Browsing by Author "Ajith, K"

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Agroclimatology in crop planning for central zone of Kerala
(Department of Agricultural Meteorology, College of Horticulture, Vellanikkara, 1999) Ajith, K; Kesava Ravo, A V R
Effect of organic amendments on plant parasitic nematodes and soil micro-organisms
(Department of Entomology, College of Agriculture, Vellayani, 1992) Ajith, K; Sheela, M S
Field experiments conducted to evaluate the effect of neem and eupatorium leaves at two levels on plant parasitic and non-parasitic nematodes and soil micro-organisms in the rootzone of bhindi and cowpea in rainy and summer seasons revealed that neem and eupatorium leaf treatments (300g/plant or 15 t/ha) were found effective in controlling Helicotylenchus spp., R. reniformis and M. incognita in the rootzone. Lower dose (150g/plant) of neem was found sufficient to suppress the Helicotylenchus spp. In the rootzone of bhindi. Effect of these treatments persisted up to 75 D A S in rainy season and 45 DAS in summer season. The effect of lower doses also persisted up to 30 DAS. The predatory and saprophytic nematode population build up in the rootzone was enhanced by higher dose of eupatorium. The effect on predatory fauna persisted up to 75 D A S in the rootzone of two crops. But in cowpea the effect on saprophytic fauna persisted only up to 60 D A S. The microbial populations (bacteria, fungi and actinomycetes) were increased in the rootzone of bhindi and cowpea in two seasons by the application of eupatorium leaf at higher dose where as neem leaf (higher dose) reduced the microbial population. Only the fungal population increased by the application of neem leaf at higher dose during rainy season. There was seasonal variation in population build up of fungi and maximum effect was seen in rainy season. The biometric characters (number of leaves, height of plant, root weight and shoot weight) and yield of bhindi and cowpea increased significantly by the higher dose of neem and eupatorium leaf. For increasing the height, lower dose of neem, and, for yield lower dose of neem and eupatorium also were found effective. The population of nematodes in the roots at the termination of experiment was significantly reduced by the higher dose of neem and eupatorium in bhindi while lower dose was found effective protecting cowpea roots.
Growth and yield estimation of rice based on satelite data and land based observation using growing degree days(GDD)
(Department of Agricultural Meterology, College of Agriculture, Vellanikkara, 2024-03-21) Fazil; Ajith, K
Rice, the primary staple food for approximately 3.5 billion people worldwide, is supporting food security in numerous countries through irrigated as well as rainfed rice ecosystems. Elevated temperatures may lead to a decline in productivity, impacting the ability to feed future generations. To address this challenge, the utilization of temperature-based agrometeorological indices, such as Growing Degree Days (GDD) supported by satellite data, emerges as a valuable tool for predicting crop growth and yield across large areas. Growth and yield estimation of rice based on satellite data and land-based observation using growing degree days (GDD) conducted in the Department of Agricultural Meteorology, College of Agriculture, Vellanikkara during the year 2022-23 with the objective of establishing a relationship between GDD and performance of rice crop and to examine the possibilities of remote sensing tools to evaluate plant and GDD interactions to a wider area. The field experiment was conducted in two medium-duration rice varieties, Uma and Pournami, at the Regional Agricultural Research Station, Kumarakom during mundakan season of 2022-23, and was laid out in Randomized Block Design. The treatments consist of five dates of planting, viz. D1-5th September, D2-20th September, D3-5th October, D4-20th October, D5-5th November, with four replications. Various biometric observations, heat unit accumulations, yield and yield attributes were recorded at definite intervals. The study on phenology revealed that crop duration decreased from early planting to late planting in both varieties. Grain yield was significantly affected by the planting dates in both varieties. D1 planting produced the highest grain yield in both Uma (4388.8 kg ha-1) and Pournami (3715 kg ha-1) varieties, while D5 planting produced the lowest yield in Uma (2118.8 kg ha-1) and Pournami (2313.8 kg ha-1). The yield attributes were also significantly affected by planting dates and showed similar trend. Heat units like GDD and Photothermal units (PTU) were found to reduce in delayed planting. D2 recorded the highest GDD in both Uma (2055°C days) and Pournami (2090°C days). The lowest GDD was recorded by D5 planting in Uma (1820°C days) and Pournami (1872°C days). A linear regression equation was developed to predict yield for both varieties using GDD as independent variables. The results indicated that the Uma variety performed better than Pournami variety in the field experiment with respect to plant characters and yield. Palakkad district and Kuttanad. MODIS LST product (MOD11A2) 8-day composite was used to retrieve day and night land surface temperature for the mundakan rice growing season of 2022-23. A linear relationship was developed with MODIS LST and air temperature data obtained from the ground station. The developed relationship was then validated to ensure its accuracy and reliability. Daily maximum and minimum air temperature was estimated from MODIS LST using the linear equation during the crop season for the study locations. GDD was calculated, and it was employed to estimate the number of days required to attain various phenological stages of the mundakan rice. Validation of the predicted number of days in comparison with the observed showed a good relationship with R2 values of 0.82, 0.82, 0.80, 0.87, 0.86, and 0.81, and RMSE 0.42, 0.65, 0.72, 0.74, 0.84, 1.33 respectively, for the six phenophases of the rice crop. Further studies were done to assess the potential of GDD as an agroclimatic indicator for climate change in selected 9 locations in Palakkad and Kuttanad. The study attempted to understand the spatial and temporal distribution of GDD of mundakan rice over the past 30 years (1993-2022). The 30-year period were divided into six pentads. Additionally, GDD during three warming scenarios (+1°, +2° and +3°C rise of daily temperature from last pentad) were also studied. The research finding indicates that accumulated GDD was found to be higher at Kuttanad compared to Palakkad ie., GDD decreases from lower latitude to higher latitude. Chittur of Palakkad district had the lowest accumulation of GDD, while the highest was reported at Moncompu in Kuttanad in the last pentad and as well as during the three warming scenarios. Analysis of the 30 year GDD data of Palakkad revealed that an alternate warming and cooling trend is observed during the first four pentads (i.e. the period from 1993 to 2012) and during the last two pentads (ie. period from 2013 to 2022) the cooling trend is not visible. In Kuttanad region the warming trend is more predominant and the GDD values showed a steady increase form the first pentad to the last pentad. The GDD values seems to decrease from west to east in both Palakkad and Kuttanad.
Impact of climate change on livestock and poultry
(Department of Agricultural Meteorology, College of Horticulture, Kerala Agricultural University, 2020) Aswathi, K P; Ajith, K
Impact of climate change on production and nutritional qualitites of rice
(Department of Agricultural Meterology, College of Horticulture, Vellanikkara, 2020) Aswathi, K P; Ajith, K
Rice (Oryza sativa L.) is the major staple food for more than half of the world's population (FAO, 2013), accounting for approximately 30 percent of the total dietary intake, globally and in South Asia (Lobell et al., 2008). Rice production in the tropics is vulnerable to climatic factors, which affect the crop in various ways during different stages of its growth (Yoshida, 1973). The rising temperatures and carbon dioxide and uncertainties in rainfall associated with climate change may have serious direct and indirect consequences on rice production and nutritional aspects. Nowadays, most of the rice is currently cultivated in regions where temperatures are already above the optimum range for growth of rice. Therefore, any further rise in temperature during crop growth period may adversely affect the growth and yield of rice. The present experiment was aimed to study the impact of climate change on production and nutritional qualities of rice. Rice variety, Jyothi was raised at Regional Agricultural Research Station, Pattambi by adopting completely randomized design with two factors. The experiment was laid out with five dates of planting (June 1st, June 30th, October 1st, October 30th and January 1st) as first factor and the two growing conditions (open condition and climate controlled greenhouse) as second factor. Three replications were given for the experiment with ten pots under each replication. The future climate was estimated by climate change projections generated using ECHAM and GFDL-CM3 models for 2030, 2050 and 2080 based on scenarios RCP, 4.5 and 8.5. Duration taken for each phenophases found to vary for both the growing conditions in Jyothi. Plants grown under open condition took more days to attain different phenological stages. Phenophase duration was negatively influenced by maximum temperature. Plants grown under climate controlled greenhouse recorded significantly higher plant height and leaf area index when compared to plants grown under open condition. Yield recorded was maximum under open conditions compared to climate controlled greenhouse. October 30th planting showed significantly higher yield in both conditions. Similarly straw yield was significantly influenced by dates of planting and growing conditions. October 30st planting had higher straw yield compared to other dates of planting and plants grown under climate controlled green house gave higher straw yield compared to open condition. It was observed that increased minimum temperature had significant negative effect on grain and straw yield. Effect of dates of planting on dry matter accumulation at harvest was found to be significant. Maximum dry matter accumulation was recorded during October 30th planting and dry matter accumulations recorded during all other plantings were on par with each other. Maximum temperature and soil temperature showed negative influence on thousand grain weight under both the growing conditions. Cooking and nutritional quality parameters were found to be higher in plants grown under open condition, compared to that under climate controlled greenhouse. Milling percentage and head rice recovery found to be decreased with increase in maximum temperature. Higher maximum temperature had significant negative effect on strarch, amylose, protein, fat and mineral content in grains. Briefly, grain quality deteriorated under high temperature conditions. Performance of the CERES-RICE model was tested and evaluated using the calibrated genetic coefficients for the variety Jyothi. Observed grain yield, panicle initiation day, days to anthesis and physiological maturity days showed good agreement with simulated value. The simulation analysis as per the projected climate change scenarios for the period of 2030, 2050 and 2080 showed that among different date of planting, performance of rice variety Jyothi is better in October 1st planting. In RCP 4.5, which is the most likely scenario of India, the yield reduction will be 13.8, 16.9 and 24.5 percent respectively during 2030, 2050 and 2080. Whereas under RCP 8.5 scenario, yield reduction observed was 15.3, 27.4 and 39.7 percent respectively during 2030, 2050 and 2080. The yield reduction in almost all the planting dates under RCP 4.5 and RCP 8.5 scenarios was due to increased minimum and maximum temperature and increased rainfall during anthesis. In short, field experiment and impact studies using CERES-rice model give the similar results that increased temperature has a significant negative effect on yield and nutritional aspects of rice. Similarly increased rainfall at anthesis stage has adverse effects on crop performance.