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Drought and heat stress in late sown wheat and mitigation strategies


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Effect of Drought and heat stress in late sown wheat and mitigation strategies in case of Nepal

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Drought and heat stress in late sown wheat and mitigation strategies

  1. 1. Welcome
  2. 2. RAMESH ACHARYA AGR-05M-2013 DEPARTMENT OF AGRONOMY AGRICULTURE AND FORESTRY UNIVERSITY A graduate Seminar On Drought and heat stress in late sown wheat and mitigation strategies
  3. 3. INTRODUCTION Wheat is the major cereal crop of world. 89 nations have 2.5 million wheat consumers worldwide (CIMMYT,2013) Wheat is grown on 215 million hectare of land each year which is equivalent to Greenland (CIMMYT,2013) Used for food 65% Used in animal feed 17% Used in industries including biofuel 12% others 6% 2013/14 Source: FAO statUse of wheat grain for 2013/14 Source: CIMMYT
  4. 4. Of the total cereal production area, wheat occupies 22.58% (MOAC,2014) Of the total cereal production, wheat occupies 20.13%. (MOAC,2014) 0 500000 1000000 1500000 2000000 2500000 3000000 3500000 2010/11 2011/12 2012/13 Total cereal area(Ha) Total wheat area(ha) 0 2000000 4000000 6000000 8000000 10000000 2010/11 2011/12 2012/13 Total cereal production (mt) Total wheat production (mt) o In Nepal, 84% of wheat area comes under Rice –wheat system (Timsina & Conner,2001) which is 0.6 Mha (Timsina et al.,2007) o There are 35 improved wheat cultivars, 40 landraces and 10 wild relatives of wheat in Nepal (Joshi et al., 2006) o The productivity of wheat in Nepal is 2.29 t/ha which is much less than average productivity of world (MOAC,2014)
  5. 5. Contd. Lack of irrigation Major yield limiting factors Late planting due to longer window period after rice harvest Use of late maturing rice varieties Lack of wise use of plant nutrients Abiotic stress Heat stress Drought stress Frost stress Biotic stress Plant diseases Insects
  6. 6. Results and Discussions Importance of sowing date  Early sowing provides longer period of maturation, earlier flowering and higher yield potential (Coventry et al.,??).  Wheat in Nepal is generally sown in November to late December and harvested in March/April (Joshi et al.,2006).  Timely planting of wheat is often delayed by tillage and yield potential is also reduced. This is due to rice crop vacating the field late (Hobbs et al.,2005; Gupta et al.,2010).  With delay in sowing time from 1st fortnight of November to 1st fortnight of December, a decline in yield at 32 kg/ha /day is reported (Tripati et al.,2005).  A yield loss of 1-1.5% for delay of each day after the optimum sowing date of Nov 15 in wheat crop is recorded (Hobbs et al.,2005).
  7. 7. Contd.. Effect of sowing date on grain yield of wheat Effect of sowing date on grain yield and biomass 0 5 10 15 20 25 30 35 Grain yield Biomass yield 7.56 32.6 5.49 26.6 Yieldint/ha Optimum sowing Late sowing 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 21st Nov 5th Dec 19th dec 2nd Jan 4.62 3.71 3.31 3.16 Yieldint/ha Date of sowing of wheat 2009/10 2010/11 Source: Aslani et al., 2011 , Iran
  8. 8. Contd.. Grain Yield of different varieties affected by sowing date, Rampur ,Chitwan Straw yield of different varieties affected by sowing date, Rampur , Chitwan 0 1 2 3 4 5 6 5-Nov 20-Nov 5-Dec 20-Dec Grain yield on different dates in t/hec yieldint/ha NL 297 BL 1443 0 1 2 3 4 5 6 7 8 9 5-Nov 20-Nov 5-Dec 20-Dec straw yield on Dates of sowing yieldint/ha Gautam NL 297 Source: Nabaraj Acharya, 2008
  9. 9. Effect of sowing time on grain filling rate, yield per panicle and plant height on five cultivars named Seri I- 84, Hartog, Bhrikuti, Gautam, Nl-2800 Normal sowing ( 22nd November) Late sowing ( 2nd January) Mean Plan0t height (cm) 69.25 57.58 Seed filling rate (mg/day) 0.71 0.75 Yield per panicle(gm) 1.37 0.908 Source: P.R.Timsina,2008
  10. 10. Effect of sowing on Days to Booting, Days to Heading, Flag leaf duration, Days to maturity and Grain filling duration assessed on 5 varieties on Rampur, Chitwan Normal sowing (22nd November) Late sowing (2nd January) Days to booting 57.73 51.79 Days to heading 68.86 63.00 Flag leaf duration 59.13 44.60 Days to maturity 122.40 103.26 Grain filling duration 53.56 39.53 Source: P.R.Timsina, 2009
  11. 11. Contd… How terminal moisture stress limits the yield?  Many Scientists and researchers have reported of this drop in grain and biomass yield is due to exposure of plant to terminal heat and drought stress.  Terminal stress is the moisture stress mainly during dry seasons on heavy soil, where plants are grown on stored moisture and matures on progressively depleting moisture profile(Ludlow & Muchow,1988).  Nirman et al., 2013 simulated and concluded that yields of rainfed wheat was lower (1.7 t/ha) due to water stress during the post anthesis phase resulting in early senescence during dry years.  And wheat in case of Nepal is sown after rice and it grows and survives on the residual soil moisture and late monsoon rain or winter rain (Nirman et al.,2013) which is only 20% of the annual rainfall (Malla, 2008).  As 0.8 tons of water is required to produce 1 kg of wheat grain (Wani GM,2011),Wheat production falls short of moisture.
  12. 12. How water affects the grain yield? Water Water lost Runoff Deep drainage Soil Evaporation Water stored in soil Water not extracted by crop Plant survival Water use efficiency Partitioning efficiency Water used by crop Dry matter production Fig: Schematic Diagram between water and grain yield Source: Ludlow & Muchow
  13. 13. Effect of terminal heat stress on yield Terminal heat stress is due to mean daily temp exceeding 17.50C in the coolest month in wheat growing region(Fischer & Byerlee, 1991).  Increase in temperature reduces crop duration, increase crop respiration rates, reduces crop yield , increased sterility that reduced the no. of grains formed, inhibit sucrose assimilation in grain, affect survival and distribution of pest populations (Hundal & Kaur,2007).Change in Temperature Decrease in yield Place of experiment Source 1-3°C in maximum temp 8-31% Nepal Pandey et al.,2007 1°C in mean temperature 5% Australia Tashiro & Wardlow, 1989 2°C in mean seasonal temperature 50% Australia Foster et al.,2011 Rise in night temperature 5.8% India Gupta et al.,2010
  14. 14. Contd..  Rane et al.,2002 reported that thirty million hectares of crop was affected by terminal heat stress in temperate growing regions.  In wheat, the grain filling duration continued to decrease at temperatures above 26.7 °C.  Similarly heat induced spikelet sterility and increased in the respiration losses from the crops during the grain filling also caused by rising temperatures (Timsina and Humphrey,2006).  Heat stress affects the grain set if occurred during flowering and terminal heat stress reduces number of grains, weight of grain and grain filling duration (Chenu et al.,; Wall et al., ;Aggrawal &Kalra,1994).  Wheat crop experiment conducted in open top chamber in NARC showed that decrease in the growth stage like spike initiation, heading, flowering, milking and physiological maturity by 14, 5, 9, 6 and 14 days respectively due to increase in temperature(Malla,2008).
  15. 15. How heat stress affects on wheat plant? Wheat organ Effect on wheat plant Spikes o Kernel abortion at supra-optimal temperature For photosynthetic canopy o Photo-inhibition due to excess light o Impaired metabolism Stems o Hydraulic resistance to high transpiration rate is likely to become rate limiting Roots o Limited capacity for water uptake to match evaporative demand at high vapor pressure deficit may cause stomatal closure Source: Cossani and Reynolds,2012
  16. 16. Reduction (%) in various wheat traits under drought and heat stress conditions Trait Drought stress Heat stress Plant height 11.6 6.5 Productive tillers 19.7 -31.1 Days to heading 6.2 10.1 Days to anthesis 3.8 10.1 Days to maturity 4.5 10.7 Grain filling duration 6.7 11.3 No of grains per spike 4.4 3.3 Grain weight per spike 3.7 16.8 Thousand grain weight -1.1 14.1 Grain yield 29.1 26.4 Source: Sarren et al., 2014
  17. 17. Mitigation strategies  Advancing in plant date No-till method A yield increase up to 41% is recorded by zero till plot over conventional tilled due to 24 days earlier in planting date(Hobbs & Gupta, 2003). Planting the wheat in advance using zero-till ,sowing of the varieties that can either adapt or escape terminal stress, using of crop residues./mulching, wise use of irrigation (irrigation scheduling) and plant nutrients (site specific nutrient management) are suggested as possible solutions for combating the terminal stress in wheat production (Jat et al.,2009). Use of early maturing rice varieties in rice-wheat cropping system.  Cultivar choices Use of varieties that can either tolerate heat, avoid heat or escape drought/heat. Early maturing varieties –Adoption of early maturing varieties showed 10% yield advantage over long duration varieties(Joshi et al.,2012).
  18. 18. Effect of conservation practices on crop yields, water saving and water productivity Cultivation Practices Location / Country Yield gain over conventional practices (kg/ha) Water saving over convention al practices (ha-cm) Increase in water productivit y (kg/m3 ) Source No till Karnal, India 140-400 2-4 0.10-0.21 Malik et al.,2005 No till Meerut, India 610 2.2 0.28 Gathala et al.,2010 No till with surface residue Karnal, India 500 6.1 0.24 Gathala et al.,2010 No till with surface residue Meerut, India 410 1.0 0.13 Jat et al.,2010 Source: Chauhan et al.,2012
  19. 19. Contd.. An experiment conducted at 14 sites of various countries , Nepal(1), India (6), Bangladesh (2), Pakistan (1)and Mexico(4), by CEISA as Heat trial- Early maturity trial during 2009-10 showed superiority (>10%) of 10% lines over local checks. Stay green varieties- As there is positive association between duration of photosynthetically active leaf area and grain yield, identification of molecular markers for stay green trait can further open doors to fight heat stress( Singh et al., 2012). Using varieties with higher water-use efficiency. Using varieties with heat tolerance traits as membrane thermostablity, stomatal conductance and heat shock proteins (Slafer & Whitechurch,2001).  Use of mulching-decreases evaporation and increases water availability  Irrigation management –wise use of irrigation by scheduling on critical stages  Balanced plant nutrition
  20. 20. Conclusion  Late planting of wheat is one of the major cause for exposure of wheat plants to terminal heat and drought stress.  Terminal stress of heat and drought affects on wheat phenology and all yield attributing traits resulting in significant drop in biomass and grain yield.  Use of better cultivation practice (Zero-tillage) with retention of crop residues/mulching, selection of early maturing varieties with better management practices and breeding works over identification of molecular markers for heat and drought tolerance is the future to solve the above mentioned stress.
  21. 21. Thank you for your patience