Effect of moisture stress timing and nitrogen on growth and yield of upland rice

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Effect of moisture stress timing and nitrogen on growth and yield of upland rice

  1. 1. Effects of Moisture Stress Timing and Nitrogen Levels on Growth and Yield of Upland Rice ALIBU Simon1 and MAMADOU Fofana2 1National Crops Resources Research Institute (NaCRRI), P. O Box 7084, Kampala, Uganda 2Africa Rice Centre (WARDA), 01 B.P. 2031, Cotonou, Benin
  2. 2. INTRODUCTIONMoisture stress and insufficient nitrogen are important factors thatsimultaneously limit growth and yield of upland riceThese two factors have repeatedly been studied but little is knownabout their interactive effects on growth and yield when thetiming of stress is varied.The main purpose of this study was to examine the interactiveeffects of nitrogen and water stress occurring at different growthstages of upland rice on phenology, grain yield, yield componentsand biomass productionKnowledge of this is important for planning interventions likesupplementary irrigation and fertilization in the context of Africawhere rainfall patterns are erratic and fertilizer unaffordable.
  3. 3. MATERIALS & METHODSExperimental Layout: 2 Factor RCBD with 2 Replications Replication 1 Replication 2Factors: 3 Nitrogen levels and 5 stress treatments + ControlN Levels: 30 kg N ha-1, 60 kg N ha-1 and 90 kg N ha-1 60% applied as basal and 40% as topdress
  4. 4. STRESS TREATMENTSSowing Maximum Tillering 10 DAH Active Tillering Early Vegetative 20 DAH 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Weeks Aft er Sowing Control treatment (S-6) watered with 30 mm wk-1 Soil moisture stress initiated at 11 days, 32 days and 53 days after sowing for S-1, S-2 and S-3 respectively
  5. 5. DATA COLLECTION Plant height, tiller number, yield & yield component measurements Leaf area and dry matter measurementsTiller numbers plant height measured weekly from vegetative toheading and at harvest.On last day of stress, 3 hills harvested per plot to measure drymatter accumulation. Dry weight taken after drying at 70o c for 72 h. FreshWeight - Dry Weight LRWC = X 100 Turgid- DryWeight
  6. 6. MONITORING SOIL MOISTURE A Calibration curve was used to transform moisture meter readings to true soil moisture values Moisture Meter Callibration Curve 70 Moisture Meter ReadingMoisture Meter 60 y = 0.6091x + 21.607 type HH2 R2 = 0.9464http://www.delta-http://www.delta-t.co.uk 50 40 30 20 0 20 40 60 80 True Value Due to large variation in single point M.C readings within each box, average of 10 readings taken/box
  7. 7. RESULTS AND DISCUSSION Changes in volumetric water content 50 50 50 Early Veg. Stage Active Till. Stage Max. Till. Stage 45 45 45 40 40 40 35 35 35Soil Water Content (%) 30 30 30 25 25 25 0 7 14 21 28 0 7 14 21 28 0 7 14 21 28 50 50 10 Days After Heading 20 Days After Heading 45 45 Volumetric soil water content 40 40 declined gradually from over 35 35 40% to less than 30% within 30 30 2 – 3 weeks 25 25 Changes in soil water status were 0 7 14 21 28 0 7 14 21 similar for all stress treatments Duration of Stress (Days) Control N-1 N-2 N-3
  8. 8. EARLY VEGETATIVE STAGE STRESS 100 89 87 88 80 77Control Stressed 71 71 Moisture stress had a LRWC % 60 small effect on LRWC 40 20 Nitrogen had negligible 0 S W S W S W effect on LRWC N-1 N-2 N-3 Stress effects mild S: Stressed, W: Well watered Stress effects (leaf rolling & tip drying) developed slowly and occurred at lower soil moisture status than in older plants probably due to limited water requirements of rice at this stage. Dry matter production reduced by 44% because moisture stress inhibited formation of new leaves. LAI reduced by 82%. Plant height was not significantly affected by moisture stress and Nitrogen
  9. 9. ACTIVE TILLERING STAGE STRESS 100 90 89 91 80 Moisture stress LRWC % 62 considerably reduced 60 51 50 40 LRWC 20 0 Nitrogen had a minor S W S W S W effect on LRWC N-1 N-2 N-3 S: Stressed, W: Well watered Stress effects severe Stress effects developed quickly due to aControl Stressed large demand for transpiration water 140 Dry matter production was reduced by 37% 120 T i l l e rs m-2 because moisture stress prevented tillering. 100 LAI reduced by 50%. 80 60 Tillering was reduced by moisture stress at 40 higher N levels. 30 60 90 -1 Nitogen Level (Kg Ha )
  10. 10. Control Stressed MAXIMUM TILLERING STAGE STRESS 100 91 90 87 80 Moisture stress had a large effect on LRWC LRWC % 60 57 50 48 40 20 Increased N supply 0 decreased LRWC in the S W S W S W stressed rice plants N-1 N-2 N-3 S: Stressed, W: Well watered Stress effects appeared almost immediately after the onset of stress A high degree of leaf senescence was observed – signifying severity of the stress. Dry matter and LAI were reduced by 49% and 58% accordingly
  11. 11. GROWTH AFTER STRESS Crop Growth Rate (CGR) 0.08 0.08 S1 S2 S3Crop growth rate (gg-1 Day -1) 0.07 0.07 S1 S2 S3 0.06 0.06 0.05 0.05 0.04 0.04 0.03 0.03 0.02 0.02 0.01 0.01 0.00 0.00 30 60 90 30 60 90 Nitrogen level (kg ha-1) -1 Nitrogen Level (kg ha ) Post stress crop growth rate was highest in S-1 and lowest in S-3 Raising N level to 60 kg ha-1 increased the CGR in S-1. Beyond 60 kg ha-1, CGR declined. N application reduced the CGR in S-2 and S-3 due to severity of soil moisture stress during active vegetative growth.
  12. 12. Tillering Rate 0.14 0.14 S1 S-1 Tillering rate (tiller tiller day )-1 0.12 0.12 S-2 S2 S-3-1 0.10 0.10 S3 0.08 0.08 0.06 0.06 0.04 0.04 0.02 0.02 0.00 0.00 30 60 90 30 60 90 -1 -1 Nitrogen level (Kg ha ) Nitrogen Level (kg ha ) Tillering rate was highest in S-1 and lower in S-2 and S-3 respectively. A high correlation (r = 0.946) found between tillering rate and CGR Raising N level to 60 kg ha-1 increased the tillering rate in S-1. Over 60 kg ha-1, the tillering rate declined. Low tillering rate in S-3 is because the maximum tiller number had already been attained at the onset of stress
  13. 13. Recovery After StressNitrogen application enhanced recovery in rice stressed at the early vegetative stage (S-1)
  14. 14. TIME TO HEADING S-3 S-2 S-1Control DAS 90 92 94 96 98 100 102 104 106 108 110 112 114 116 118 120 122 124 126 : 10 % Heading : 50 % Heading : 80 % Heading Soil moisture stress in all the vegetative stages lengthened vegetative growth and subsequently delayed heading. Stress at early vegetative stage (S-1) delayed heading by 13 days. Stress at active tillering (S-2) and maximum tillering delayed heading by 16 and 19 days respectively. Time to heading was little affected by nitrogen application
  15. 15. YIELD AND YIELD COMPONENTS 3000 N1 N2 N3 Filled Grain Ratio (%) 90 80 F ille d G ra in R a tio (% )) 2500 70 Y ie ld (k g /h a )) 2000 60 50 1500 40 1000 30 20 500 10 0 0 S0 S1 S2 S3 S4 S5 Stage of StressMoisture stress reduced grain yield averaged for N treatmentsStress during grain filling reduced grain yield by 50% due to poorgrain fillingStress at active tillering stage and maximum tillering reduced yieldby 18% and 19% respectively
  16. 16. Yield components cont… Mean grain weight was reduced by 10% and 7% in S-4 and S-5 Moisture stress at maximum tillering reduced grains per panicle only slightly Yield difference between rice stressed in the early vegetative stage and control was negligible due extended recovery period after stress Conclusion N application caused greater growth reduction in rice stressed in the active vegetative stage (S-2 & S-3), despite causing minor yield increases. N found to be effective in boosting vegetative recovery in rice stress in early vegetative stage rather than later vegetative growth. Rice found to be most sensitive to moisture stress after heading due to poor grain filling. This underscores the importance of supplementary irrigation during grain filling in drought prone environments

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