1004 Modified SRI and super-high yield of hybrid rice in Sichuan Basin

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

Introduction,[object Object],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. ,[object Object],The task of making further gains in production is more difficult when rice yields are already at a high level.,[object Object]

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. ,[object Object]

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

SRI is ideas, not a technology,[object Object], ---- Prof. Norman,[object Object]

Materials and methods for evaluation ,[object Object],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). ,[object Object],Experiment 2: Transplant rice seedlings at different densities, i.e., 40×40cm, 40×45cm, 45×45cm, 45×50cm, 50×50cm, and 55×55cm. ,[object Object]

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

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

Farmer practice ,[object Object],30cm,[object Object],15cm,[object Object]

1004 Modified SRI and super-high yield of hybrid rice in Sichuan Basin

Original SRI ,[object Object],40cm,[object Object],40cm,[object Object]

ModifiedSRI: oblong with triangle ,[object Object],40cm,[object Object],7cm,[object Object],35cm,[object Object]

Results and discussion,[object Object]

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

Table 1. Yield response to different planting patterns in rice,[object Object]

SRI promotes more vigorous growth of the rice plant,[object Object],With SRI methods, leaf blades become bigger, especially the functional leaves (Table 2).,[object Object],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.,[object Object],Leaf area index (LAI) was also much higher for SRI methods than CK.,[object Object]

Table 2. Leaf blade size (cm) in response to SRI,[object Object]

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

Root ,[object Object],system,[object Object],Stem,[object Object]

SRI gives high output with fewer inputs, but requires more manual work.,[object Object],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 . ,[object Object],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.,[object Object]

Limiting factors for adoption,[object Object],When the number of foundation plants is less, this appears not suitable in an ecosystem with the low solar radiation of Sichuan. ,[object Object],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. ,[object Object],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. ,[object Object]

It is hard to transplant young seedlings at 2-leaf age in multiple cropping system.,[object Object],Traditionally older-aged seedlings (about 7-leaf) are transplanted into the paddy fields after wheat harvest. ,[object Object],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.,[object Object]

Organic fertilizers are often in short supply.,[object Object],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. ,[object Object],There is not a tradition of preparing compost from plant vegetative material. ,[object Object]

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

Improved SRI methods in Sichuan,[object Object]

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

Transplanting density,[object Object],Best trans-planting density is seen to be 40-45 x45-50 cm.,[object Object]

Oblong with triangle transplanting pattern.,[object Object],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.,[object Object]

Younger seedlings are better,[object Object]

Application of herbicide when needed.,[object Object],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. ,[object Object],But by combining herbicides and mulching measures, weeds can be reduced. ,[object Object]

Adding chemical fertilizers to promote plant growth.,[object Object],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.,[object Object]

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

Making shallow furrows before transplanting in zero-till fields.,[object Object],This is appropriate for the alternate wetting and drying (AWD) method, an effective and easy method for SRI water management. ,[object Object],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. ,[object Object]

Making shallow furrows,[object Object]

Super-hybrid rice and the suitability to different cultivation systems,[object Object]

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. ,[object Object],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.,[object Object],Super-rice varieties released in China since 2005 now total 138 varieties.,[object Object],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. ,[object Object]

The SRI evaluations were done with random block design, each block = 150 m2. ,[object Object],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. ,[object Object],AWD was used throughout the crop cycle, with shallow flooding before active tillering and during panicle initiation (PI).,[object Object]

Farmer practice was evaluated also with random plot design and 3 replications. The size of each plot = 13.5 m2. ,[object Object],Seed was sown on a plastic sheet on 5 April, and seedlings were transplanted on 15 May. ,[object Object],Plant spacing was 26.67×16.67cm. Each hill was transplanted with 1 seedling (more than 5 tillers). ,[object Object],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. ,[object Object]

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. ,[object Object],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) ,[object Object]

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). ,[object Object],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. ,[object Object]

11 SHR varieties can be classified,[object Object],SRI-appropriate types:,[object Object],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.,[object Object],Farmer practice-appropriate types:,[object Object],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.,[object Object],Neutral types:,[object Object],3 varieties (D you 527, B you 827, and II you 084). These can give good yield both with SRI and FP management.,[object Object]

SRI extension in Sichuan,[object Object]

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).,[object Object],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. ,[object Object]

Economic returns to different patterns, 2005,[object Object]

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

1004 Modified SRI and super-high yield of hybrid rice in Sichuan Basin

1004 Modified SRI and super-high yield of hybrid rice in Sichuan Basin

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1004 Modified SRI and super-high yield of hybrid rice in Sichuan Basin