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Estimating yield of sorghum using root zone water balance model and spectral characteristics of crop in a dryland Alfisol

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Title Estimating yield of sorghum using root zone water balance model and spectral characteristics of crop in a dryland Alfisol
Estimating yield of sorghum using root zone water balance model and spectral characteristics of crop in a dryland Alfisol
 
Creator ICAR_CRIDA
 
Subject Toposequence Vegetation indices Water production function Water stress index
 
Description Not Available
This study investigated the relationship between sorghum grain yield for a range of soil
depths, with the seasonal crop water stress index based on relative evapotranspiration
deficits and spectral vegetation indices. A root zone water balance model was used to
evaluate seasonal soil water fluctuations and actual evapotranspiration within a toposequence;
soil depth varied between 30 and 75 cm and available water capacity ranged from
6.9 to 12.6% (v/v, %). An empirical model was used to determine root growth. Runoff was
estimated from rainfall data using the curve number techniques of the Soil Conservation
Services, combined with a soil water-accounting procedure. The high r2 values between
modeled and observed values of soil water in the root zone (r2 > 0.70, significant at P < 0.001)
and runoff (r2 = 0.95, significant at P < 0.001) indicated good agreement between the model
output and observed values. Canopy reflectance was measured during the entire crop
growth period and the following spectral indices were calculated: simple ratio, normalized
difference vegetation index (NDVI), green NDVI, perpendicular vegetation index, soil
adjusted vegetation index (SAVI) and modified SAVI (MSAVI). All the vegetation indices,
except for the perpendicular vegetation index, measured from booting to anthesis stage,
were positively correlated with leaf area index (LAI) and yield. The correlation coefficient for
spectral indices with dry biomass was relatively less than for LAI and yield. Modified SAVI
recorded from booting to milk-grain stage gave the highest average correlation coefficient
with grain yield. Additive and multiplicative forms of water-production functions, as well as
water stress index calculated from water budget model, were used to predict crop yield. A
multiple regression was carried out with yield, for the years 2001–2003, as the dependent
variable and MSAVI, from the booting to the milk-grain stage of crop and relative yield
values, calculated using both additive and multiplicative water production functions as well
as water stress index, as the independent variables. The multiplicative model and MSAVI,
recorded during the heading stage of crop growth, gave the highest coefficient of determination
(r2 = 0.682, significant at P < 0.001). The multiple regression equation was tested for
yield data recorded during 2004; the deviation between observed and estimated yields varied
from 6.2 to 9.4%. The water budget model, along with spectral vegetation indices, gave
satisfactory estimates of sorghum grain yields and appears to be a useful tool to estimate
yield as a function of soil depth and available water.
Not Available
 
Date 2020-02-25T08:49:20Z
2020-02-25T08:49:20Z
2007
 
Type Technical Report
 
Identifier Not Available
Not Available
http://krishi.icar.gov.in/jspui/handle/123456789/32833
 
Language English
 
Relation Not Available;
 
Publisher Sharma, K.L.,