRI 40cm 40cm

12. ModifiedSRI: oblong with triangle 40cm 7cm 35cm

13. Results and discussion

14. SRI is a promising way to increase rice yield The average grain yield in Sichuan Province from hybrid rice with farmers’ practice has resulted in yields of about 8.5 t/ha. When SRI methods were first introduced, rice yield was increased by 20% Then with modified methods (oblong and triangle), the increase was still higher, at about 55%.

15. Table 1. Yield response to different planting patterns in rice

16. SRI promotes more vigorous growth of the rice plant With SRI methods, leaf blades become bigger, especially the functional leaves (Table 2). Plant height and culm length become longer. The stem diameter of the 4th internode (from the top) was 0.49 cm for SRI, 12% more than for CK. Hence it was documented that SRI management results in a very strong stem. Leaf area index (LAI) was also much higher for SRI methods than CK.

17. Table 2. Leaf blade size (cm) in response to SRI

18. 6th 5th 4th 3rd 2nd 1st Panicle Culm length SRI 2.63 7.57 11.73 14.47 22.47 45.4 25.64 137.79 CK 1.5 4.87 8.07 12.03 21.07 41.77 25.17 118.98 % 75.33 55.44 45.35 20.28 6.64 8.69 1.86 15.81 Internode length and culm length (cm)

19. Root system Stem

21. SRI gives high output with fewer inputs, but requires more manual work. SRI plants showed fewer insect and disease problems, and seed requirements were reduced by 50-90%. There was saving of water, by as much as 30%, with high WUE . However, SRI requires good and careful land leveling to facilitate good water control and minimal applications of water. Also, more time is needed for weed control because flooding is not used to suppress weeds.

22. Limiting factors for adoption When the number of foundation plants is less, this appears not suitable in an ecosystem with the low solar radiation of Sichuan. Single plants in a square pattern with wide spacing do not produce sufficient panicles per unit area. Consequently, yield potential is limited. Farmers want to maximize the number of panicles/m2, not panicles/hill. The oblong and triangular planting method appeared to be a valuable adaptation of SRI, increasing plant density by 50% while maintaining good exposure of individual plants to the sun and air.

23. It is hard to transplant young seedlings at 2-leaf age in multiple cropping system. Traditionally older-aged seedlings (about 7-leaf) are transplanted into the paddy fields after wheat harvest. If very young rice seedlings are used, the sowing date has to be postponed, which leads some unexpected results such as late maturity, less yield, and difficulties in field management.

24. Organic fertilizers are often in short supply. Because of the popularity of reduced or zero-tillage, local livestock populations are now decreasing in the rural areas. Hence, farmers now cannot get enough manure for organic fertilization. There is not a tradition of preparing compost from plant vegetative material.

25. Management measures such as manual weeding and keeping the soil moist are more complex than present practices, requiring more labor with SRI.

26. Improved SRI methods in Sichuan

27. Using tray nursery to raise seedlings The seedling nursery is managed under upland conditions, using plastic trays. Seedlings are removed carefully from the nursery and are transported to the paddy field, gently transplanted into the field within 15-30 minutes. This careful handling avoids having a long recovery time after transplanting, and leaf age can be extended to 3.5-4.5.

30. Transplanting density Best trans-planting density is seen to be 40-45 x45-50 cm.

31. Oblong with triangle transplanting pattern. Transplanting of 3 separated seedlings per hill in a triangular pattern produces more panicles/m2 and greater panicle size, giving more 'edge effect' throughout the growth period.

33. Younger seedlings are better

34. Application of herbicide when needed. Because of the wide space between plants and more fertile soil, there are more weeds with SRI than with conventional cultivation, especially in zero-tillage fields. But by combining herbicides and mulching measures, weeds can be reduced.

35. Adding chemical fertilizers to promote plant growth. The effect of organic fertilizer is slower than chemical fertilizer. Hence, chemical fertilizer is used to promote tillering and get more panicles during the productive tillering stage.

36. Inhibiting tillering after productive tillering stage. The tillering ability of rice plants is very strong, and the panicle-to-tiller ratio is often less than 50% in SRI. Mid-season drainage is thus recommended for SRI fields to inhibit excessive tillering.

37. Making shallow furrows before transplanting in zero-till fields. This is appropriate for the alternate wetting and drying (AWD) method, an effective and easy method for SRI water management. Shallow furrows help to implement AWD, maintaining aerated soil surfaces while some water is maintained or alternated in the furrows and moistens the root zone.

38. Making shallow furrows

39. Super-hybrid rice and the suitability to different cultivation systems

40. Based on the experience with high yield breeding in China and new plant type breeding in IRRI, a research project on breeding of super rice has been established since 1996. The project defined ‘super rice’ as a varietal type -- combining the harmonious plant type with heterosis to achieve super high yield, good eating quality, and multiple resistance to diseases and pests. Super-rice varieties released in China since 2005 now total 138 varieties. 11 super-hybrid rice varieties were collected for use in 2007-2008 trials, using both SRI practice and farmer practice to analyze the suitability of these varieties.

41. The SRI evaluations were done with random block design, each block = 150 m2. Plant spacing was 35×40 cm in triangle pattern with 3 seedlings in each hill. Total N was 195 kg/ha; P2O5 80 kg/ha; K2O 150 kg/ha. N was applied as urea, 50% basal, 30% at tillering stage, and 20% at panicle initiation. AWD was used throughout the crop cycle, with shallow flooding before active tillering and during panicle initiation (PI).

42. Farmer practice was evaluated also with random plot design and 3 replications. The size of each plot = 13.5 m2. Seed was sown on a plastic sheet on 5 April, and seedlings were transplanted on 15 May. Plant spacing was 26.67×16.67cm. Each hill was transplanted with 1 seedling (more than 5 tillers). Total N was 150 kg/ha, P2O5 50 kg/ha, K2O 112.5 kg/ha. N was applied as urea; 70% as basal, and 30% was used in tillering stage.

44. Super-hybrid rice showed, on average, 6.88% more yield potential (Shanyou63 606.53 kg/ha over the CK variety). Yield with SRI methods and Super-Hybrid Rice varieties (SHRs) was 10.29% higher (900.91 kg/ha) and with FP, 3.51% higher (312.15 kg/ha). SRI methods brought out potential of SHRs better than FP. General speaking, SHR has very good yield potential compared to the CK; but SHR varieties did not always perform better than the CK. SHR yield was lower than CK yield for three varieties with SRI management, and for two varieties gave lower results when cultivated with FP (Table 3)

45. SRI practice increased SHR yield on average by 4.93% (453.75 kg/ha). With 8 SHR varieties, SRI methods gave higher yield than FP (by an average increase of 959.6 kg/ha), whereas with 5 SHR varieties, FP gave higher yield (713.6 kg/ha average). Some varieties performed considerably better than others. Chuanxiang 9838 and II Youhang 1 showed a yield potential of 11 t/ha with SRI and 9 t/ha with FP. Some varieties, such as Liangyou-Peijiu, performed well with SRI, but gave poor output with FP.

46. 11 SHR varieties can be classified SRI-appropriate types: 4 varieties (Chuanxiang 9838, Zhongzheyou 1, II youhang 1, and Liangyou-Peijiu). These are suitably cultivated with young seedling age (less than 4.5 leaf age), wide spacing (7.5 hills/m2 or 22.5 seedlings/ m2), and high fertilizer application. They heave excellent tillering ability, with the last 3 leaves quite erect, and are strongly resistant to lodging. Farmer practice-appropriate types: 4 varieties (Nei 2 you 6, Zhunliangyou 527, II you 7, and II you 602) can be transplanted better at an older seedling age (more than 6-leaf age, 1 seedling with 6 tillers), with high density (30×15cm), and medium fertilizer applications. Neutral types: 3 varieties (D you 527, B you 827, and II you 084). These can give good yield both with SRI and FP management.

47. SRI extension in Sichuan

48. SRI was become the province’s preferred technique from 2005, and now it is considered as a principle technique for “rice high yield creation” in Sichuan Province. The application area is expanding rapidly, and the provincial yield record for rice production is being broken year after year (Table 4). SRI has been applied for 6 years in Guanhan City since 2003. Its rice grain yield reached 12.8 t/ha in 2008, certified by the Provincial Department of Agriculture and national experts. This is a new record of super-high yield in Sichuan ecosystem.

50. Economic returns to different patterns, 2005

51. Yield components for record harvest in Guanghan city (2008) Panicles/m2 228 Grains/panicle 191 Seed set rate 85.5% 1000 grain weight 29.5 Certified yield 12.8 t/ha Harvested area 743.4 m2

54. Conclusions

56. SRI is a new technique for rice culture being introduced in many areas across the world, but the techniques used in Madagascar are not all suitable for Sichuan. A modified version of SRI suited to the Sichuan agro-ecosystem can increase rice yield significantly in this province and maybe elsewhere. The modifications include: changes in transplanting density, leaf age, planting pattern, and field management. SRI is not a fixed technology but rather a set of ideas for creating a more beneficial growing environment for rice plants. As such, there should be continuing variations and evaluations by researchers and also by farmers to further modify and improve this system.

57. THANKS 谢 谢