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1808 - Effects of SRI in Limiting Negative Impacts of Adverse Weather Conditions

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Author: Hoang Van Phu
Title: Effects of SRI in Limiting Negative Impacts of Adverse Weather Conditions
Presented at: The 5th International Rice Congress (SRI research side event)
Venue: Sands Expo and Convention Centre, Singapore
Date: October 16, 2018

Published in: Environment
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1808 - Effects of SRI in Limiting Negative Impacts of Adverse Weather Conditions

  1. 1. Effects of SRI in limiting the negative impacts of adverse weather conditions Hoang Van Phu – Coordinator of Vietnam SRI Network and Professor, Thai Nguyen University
  2. 2. What are the negative impacts of adverse weather conditions? • Rice is affected by COLD TEMPERATURES • Rice in rainfed and terraced areas can be badly affected by DROUGHT • Rice can get lodged due to STRONG WINDS with typhoons and heavy rain • Rice gets damaged by FLOODING
  3. 3. SRI vs. Cold What happened in the case being reported here? • Temperatures were lower than 10oC and lasted for a long time (3 weeks to 1 month) What was the result for crop with conventional management? • Rice seedlings died, or • Poor tillering if they survived
  4. 4. Comparison in Xuan Phuong (2010) CONVENTIONAL (n=32) SRI (n=48) Seedlings in nursery Weak, some died Good growth Rice after transplanting Folded and dry leaves, some rice plants died Good recovery Tillering Very poor (11.2 tillers) Good (19.6 tillers) Panicles/culm 7.4 15.5 No. of grains/panicle 176 195 % of filled grains 158 189 Yield (tons/ha) 5.4 7.2
  5. 5. Conventional SRI
  6. 6. Low density of sowing for seedlings in the nursery  good growth
  7. 7. Explanations for SRI Effects CONVENTIONAL (n=32) SRI (n=48) Sowing density High ( 3 kg / 10m2 ) Low ( 0.3 kg / 10m2 ) Seedling quality Roots are on the surface, poor seedlings or they die Roots are in deeper layer, get stronger seedlings Way of transplanting Uprooted seedlings Taking up seedlings carefully with soil around roots Consequence Roots are damaged, poor functioning in water uptake, poor recovery, some plants die Roots are strong and protected, no damage and suffering from cold, good water and nutrients uptake, no plants die Poor growth and tillering Good tillering Lower number of panicles and filled grains, low yield More panicles and filled grains, got very good yield
  8. 8. What happened in this case: • Drought lasted long time during transplanting and heading time – with conventional practices @ Transplanting time: poor seedlings, no water, late transplanting, old seedlings, poor tillering @ Heading time: Poor heading, more unfilled grains • Yield was seriously reduced SRIvs. Drought
  9. 9. Comparison in Hung Nguyen (2015) CONVENTIONAL (n=5) SRI (n=5) % of root weight at harvesting time: In volume of soil from surface to 5 cm deep 60.7 49.2 In volume of soil from 6 cm to 25 cm deep 39.3 50.8 Tillers 7.2 14.8 Panicles/culm 6.5 12.4 Number of grains/panicle 103 142 % of filled grains 42.7 68.7 Yield (tons/ha) 3.3 4.9
  10. 10. Explanations for SRI Effects Practice CONVENTIONAL (n=62) SRI (n=43) Seedlings Poor Strong Transplanting density Roots are more on surface, poorer seedlings Roots reach deeper layer, stronger seedlings Water mgmt Keep standing water Alternating wet and dry Consequence Roots are mainly distributed in surface layer (85%) Roots were strong and deep, therefore able to resist drought during dry period Poor heading, unfilled grains Good heading, more filled grains Loss of yield Maintain yield
  11. 11. What happened in this case? •Typhoon and heavy rain with strong winds during the milk stage of grain development •Plants lodged •Loss of yield SRI helps rice farmers to resist Lodging
  12. 12. Comparisons in Cho Don, Backan CONVENTIONAL (n=88) SRI (n=68) Roots Many, but small (0.61 mm) and on surface Big and strong (0.78 mm), deep Plant Weak Strong Diameter of 3rd node Small (5.34 mm) Bigger (5.78 mm) Thickness of wall Thin (0.56 mm ) Thick (0.63 mm) Leaf sheath Yellow, loosened or dead Strong, tight, support # of grains/panicle 143.8 176.7 % of filled grains 27 89 Yield (tons/ha) 2.1 6.8
  13. 13. Explanations for Effects CONVENTIONAL (n=32) SRI (n=48) Seedlings Old Young Transplanting density High Optimally low, roots are deeper, strong seedlings Water mgmt Keep standing water Alternate wet and dry Consequence Roots small, weak, most in surface; weak stems; dense population good for diseases and pests; yellow and loose sheath; more brown plant hopper and sheath blight Roots are anchors; strong stems supported by strong and tight sheath; less brown plant hoppers and sheath blight Results Lodging, spikelet sterility, serious loss of yield Strong stand, filled grains, high yield
  14. 14. What happened here? • In 2017, flooding in Dai Tu and Dinh Hoa, Thai Nguyen province during summer rice crop • High rainfall (3,700 mm); 3 times of big flooding, flooding over rice for 3-4 days • With flooding at the beginning of tillering, most rice plants under conventional practice died; in contrast, those with SRI practice recovered and tillered well • Near heading time: In conventional practice, panicles were affected, many unfilled grains, very low yield; in contrast, those plants under SRI practice recovered well (as a ratoon crop), giving good yield SRI vs. Flooding
  15. 15. Comparison CONVENTIONAL (n=53) SRI (n=42) No. of panicles/culm 7.9 25.6 (new) Panicles w/ filled grains 6.0 21.2 (new) Filled grains/panicle 12 103 Yield (tons/ha) 1.8 4.6 Results Plants died, or very few filled grains because panicles suffocated Panicles that were stuck in leaf sheath cannot have full heading, only grains out of leaf sheath can fill, others inside sheath die; but after that, rice plants recovered very fast with 2 or 3 new branches per stem appearing (like a ratoon). After 46 days, these branches became panicles with grain filling
  16. 16. Explanations for Effects CONVENTIONAL SRI Rice strength Dense planting, weak roots, stems, leaves Lower population  strong roots, stems and leaves Survival and recovery capacity Poor; only some parts of panicles have some filled grains, so little yield For ratoon crop, nutrients (carbohydrates) are available in stems, sheaths and leaves; these support good recovery. With survival instinct, dormant axillary buds in upper nodes grow fast (good C:N ratio), develop new panicles with filled grains. -- Although less grains per panicle, more panicles maintain good yield (Vergara B.S, F.S.S. Lopez, and J.S. Chauhan, 1988)
  17. 17. Conclusions •SRI is simple and effective • Simple: easy, suitable for small farmers • Effective: “less inputs  more outputs”, higher yield and more favorable cost – benefit efficiency •“Smart” approach • Can fit to farmer’s available resources and condition • Help farmers to become resilient to the stresses of climate change •“Smart” practices: • Pay attention to strength of seedlings  change the way of growing seedlings in the nursery • Change the concept/practice of transplanting  placing single seedlings at suitably sparse density • Change methods of water mgmt, from standing water to wet and dry • Pay attention to the life in the soil which supports root systems
  18. 18. Thank you very much for your attention! Hoang Van Phu Email: phuhv@tnu.edu.vn Tel: (84) 912141837

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