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ThesisItem Open Access Crops weather relationship in rice(Department of Agricultural Meteorology, College of Horticulture,Vellanikkara, 2000) Sunil, K M; KAU; Kesava Rao, A V RAn experiment was conducted in the Agricultural research Station, Mannuthy during first, second and third crop seasons of 1998-99 to study the crop weather relationship in rice variety 'Kanchana'. The experiment was laid out in randomised block design with three replications. The treatment consisted of three dates of planting in each season i.e., 1 s\ i s" and 30th of June, 1 st 15th and 30th of October and 1 st, 15th and 30th of January. Observations on morphological and yield attributes were recorded during the course of investigation. The daily values of weather elements viz., maximum and minimum surface air temperature, bright sunshine, morning and afternoon relative humidity and wind speed were collected from the Principle Agro Meteorological Station, College of Horticulture, Vellanikkara, to work out the crop weather relationships in rice. . Crops transplanted on 1 st is" and 30tl) of October and 1 st 15th of June were significantly superior in terms of grain yield, panicle number, number of filled grains/panicle, number of leaves, plant biomass, number of tillers and leaf area index. The crop weather relationship studies showed that the wind speed, minimum temperature and mean temperature during flowering to maturity had a significant negative correlation with grain yield. But morning relative humidity and mean relative humidity during transplanting to panicle initiation stage had a significant positive influence on ultimate grain yield. The wind speed, mean temperature, temperature range, RH1-RH2 and solar radiation during vegetative stage were negatively correlated with the straw yield. Maximum temperature during beginning of grain filling to maturity stage also had a negative correlation. But increase in mimmum temperature, mean relative humidity, morning and afternoon relative humidities during transplanting to flowering stage was significantly increase the straw yield as there was a positive correlation. The regression equations developed in the study predicted the grain yield, straw yield, duration of vegetative phase and maximum leaf area index well and a close relation existed between observed and estimated yield. Based on the experimental data, minimum data set for the validation of rice model of the IBSNAT has been generated.ThesisItem Open Access Climatic variability and small cardamom (Elettaria cardamomum Maton) production across the Westren Ghats(Department of Agricultural Meteorology, College of Horticulture, Vellanikkara, 2004) Manikandan, N; PrasadaRao, G S L H VA study was undertaken at the Department of Agricultural Meteorology, College of Horticulture, Kerala Agricultural University, Vellanikkara to analyse the variability of rainfall and surface air temperature over a period of time and its influence on the cardamom production and productivity across the Western Ghats for which the monthly data on rainfall, temperature (maximum and minimum) and nutritional status of soils were collected from six selected locations across the cardamom tract along with the data on area and production of small cardamom. The annual rainfall and rainfall during southwest monsoon (J une-Sep) increases from south to north across the cardamom tract and western parts (Kerala and Karnataka) of the Western Ghats receive better rainfall when compared to that of eastern parts (Tamil Nadu). The reverse trend was noticed during post monsoon (Oct- Nov) and winter (Dec-Feb) and eastern parts receive more rainfall than western parts. In summer (Mar-May), Kerala and Tamil Nadu receive relatively more rainfall than Karnataka. Trend analysis in rainfall revealed that a declining trend was noticed in annual rainfall at all the locations except Pampadumpara and Madikeri. Similar was the case during southwest monsoon except at Madikeri. In other seasons, no such uniform increasing or decreasing trend was noticed across the cardamom tract except at Thandikudi, where rainfall was declining in all seasons. The surface air temperature and its range were high (5.3 -15.9° C) over Karnataka, followed by Kerala (5.2 -11.7° C) and Tamil Nadu (6.9 -10.7 ° C). In majority of the locations, an increasing trend in annual maximum temperature was noticed. It was true in the case of southwest monsoon and post monsoon periods while a declining during winter and summer. Interestingly, an increasing trend was noticed in majority of the locations in the case of minimum temperature. It reflected on the temperature range also at fifty per cent of the locations (Pampadumpara, Madikeri and Thandikudi) during southwest and post monsoon seasons. It was reverse during winter and summer at all the locations except Saklespur and Mudigere. The study on the trends in moisture index (Im) showed that it declined at all the locations during southwest monsoon and annually except at Madikeri. During post monsoon and winter, an increasing trend in moisture index was noticed at all the locations except Thandikudi in post monsoon period. All the locations except at Pampadumpara, showed a declining trend in moisture index during summer. It was also noticed that the intensity of aridity was high towards north of cardamom tract. Studies on agroclimatic zonation of small cardamom revealed that the production potential of Zone I was relatively better (>200 kg / ha) when compared to that of Zone II and III across the Western Ghats, where the length of crop growing season was more than 300 days with annual Ima of more than 90 per cent. In addition, the annual temperature range was very low and optimum across the Zone 1. The production potential of small cardamom was low (100-150 kg / ha) over Zone III (Karnataka), where the length of crop growing season was less than 250 days with annual Ima of 70-75 per cent. The annual temperature range was also high, which may be detrimental to cardamom production in the Zone Ill. The Zone II fall under intermediary category (150-200 kg / ha), where the length of crop growing season was more than 250 days with annual Ima varied between 80 and 85 per cent. From the crop weather relationship studies, it was understood that the rainfall from December to May, annual temperature range and temperature range during southwest monsoon could explain up to 78 per cent variability in cardamom production. It was also noticed that cardamom production was high whenever the annual water deficit was low and vice-versa.ThesisItem Open Access Leaf and spadix phenology of coconut (Cocos nucifera L.)(Department of Agricultural Meteorology, College of Horticulture, Vellanikkara, 2004) Shajeesh Jan, P; Prasada Rao, G S L H VThe field experiment entitled "Leaf and spadix phenology of coconut (Cocos nucifera L.) was conducted at Department of Agricultural Meteorology, College of Horticulture, Vellanikkara, during the period from February 2002 - June 2003. The investigations were undertaken with the following objectives such as to understand the seasonal influence on leaf and spadix production and their interval on different cultivars of coconut namely Tiptur Tall, Kuttiadi (WCT), Kasargod (WCT) and Komadan (WCT) including the duration of spadix emergence and on leaf and spadix phenology of coconut. All the four coconut cultivars behaved uniformly with respect to seasons in terms of functional leaves, spathe and female flower production. Nevertheless, they responded differently to different weather variables. However, Tiptur Tall was tolerant to weather aberrations and superior in terms of its floral and yield characters. The study indicated that favourable weather conditions during post monsoon season might have resulted in maximum absorption and translocation of food material during the same season in which maximum number of functional leaves were noticed whereas the rise in temperature, vapour pressure deficit coupled with low rainfall and bright' sunshine hours led to higher leaf shedding during summer. The favourable weather conditions such as optimum soil moisture, maximum temperature and bright sunshine hours during the primordium initiation (29 months prior to the spathe emergence) resulted in maximum spathe emergence during post monsoon. The unfavourable weather conditions such as low rainfall, less rainy days and high maximum temperature coupled with bright sunshine during the primordia initiation stage would have played a major role in low emergence of spathes during the southwest monsoon. The study also indicated that low minimum temperature, and optimum temperature range, wind speed, vapour pressure deficit, evaporation and sunshine hours resulted in maximum spathe duration during winter. The reasons for maximum spadix emergence during summer season can be attributed to the maximum number of spathes present on the crown during winter in which the duration from spathe to spadix was also more. When coconut spathes were exposed to a range of higher atmospheric temperature it may cause for early spadix emergence. In contrast, the number of spathes present on the crown was less during the southwest monsoon and hence the opening of spathe during the ensuing post monsoon was less. The high female flower production during summer can be attributed to the favourable weather prevailed during primordia initiation (32 months prior to the spadix emergence) and ovary development (6-7 months before the spadix emergence,). High maximum temperature, temperature range, sun shine hours and high vapour pressure deficit and prolonged dry spell during the above critical stages caused to the low female flower production during post monsoon season. The number of female flowers produced could be explained up to 99 percent due to weather prevailed during the above two critical stages in the case of Kuttiadi and Kasargod. The relationship between the female flower production and button shedding revealed that when female flower production was high button shedding was also high, while not in the case of Tiptur Tall. It also revealed that button shedding was more in summer 2003 when compared to that of summer 2002. It was attributed to the occurrence of prolonged dry spell from November 2002 to 8th June 2003 when compared to that of summer 2002. In addition to the prolonged dry spell during the above season, the occasional intermittent rains in the form of cloud burst/ summer showers might have caused imbalance in nut setting resulting in immediate fall of buttons. The spathe duration and button shedding in coconut responded positively to the growing degree days. It revealed that that both the above phenological events may respond to thermal regime. Future line of work Such studies, if undertaken for at least five years, will be quite useful in understanding the response of biotic events to weather variations. In addition, the information can be used in crop improvement programmes of coconut.