The Experts below are selected from a list of 246 Experts worldwide ranked by ideXlab platform
Vijaya P Kumar - One of the best experts on this subject based on the ideXlab platform.
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use of remote sensing for drought stress monitoring yield prediction and varietal evaluation in Castor Beans ricinus communis l
International Journal of Remote Sensing, 2005Co-Authors: Vijaya P Kumar, Y S Ramakrishna, D Bhaskara V Rao, G Sridhar, Srinivasa G Rao, G G S N RaoAbstract:The current study was taken up to investigate the utility of remote sensing tools like infrared thermometer and spectral radiometer for screening of germplasm, stress monitoring and yield prediction in Castor Beans (Ricinus communis L.). The study was carried out through field experiments conducted for six years (1994–1999) at Hayatnagar Research Farm, Hyderabad, India. In each year, four cultivars of Castor Beans, viz. VP‐1, 48‐1, GCH‐4 and Aruna, were planted on two different dates maintaining an interval of 6–8 weeks so as to expose the crop to different environments. The infrared thermometric observations like canopy–air temperature differential (T c–T a) explained 50–60% variation in soil moisture status and showed a significant relationship with soil moisture. Yield of Castor Beans exhibited significant inverse relationship with T c–T a, which explained 59% of variation in yield. The hybrid GCH‐4, registering comparatively lesser mean T c–T a over the entire growing period, established itself as a b...
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assessment of plant extractable soil water in Castor Beans ricinus communis l using infrared thermometry
Agricultural Water Management, 1999Co-Authors: Vijaya P Kumar, Y S Ramakrishna, B Ramana V Rao, I R Khandgonda, U S Victor, N N Srivastava, G G S N RaoAbstract:Abstract Assessment of plant-extractable soil water from experimental plots using infrared thermometer was carried out through a field experiment on rainfed Castor Beans (Ricinus communis L.) conducted for 2 years (1992–1993) at Hyderabad, India. The Castor Beans (cultivar: Aruna) were planted on three different dates in both years. Attempts were made to normalize canopy temperature and stress degree days (SDD) for environmental variability to accurately assess the plant-extractable soil water (PESW) using an Infrared thermometer. Normalization of SDD for variability of temperature and saturation deficit (division of SDD by air temperature and saturation deficit), greatly improved the predictability of the soil water status (PESW), than that based on SDD. The coefficients of determination (R2 values) of the relationship between PESW and SDD after normalization were 0.65 and 0.61 in the years 1992 and 1993, compared to 0.19 and 0.08 before normalization, in respective years. This simple method of normalization of SDD (the division of SDD with weather parameters), which seems to be a promising technique for assessing the soil water status through remote sensing techniques in semi-arid tropics (SAT) needs to be further tested in other environmental conditions and also in other crops, for realising the long-felt objective of assessing soil moisture status with the help of infrared thermometry.
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influence of moisture thermal and photoperiodic regimes on the productivity of Castor Beans ricinus communis l
Agricultural and Forest Meteorology, 1997Co-Authors: Vijaya P Kumar, Y S Ramakrishna, B Ramana V Rao, U S Victor, N N Srivastava, A Subba V M RaoAbstract:Abstract Field experiments on rainfed Castor Beans ( Ricinus communis L.) were conducted for 4 consecutive years (1990–1993) to study the effect of weather on the yields of different spike orders of Castor, viz., primaries, secondaries and tertiaries. In these experiments, Castor Cv. Aruna was planted on three different dates (treatments) in each year. The results from this study revealed that higher bean yield can be achieved by planting the crop on an early date, i.e., in June. Early planting results in higher yield of primaries and lower yield of tertiaries compared to delayed planting and vice versa. Though primaries were main contributors to total yield (59%), their loss due to either biotic or abiotic stress was compensated by later developed spikes (secondaries and tertiaries). Multiple regression equations were worked out between yields from different spike orders and specific weather parameters like degree days, photo-periods and moisture adequacy index during their reproductive periods. The moisture adequacy index is the ratio of the actual to potential evapotranspiration. These studies revealed that primaries are mostly influenced by photo-period (61%) and to a lesser extent by moisture adequacy index (39%). Secondaries were mainly influenced by moisture adequacy index (83%) whereas tertiaries are not found to be influenced independently by any weather parameter but were inversely influenced by the interaction of moisture adequacy index and degree days (93%). Total yield, i.e., sum of the yield of primaries, secondaries and tertiaries was positively influenced by the moisture adequacy index and degree days during the total reproductive period (initiation of primaries to maturity of tertiaries). The model predicting total yield can be utilised to identify optimum planting period based on the climatic data of the region. The results from this study will be of further use in formulating suitable crop growth models to simulate yields of Castor and also in delineating areas with optimum agroclimatic environments for achieving potential productivity of Castor.
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radiation and water use efficiencies of rainfed Castor Beans ricinus communis l in relation to different weather parameters
Agricultural and Forest Meteorology, 1996Co-Authors: Vijaya P Kumar, Y S Ramakrishna, U S Victor, N N Srivastava, Gangadhar D Rao, A Subba V M Rao, B Ramana V RaoAbstract:Abstract Field experiments on rainfed Castor Beans ( Ricinus communis L.) were conducted for 4 years (1990–1993) to explain the variability in radiation use efficiency (RUE) and water use efficiency (WUE) in relation to meteorological parameters. In these experiments Castor c.v. Aruna was sown on three different dates (treatments) in each year. The results from this study indicate that both RUE and WUE vary from year to year and also were influenced by the planting dates. Variations in RUE and WUE ranged from 0.79–1.19 g MJ −1 and 0.72–1.25 g kg −1 , respectively. The variability in RUE and WUE before and after flower initiation were quite contrasting. The variability in RUE and WUE was associated with saturation vapour pressure deficit (SVPD), drought index, temperature and wind velocity. RUE was related positively with SVPD and wind velocity and negatively with drought index and temperature. WUE showed inverse relationships with SVPD and temperature and a direct relation with wind velocity. The study emphasises the need for incorporation of the effect of weather on RUE and WUE in the algorithms for biomass estimation of crop simulation models.
B Ramana V Rao - One of the best experts on this subject based on the ideXlab platform.
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assessment of plant extractable soil water in Castor Beans ricinus communis l using infrared thermometry
Agricultural Water Management, 1999Co-Authors: Vijaya P Kumar, Y S Ramakrishna, B Ramana V Rao, I R Khandgonda, U S Victor, N N Srivastava, G G S N RaoAbstract:Abstract Assessment of plant-extractable soil water from experimental plots using infrared thermometer was carried out through a field experiment on rainfed Castor Beans (Ricinus communis L.) conducted for 2 years (1992–1993) at Hyderabad, India. The Castor Beans (cultivar: Aruna) were planted on three different dates in both years. Attempts were made to normalize canopy temperature and stress degree days (SDD) for environmental variability to accurately assess the plant-extractable soil water (PESW) using an Infrared thermometer. Normalization of SDD for variability of temperature and saturation deficit (division of SDD by air temperature and saturation deficit), greatly improved the predictability of the soil water status (PESW), than that based on SDD. The coefficients of determination (R2 values) of the relationship between PESW and SDD after normalization were 0.65 and 0.61 in the years 1992 and 1993, compared to 0.19 and 0.08 before normalization, in respective years. This simple method of normalization of SDD (the division of SDD with weather parameters), which seems to be a promising technique for assessing the soil water status through remote sensing techniques in semi-arid tropics (SAT) needs to be further tested in other environmental conditions and also in other crops, for realising the long-felt objective of assessing soil moisture status with the help of infrared thermometry.
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influence of moisture thermal and photoperiodic regimes on the productivity of Castor Beans ricinus communis l
Agricultural and Forest Meteorology, 1997Co-Authors: Vijaya P Kumar, Y S Ramakrishna, B Ramana V Rao, U S Victor, N N Srivastava, A Subba V M RaoAbstract:Abstract Field experiments on rainfed Castor Beans ( Ricinus communis L.) were conducted for 4 consecutive years (1990–1993) to study the effect of weather on the yields of different spike orders of Castor, viz., primaries, secondaries and tertiaries. In these experiments, Castor Cv. Aruna was planted on three different dates (treatments) in each year. The results from this study revealed that higher bean yield can be achieved by planting the crop on an early date, i.e., in June. Early planting results in higher yield of primaries and lower yield of tertiaries compared to delayed planting and vice versa. Though primaries were main contributors to total yield (59%), their loss due to either biotic or abiotic stress was compensated by later developed spikes (secondaries and tertiaries). Multiple regression equations were worked out between yields from different spike orders and specific weather parameters like degree days, photo-periods and moisture adequacy index during their reproductive periods. The moisture adequacy index is the ratio of the actual to potential evapotranspiration. These studies revealed that primaries are mostly influenced by photo-period (61%) and to a lesser extent by moisture adequacy index (39%). Secondaries were mainly influenced by moisture adequacy index (83%) whereas tertiaries are not found to be influenced independently by any weather parameter but were inversely influenced by the interaction of moisture adequacy index and degree days (93%). Total yield, i.e., sum of the yield of primaries, secondaries and tertiaries was positively influenced by the moisture adequacy index and degree days during the total reproductive period (initiation of primaries to maturity of tertiaries). The model predicting total yield can be utilised to identify optimum planting period based on the climatic data of the region. The results from this study will be of further use in formulating suitable crop growth models to simulate yields of Castor and also in delineating areas with optimum agroclimatic environments for achieving potential productivity of Castor.
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radiation and water use efficiencies of rainfed Castor Beans ricinus communis l in relation to different weather parameters
Agricultural and Forest Meteorology, 1996Co-Authors: Vijaya P Kumar, Y S Ramakrishna, U S Victor, N N Srivastava, Gangadhar D Rao, A Subba V M Rao, B Ramana V RaoAbstract:Abstract Field experiments on rainfed Castor Beans ( Ricinus communis L.) were conducted for 4 years (1990–1993) to explain the variability in radiation use efficiency (RUE) and water use efficiency (WUE) in relation to meteorological parameters. In these experiments Castor c.v. Aruna was sown on three different dates (treatments) in each year. The results from this study indicate that both RUE and WUE vary from year to year and also were influenced by the planting dates. Variations in RUE and WUE ranged from 0.79–1.19 g MJ −1 and 0.72–1.25 g kg −1 , respectively. The variability in RUE and WUE before and after flower initiation were quite contrasting. The variability in RUE and WUE was associated with saturation vapour pressure deficit (SVPD), drought index, temperature and wind velocity. RUE was related positively with SVPD and wind velocity and negatively with drought index and temperature. WUE showed inverse relationships with SVPD and temperature and a direct relation with wind velocity. The study emphasises the need for incorporation of the effect of weather on RUE and WUE in the algorithms for biomass estimation of crop simulation models.
Y S Ramakrishna - One of the best experts on this subject based on the ideXlab platform.
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use of remote sensing for drought stress monitoring yield prediction and varietal evaluation in Castor Beans ricinus communis l
International Journal of Remote Sensing, 2005Co-Authors: Vijaya P Kumar, Y S Ramakrishna, D Bhaskara V Rao, G Sridhar, Srinivasa G Rao, G G S N RaoAbstract:The current study was taken up to investigate the utility of remote sensing tools like infrared thermometer and spectral radiometer for screening of germplasm, stress monitoring and yield prediction in Castor Beans (Ricinus communis L.). The study was carried out through field experiments conducted for six years (1994–1999) at Hayatnagar Research Farm, Hyderabad, India. In each year, four cultivars of Castor Beans, viz. VP‐1, 48‐1, GCH‐4 and Aruna, were planted on two different dates maintaining an interval of 6–8 weeks so as to expose the crop to different environments. The infrared thermometric observations like canopy–air temperature differential (T c–T a) explained 50–60% variation in soil moisture status and showed a significant relationship with soil moisture. Yield of Castor Beans exhibited significant inverse relationship with T c–T a, which explained 59% of variation in yield. The hybrid GCH‐4, registering comparatively lesser mean T c–T a over the entire growing period, established itself as a b...
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assessment of plant extractable soil water in Castor Beans ricinus communis l using infrared thermometry
Agricultural Water Management, 1999Co-Authors: Vijaya P Kumar, Y S Ramakrishna, B Ramana V Rao, I R Khandgonda, U S Victor, N N Srivastava, G G S N RaoAbstract:Abstract Assessment of plant-extractable soil water from experimental plots using infrared thermometer was carried out through a field experiment on rainfed Castor Beans (Ricinus communis L.) conducted for 2 years (1992–1993) at Hyderabad, India. The Castor Beans (cultivar: Aruna) were planted on three different dates in both years. Attempts were made to normalize canopy temperature and stress degree days (SDD) for environmental variability to accurately assess the plant-extractable soil water (PESW) using an Infrared thermometer. Normalization of SDD for variability of temperature and saturation deficit (division of SDD by air temperature and saturation deficit), greatly improved the predictability of the soil water status (PESW), than that based on SDD. The coefficients of determination (R2 values) of the relationship between PESW and SDD after normalization were 0.65 and 0.61 in the years 1992 and 1993, compared to 0.19 and 0.08 before normalization, in respective years. This simple method of normalization of SDD (the division of SDD with weather parameters), which seems to be a promising technique for assessing the soil water status through remote sensing techniques in semi-arid tropics (SAT) needs to be further tested in other environmental conditions and also in other crops, for realising the long-felt objective of assessing soil moisture status with the help of infrared thermometry.
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influence of moisture thermal and photoperiodic regimes on the productivity of Castor Beans ricinus communis l
Agricultural and Forest Meteorology, 1997Co-Authors: Vijaya P Kumar, Y S Ramakrishna, B Ramana V Rao, U S Victor, N N Srivastava, A Subba V M RaoAbstract:Abstract Field experiments on rainfed Castor Beans ( Ricinus communis L.) were conducted for 4 consecutive years (1990–1993) to study the effect of weather on the yields of different spike orders of Castor, viz., primaries, secondaries and tertiaries. In these experiments, Castor Cv. Aruna was planted on three different dates (treatments) in each year. The results from this study revealed that higher bean yield can be achieved by planting the crop on an early date, i.e., in June. Early planting results in higher yield of primaries and lower yield of tertiaries compared to delayed planting and vice versa. Though primaries were main contributors to total yield (59%), their loss due to either biotic or abiotic stress was compensated by later developed spikes (secondaries and tertiaries). Multiple regression equations were worked out between yields from different spike orders and specific weather parameters like degree days, photo-periods and moisture adequacy index during their reproductive periods. The moisture adequacy index is the ratio of the actual to potential evapotranspiration. These studies revealed that primaries are mostly influenced by photo-period (61%) and to a lesser extent by moisture adequacy index (39%). Secondaries were mainly influenced by moisture adequacy index (83%) whereas tertiaries are not found to be influenced independently by any weather parameter but were inversely influenced by the interaction of moisture adequacy index and degree days (93%). Total yield, i.e., sum of the yield of primaries, secondaries and tertiaries was positively influenced by the moisture adequacy index and degree days during the total reproductive period (initiation of primaries to maturity of tertiaries). The model predicting total yield can be utilised to identify optimum planting period based on the climatic data of the region. The results from this study will be of further use in formulating suitable crop growth models to simulate yields of Castor and also in delineating areas with optimum agroclimatic environments for achieving potential productivity of Castor.
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radiation and water use efficiencies of rainfed Castor Beans ricinus communis l in relation to different weather parameters
Agricultural and Forest Meteorology, 1996Co-Authors: Vijaya P Kumar, Y S Ramakrishna, U S Victor, N N Srivastava, Gangadhar D Rao, A Subba V M Rao, B Ramana V RaoAbstract:Abstract Field experiments on rainfed Castor Beans ( Ricinus communis L.) were conducted for 4 years (1990–1993) to explain the variability in radiation use efficiency (RUE) and water use efficiency (WUE) in relation to meteorological parameters. In these experiments Castor c.v. Aruna was sown on three different dates (treatments) in each year. The results from this study indicate that both RUE and WUE vary from year to year and also were influenced by the planting dates. Variations in RUE and WUE ranged from 0.79–1.19 g MJ −1 and 0.72–1.25 g kg −1 , respectively. The variability in RUE and WUE before and after flower initiation were quite contrasting. The variability in RUE and WUE was associated with saturation vapour pressure deficit (SVPD), drought index, temperature and wind velocity. RUE was related positively with SVPD and wind velocity and negatively with drought index and temperature. WUE showed inverse relationships with SVPD and temperature and a direct relation with wind velocity. The study emphasises the need for incorporation of the effect of weather on RUE and WUE in the algorithms for biomass estimation of crop simulation models.
U S Victor - One of the best experts on this subject based on the ideXlab platform.
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assessment of plant extractable soil water in Castor Beans ricinus communis l using infrared thermometry
Agricultural Water Management, 1999Co-Authors: Vijaya P Kumar, Y S Ramakrishna, B Ramana V Rao, I R Khandgonda, U S Victor, N N Srivastava, G G S N RaoAbstract:Abstract Assessment of plant-extractable soil water from experimental plots using infrared thermometer was carried out through a field experiment on rainfed Castor Beans (Ricinus communis L.) conducted for 2 years (1992–1993) at Hyderabad, India. The Castor Beans (cultivar: Aruna) were planted on three different dates in both years. Attempts were made to normalize canopy temperature and stress degree days (SDD) for environmental variability to accurately assess the plant-extractable soil water (PESW) using an Infrared thermometer. Normalization of SDD for variability of temperature and saturation deficit (division of SDD by air temperature and saturation deficit), greatly improved the predictability of the soil water status (PESW), than that based on SDD. The coefficients of determination (R2 values) of the relationship between PESW and SDD after normalization were 0.65 and 0.61 in the years 1992 and 1993, compared to 0.19 and 0.08 before normalization, in respective years. This simple method of normalization of SDD (the division of SDD with weather parameters), which seems to be a promising technique for assessing the soil water status through remote sensing techniques in semi-arid tropics (SAT) needs to be further tested in other environmental conditions and also in other crops, for realising the long-felt objective of assessing soil moisture status with the help of infrared thermometry.
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influence of moisture thermal and photoperiodic regimes on the productivity of Castor Beans ricinus communis l
Agricultural and Forest Meteorology, 1997Co-Authors: Vijaya P Kumar, Y S Ramakrishna, B Ramana V Rao, U S Victor, N N Srivastava, A Subba V M RaoAbstract:Abstract Field experiments on rainfed Castor Beans ( Ricinus communis L.) were conducted for 4 consecutive years (1990–1993) to study the effect of weather on the yields of different spike orders of Castor, viz., primaries, secondaries and tertiaries. In these experiments, Castor Cv. Aruna was planted on three different dates (treatments) in each year. The results from this study revealed that higher bean yield can be achieved by planting the crop on an early date, i.e., in June. Early planting results in higher yield of primaries and lower yield of tertiaries compared to delayed planting and vice versa. Though primaries were main contributors to total yield (59%), their loss due to either biotic or abiotic stress was compensated by later developed spikes (secondaries and tertiaries). Multiple regression equations were worked out between yields from different spike orders and specific weather parameters like degree days, photo-periods and moisture adequacy index during their reproductive periods. The moisture adequacy index is the ratio of the actual to potential evapotranspiration. These studies revealed that primaries are mostly influenced by photo-period (61%) and to a lesser extent by moisture adequacy index (39%). Secondaries were mainly influenced by moisture adequacy index (83%) whereas tertiaries are not found to be influenced independently by any weather parameter but were inversely influenced by the interaction of moisture adequacy index and degree days (93%). Total yield, i.e., sum of the yield of primaries, secondaries and tertiaries was positively influenced by the moisture adequacy index and degree days during the total reproductive period (initiation of primaries to maturity of tertiaries). The model predicting total yield can be utilised to identify optimum planting period based on the climatic data of the region. The results from this study will be of further use in formulating suitable crop growth models to simulate yields of Castor and also in delineating areas with optimum agroclimatic environments for achieving potential productivity of Castor.
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radiation and water use efficiencies of rainfed Castor Beans ricinus communis l in relation to different weather parameters
Agricultural and Forest Meteorology, 1996Co-Authors: Vijaya P Kumar, Y S Ramakrishna, U S Victor, N N Srivastava, Gangadhar D Rao, A Subba V M Rao, B Ramana V RaoAbstract:Abstract Field experiments on rainfed Castor Beans ( Ricinus communis L.) were conducted for 4 years (1990–1993) to explain the variability in radiation use efficiency (RUE) and water use efficiency (WUE) in relation to meteorological parameters. In these experiments Castor c.v. Aruna was sown on three different dates (treatments) in each year. The results from this study indicate that both RUE and WUE vary from year to year and also were influenced by the planting dates. Variations in RUE and WUE ranged from 0.79–1.19 g MJ −1 and 0.72–1.25 g kg −1 , respectively. The variability in RUE and WUE before and after flower initiation were quite contrasting. The variability in RUE and WUE was associated with saturation vapour pressure deficit (SVPD), drought index, temperature and wind velocity. RUE was related positively with SVPD and wind velocity and negatively with drought index and temperature. WUE showed inverse relationships with SVPD and temperature and a direct relation with wind velocity. The study emphasises the need for incorporation of the effect of weather on RUE and WUE in the algorithms for biomass estimation of crop simulation models.
N N Srivastava - One of the best experts on this subject based on the ideXlab platform.
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assessment of plant extractable soil water in Castor Beans ricinus communis l using infrared thermometry
Agricultural Water Management, 1999Co-Authors: Vijaya P Kumar, Y S Ramakrishna, B Ramana V Rao, I R Khandgonda, U S Victor, N N Srivastava, G G S N RaoAbstract:Abstract Assessment of plant-extractable soil water from experimental plots using infrared thermometer was carried out through a field experiment on rainfed Castor Beans (Ricinus communis L.) conducted for 2 years (1992–1993) at Hyderabad, India. The Castor Beans (cultivar: Aruna) were planted on three different dates in both years. Attempts were made to normalize canopy temperature and stress degree days (SDD) for environmental variability to accurately assess the plant-extractable soil water (PESW) using an Infrared thermometer. Normalization of SDD for variability of temperature and saturation deficit (division of SDD by air temperature and saturation deficit), greatly improved the predictability of the soil water status (PESW), than that based on SDD. The coefficients of determination (R2 values) of the relationship between PESW and SDD after normalization were 0.65 and 0.61 in the years 1992 and 1993, compared to 0.19 and 0.08 before normalization, in respective years. This simple method of normalization of SDD (the division of SDD with weather parameters), which seems to be a promising technique for assessing the soil water status through remote sensing techniques in semi-arid tropics (SAT) needs to be further tested in other environmental conditions and also in other crops, for realising the long-felt objective of assessing soil moisture status with the help of infrared thermometry.
-
influence of moisture thermal and photoperiodic regimes on the productivity of Castor Beans ricinus communis l
Agricultural and Forest Meteorology, 1997Co-Authors: Vijaya P Kumar, Y S Ramakrishna, B Ramana V Rao, U S Victor, N N Srivastava, A Subba V M RaoAbstract:Abstract Field experiments on rainfed Castor Beans ( Ricinus communis L.) were conducted for 4 consecutive years (1990–1993) to study the effect of weather on the yields of different spike orders of Castor, viz., primaries, secondaries and tertiaries. In these experiments, Castor Cv. Aruna was planted on three different dates (treatments) in each year. The results from this study revealed that higher bean yield can be achieved by planting the crop on an early date, i.e., in June. Early planting results in higher yield of primaries and lower yield of tertiaries compared to delayed planting and vice versa. Though primaries were main contributors to total yield (59%), their loss due to either biotic or abiotic stress was compensated by later developed spikes (secondaries and tertiaries). Multiple regression equations were worked out between yields from different spike orders and specific weather parameters like degree days, photo-periods and moisture adequacy index during their reproductive periods. The moisture adequacy index is the ratio of the actual to potential evapotranspiration. These studies revealed that primaries are mostly influenced by photo-period (61%) and to a lesser extent by moisture adequacy index (39%). Secondaries were mainly influenced by moisture adequacy index (83%) whereas tertiaries are not found to be influenced independently by any weather parameter but were inversely influenced by the interaction of moisture adequacy index and degree days (93%). Total yield, i.e., sum of the yield of primaries, secondaries and tertiaries was positively influenced by the moisture adequacy index and degree days during the total reproductive period (initiation of primaries to maturity of tertiaries). The model predicting total yield can be utilised to identify optimum planting period based on the climatic data of the region. The results from this study will be of further use in formulating suitable crop growth models to simulate yields of Castor and also in delineating areas with optimum agroclimatic environments for achieving potential productivity of Castor.
-
radiation and water use efficiencies of rainfed Castor Beans ricinus communis l in relation to different weather parameters
Agricultural and Forest Meteorology, 1996Co-Authors: Vijaya P Kumar, Y S Ramakrishna, U S Victor, N N Srivastava, Gangadhar D Rao, A Subba V M Rao, B Ramana V RaoAbstract:Abstract Field experiments on rainfed Castor Beans ( Ricinus communis L.) were conducted for 4 years (1990–1993) to explain the variability in radiation use efficiency (RUE) and water use efficiency (WUE) in relation to meteorological parameters. In these experiments Castor c.v. Aruna was sown on three different dates (treatments) in each year. The results from this study indicate that both RUE and WUE vary from year to year and also were influenced by the planting dates. Variations in RUE and WUE ranged from 0.79–1.19 g MJ −1 and 0.72–1.25 g kg −1 , respectively. The variability in RUE and WUE before and after flower initiation were quite contrasting. The variability in RUE and WUE was associated with saturation vapour pressure deficit (SVPD), drought index, temperature and wind velocity. RUE was related positively with SVPD and wind velocity and negatively with drought index and temperature. WUE showed inverse relationships with SVPD and temperature and a direct relation with wind velocity. The study emphasises the need for incorporation of the effect of weather on RUE and WUE in the algorithms for biomass estimation of crop simulation models.