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ThesisItem Open Access Crop weather relationship in okra(Department of Agricultural Meteorology, College of Horticulture, Vellanikkara, 1999) Kavitha, S; KAU; Kesava Rao, A V RCROP WEATHER RELATIONSllP IN OKRA (Abelmoschus esculentus [L.} Moench), VARIETY 'ARKA ANAMIKA' The experiment was conducted during 1998-1999 at the College of Horticulture, Vellanikkara to find out the crop weather relationships of okra, 'Arka Anamika'. The experiment was laid out in randomised block design with three replications. The treatments consisted of twelve monthly sowing, starting from 21 st April 1998 to 21 st March 1999. Observations on morphological, phenological and yield attributes were recorded during the course of investigation. The daily values of weather elements viz., rainfall, number of rainy days, maximum and minimum surface air temperatures. bright sunshine, mormng and afternoon relative humidity, pan evaporation and wind speed were collected from the Principal Agricultural Meteorological Station, College of Horticulture, Vellanikkara, to work out the crop weather relationships of okra. March, April and September sown crops were significantly superior in terms of fruit yield per plant, number of harvests and crop duration. April sown crop was also superior in plant height, number of nodes on mainstem, and number of primary branches. The fruit yield was significantly associated with the plant height, number of nodes on main stem, number of primary branches, number of harvests and duration of the crop. A multiple regression equation was worked out for predicting fruit yield based on plant characters and it is as follows: Y = 3.08 XI + 11.15 X2 - 210.14 (R2 = 0.94) Where, XI is the duration of the erop in days, X2 is the number of harvests and Y is the yield per plant (g). Based on the association between weather elements and crop yield of okra, a multiple regression equation was worked out and given below: Y = 50.7 XI - 28.69 X2 + 16.11 X3 - 0.058 X4 - 456.29 (R2 = 0.76) Where, Y = yield per plant (g), X, - Minimum temperature (OC) during vegetative phase (6,h to 7th week after sowing), X2 - Maximum temperature (OC) during reproductive phase (6th to 9th week after sowing), X3 - Bright sunshine (h per day) during vegetative phase (4th to 6th week after sowing) and X.4 - Rainfall (mm) during vegetative phase (5th to 6th week after sowing).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 Crop weather relationship studies in bitter gourd(Department of Agricultural Meteorology, College of Horticulture, Vellanikkara, 1996) Lincy Davis, P; KAU; Balakrishna Pillai, PAn experiment was conducted during 1995 – 96 at the College of Horticulture, Vellenikkara to find out the optimum date of sowing and to study the crop – weather relationship in bitter gourd, variety mc –84. The experiment was laid out in randomised black design with 3 replications. The treatments consisted of twelve dates of sowing starting from April 15th, 1995 and ending in March, 15th, 1996. For each and every treatment one control plot was maintained. The biometric observations of the crop growth characters, flowering and yield attributes were taken at different stages of development of the crop. The observations on the incidence of pests and diseases were recorded from the control plots. The observations on weather elements were recorded daily. October sowing was significantly superior to others with regard to number of female flower production, number of fruits, fruit set, fruit length girth, weight and yield. The crop weather relationship studies showed that the temperature range during 45 to 65 DAS and sunshine hours during 40-60 DAS were positively correlated with both total yield and number of female flowers per plant while minimum temperature during 45-60 DAS and mean relative humidity during 45-70 DAS were negatively correlated with both total yield and number of female flowers per plant. Crop sown during September, October and November were free from the attack of Bactrocera cucurbitae (Coq.). While Eudioptes indica (Saund.) occurred throughout the year. Mosaic disease incidence was severe in crops sown during June. But September sown crop was free from diseases.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.ThesisItem Open Access Crops weather relationship in tomato(Department of Agricultural Meteorology, College of Horticulture, Vellanikkara, 1998) Ajithkumar, B; KAU; Lalitha Bai, E KAn experiment was conducted during 1997-98 at the College of Horticulture, vellanikkara to study to influence of date of sowing and levels of nitrogen on the growth and yield of tomato ((Lycopersicon esculentum Mill.) The experiment was laid out in split plot design with three replications. The treatment consisted of nine dates of planting starting from June 15th to February 15th in the main plot and two levels of nitrogen (125 kg N ha-1 and 75 kg N ha-1) in the subplot. Observations on morphological and yield attributes were recorded during the course of investigation. The daily values of various weather elements recorded at the Agromet observatory, college of Horticulture, Vellanikkara were collected to work out the crop weather relationship. February planted crop took less number of days for first flowering, 50 per cent flowering, and had the shortest crop duration. While June planting took maximum number of days for first and 50 per cent flowering. Where as maximum duration of the crop was recorded by planting in October. December planting was significantly superior to other treatments with regard to yield characters. The maximum number of fruits per plant was obtained for December planting followed by October and November planting. Application of 125 kg N ha-1 significantly improved the yield and yield characters as compared to that in 75 kg N ha-1. Higher dose of nitrogen favoured the earlier fruit set, maximum duration of the crop, increase in the number of fruits per plant and thus resulted in enhanced fruit yield. The crop weather relationship studies showed that the morning relative humidity and afternoon relative humidity during the 1st-2nd weeks after planting had a positive effect on the days to first flowering. The minimum temperature (7th-8th week) and morning relative humidity (6th-7th week) were negatively correlated with yield. Days to first flowering showed a negative correlationship with maximum temperature, minimum temperature, temperature range and hours of bright sunshine during the 1st-2nd weeks after planting. The maximum temperature of (31.60C-32.10C) and minimum temperature of 24.10C-24.30C) found to be optimum for early flowering. Wheras minimum temparature of (22.10C-23.30C) and relative humidity during morning hours (70-74%) during 6th and 8th week after planting are optimum for the increase yield. Under Vellanikkara condition, maximum temparature of 30.60C-33.70C, minimum temperature of 22.10C-24.30C, bright sunshine hours of 5.2-10.0, morning relative humidity of 70-86 per cent, afternoon relative humidity of 45-59 per cent is required for optimum crop growth. Based on the experimental data, minimum data set for the validation of tomato model of the IBSNAT has been generated. Result of the present experiment indicate that at Vellanikkara surrdounding tomato can be successfully raised if seedlings are planted in the middle of December. Weather during October and November are also congenial for getting higher yield. The higher dose of nitrogen (125 kg/ha) gave better yield than the recommended dose of nitrogen.ThesisItem Open Access Agroclimatology in crop planning for central zone of Kerala(Department of Agricultural Meteorology, College of Horticulture, Vellanikkara, 1999) Ajith, K; KAU; Kesava Ravo, A V RA study was undertaken to determine weekly index of moisture adequacy (I MA) and water availabi I ity periods for various locations in the central zone of Kerala and to examine the viability of important crops. Daily rainfall data for the period 1978-97 were collected from 26 stations in the central zone. Daily data on maximum and minimum temperature, wind speed, maximum and minimum relative humidity and bright sunshine hours for Kochi, Palakkad, Pattambi and Vellanikkara were collected. Soil data and crop data were also collected for the zone. Mean weekly, monthly, seasonal & annual rainfall and coefficient of variation for all stations were worked out. Spatial variation of mean rainfall and coefficient of variation during the different seasons were studied. Monthly , dependable rainfall at 75 per cent and 90 per cent ' •• vere calculated using the ranking method suggested by Frere and Papov, and its spatial variation over the zone was studied. Initial and conditional probabilities of receiving 30 mm or more rainfall per week following Markov chain model for all the rain gauge stations were worked out and discussed. Water balance elements were computed for the 26 stations following book- keeping method of Thornthwaite. PET was computed following the modified Penman method as suggested by Doorenbos and Pruitt. Annually, the actual evapotranspiration (AET) varied from <400 mm in the eastern region of the zone to >700 mm in the southern part of the zone. The lowest AET ,. of 311 mm was observed at Parambikulam and a highest of 779 mm at Piravom. A I gradual increase of AET can be observed from northern part to southern part. The midland and of the central part of the zone had higher values of water deficit (WD) \ 1 '~L t '. compared to the northern and southern parts i.e., more than 1300 mm. Parambikulam had highest value for WD i.e., 1606 mm. Almost all the coastal region and midland of the northern and southern parts were found to have lesser WD value « 1300 mm.) Water surplus (WS) was high in the midland and coastal areas of the zone. The highest value of WS, 913 mm was observed at Wadakkancherry followed by Kunnamkulam (614 mm) both in the coastal region. Almost all stations in the coastal region were found to have higher values ofWS, i.e., more than 400 mm except a small patch around Kochi. Water availability periods were identified comparing the AET and PET. It was found that water availability periods followed the same pattern for most of the stations in the central zone. It was characterised by a 1 st sub humid period followed by a humid period and a 2nd subhumid period. The highest number of moist days was recorded at Piravom (203) followed by Aluva and Perumbavoor(188). At this station the humid period extended for 170 days which is also the highest value compared to all other stations. The least number of moist days was observed at Parambikulam (82). At this station there is a break in the humid period which gave way to a sub humid period. Most of the stations have total number of moist days more than 150. Generally, the water availability period starts in the 2nd week of June and extends up to 3rd week of November. " The cropping system of the central zone of Kerala was analysed and it was found that the cropping patterns fall under three major categories (1) mainly paddy (2) mainly coconut and (3) plantations other than coconut. The viability of these cropping patterns based on water availability periods and soil information are discussed.