Quantifying stripe rust reaction in wheat using remote sensing based

hand held NDVI sensor

Apoorva Arora Directorate of Wheat Research, Karnal

Normalized  difference  vegeta2on  index  (NDVI)    

   Ø  Func2on  of  incident  and  reflected  light                                                NDVI=      NIR  –  Red    ,                                                                                NIR  +  Red                      NIR  750-­‐1300  nm  

                                       Red  600-­‐700  nm    Ø  Foliar  pigments  dominate  reflectance  measurements    

 0<  NDVI<  1  

Stripe  Rust  and  NDVI  

 Ø  Breakdown  of  foliar  pigments  

Ø  Foliar  physiological  ac2vity  decreases  

Ø  Less  reflactance  of  infrared  by  healthy  vegeta2on  and  vice  versa  

Ø  Decrease  in  value  of  NDVI    

NASA  Earth  Observatory  (Illustra2on  by  Robert  Simmon)  

Why  NDVI  

Ø Most  sensors  provide  measurements  in  NIR  &  Red  por2on  of  spectrum  

 Ø Addi2ve  gene  governed  rust  resistance  geZng  more  a[en2on  than  ever  before  

 Ø Minor  varia2ons  can  be  captured  by  quan2ta2ve  varia2on  

High  Throughput  Screening  Gap  

 

Phen

otyping  

Gen

otyping  

Phenotyping  in  field  condi1ons…??  

Rust  Scoring  Methodology  

Satellite  based  Remote  sensing:  Limita2ons  

Ø Atmospheric  condi2ons  

Ø Satellite  geometry  &  calibera2on  

Ø Soil  backgrounds  

Ø Crop  canopy  

Ø Angle  of  solar  radia2on  incidence  

Ø Small  plots  can’t  be  used  for  measurements    

     

Objec2ve  

.    

     Quantifying stripe rust reaction in wheat using remote sensing based

hand held NDVI sensor  

Research  Methodology    

Study  Material  

322  genotypes  

Pedigree  analysis  

Diversity  analysis  

120    genotypes    

Released  varie1es,  Local  land  races,Elite  wheat    genotypes        

Represen1ng    each  group  

Field  Experiment  

LaZce  Design      

Plan2ng  Method  

Epiphyto2c  Condi2ons  

 Ø Epiphyto2c  condi2ons  created  by  plan2ng  suscep2ble  check  on  either  sides  of  plot  

Ø Inoculated  with  Yr27  virulent  race  78S84  of  Puccinia  striiformis  

 Equipment  

 Ø  Recorded  data  using  handheld  ac2ve  op2cal  GreenSeeker  

sensor  (Trimble  Industeries,  Inc.)    Ø NDVI  computed  from  reflectance  measurements  in  red  

(~660nm)&  near  infrared  (around  780nm)por2on  of  spectrum    Ø  Display  value  in  range  of  0.00  to  0.99  

RESULTS  

AUDPC  wise  distribu2on  of  genotypes  

Ø  AUDPC  computed  varied  from  0  to  2077  

Ø  Equal  number  of  genotypes  in  all  categories  except  in  AUDPC  range  of  1-­‐100  

NDVI    

Ø  Recorded  when  crop  showed  symptoms  of      maximum  infec2on  

 Ø  Value  of  NDVI  varied  from  0.46    to  0.69    Ø Mean  values  across  different  AUDPC  range:  0.58  to  0.69  

Ø  Value  reduced  with  increase  in  incidence  of  disease  

NDVI  vs  AUDPC  

Ø Regression  equa2on  for  NDVI  using  AUDPC  :  

         NDVI=0.663+-­‐6.165E-­‐5(AUDPC)t    Ø Significant  correla2on  depicted  by  r2  value  of  0.63    

ND

VI

AUDPC

Effect  of  Spot  Blotch  

Ø  Spectral  quality  of    reflected  light  from  leaves  manifested  in  leaf  color  

 Ø   NDVI  values  also  got  affected  by  

the  presence  of  spot  blotch  

Ø  Quan2fied  value  of  NDVI  due  to  blotch  alone  was  added  (if  required)    

Ø Mean  NDVI  values  amer  correc2on:  0.64  to  0.76  

 Ø  Regression  equa2on  for      Corrected  NDVI  vs  AUDPC:      NDVI=0.738  +-­‐7.061E-­‐5(AUDPC)t  

 

Ø  Correla2on  (r2  )  value  improved  to  0.69  

     

 

ND

VI

AUDPC

Plant  physiological  factors  AUDPC  

 Ø  Correla2on  coefficient  showed  

significant  values  

Ø  Correla2on  value  improved  as  categories  shimed  from  predominantly  resistant  to    

         suscep2ble  types  

AUDPC  Range  

Coeff.  of  determina2on  (r2)  

 Correla2on  coefficient  

0-­‐200   0.20  

 -­‐0.45  

>200   0.72  

 -­‐0.85  

             

Plant  Height  

 

Plant  Height  (in  cm)  

No.  of  genotypes  

Coeff.  of  determina1on  (r2)  

Correla1on  coefficient  

65-­‐74   3   0.76   -­‐0.87  

75-­‐84   15   0.62   -­‐0.79  

85-­‐94   50   0.62   -­‐0.79  

95-­‐104   35   0.73   -­‐0.85  

105-­‐114   14   0.57   -­‐0.76  

115-­‐124   2   1.00   -­‐1  

Ø  Value  of  correla2on  coefficient  increased  as  taller  types  were                                more  suscep2ble  

Ø  Range  of  coefficient  :  0.76  to  1.00  

 

   

 

Ø Similar  value  of  correla2on  coefficient  obtained  

Ø No  significant  difference  between  categories            was  no2ced  

   

Waxiness  and  Early  Growth  Habit  

 

Conclusion  

Ø With  increasing  a[en2on  towards  quan2ta2ve  rust  resistance  studies,  innova2ve  tools  &  techniques  are  needed  

Ø NDVI  sensor  technique  provides  mean  value  of  several  images  captured  from  the  plot  as  against  single  frame  observa2on  by  human  eye  

Ø  High  correla2on  value  indicates  suitability  of    the  instrument  as  an  useful  tool  for  accurate  rust  data  recording  

 Ø  Accuracy  of  this  method  improves  when  catagoriza2on  of  

genotypes  accrued  to  predominance  of    susep2bility  

 

Inspiration behind work…

Dr.  Indu  Sharma  Project  Director  

Directorate  of  Wheat  Research    Karnal  

Dr.  M.  S.  Saharan  Principal  Scien1st  

Dr.  R.K.    Sharma  Principal  Scien1st  

Dr.  K.  Venkatesh  Scien1st  

Davender  Sharma  Sr.  Research  Fellow  

Thank You