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Anand Agricultural University, Anand
Anand Agricultural University (AAU) was established in 2004 at Anand with the support of the Government of Gujarat, Act No.(Guj 5 of 2004) dated April 29, 2004. Caved out of the erstwhile Gujarat Agricultural University (GAU), the dream institution of Sardar Vallabhbhai Patel and Dr. K. M. Munshi, the AAU was set up to provide support to the farming community in three facets namely education, research and extension activities in Agriculture, Horticulture Engineering, product Processing and Home Science. At present there seven Colleges, seventeen Research Centers and six Extension Education Institute working in nine districts of Gujarat namely Ahmedabad, Anand, Dahod, Kheda, Panchmahal, Vadodara, Mahisagar, Botad and Chhotaudepur
AAU's activities have expanded to span newer commodity sectors such as soil health card, bio-diesel, medicinal plants apart from the mandatory ones like rice, maize, tobacco, vegetable crops, fruit crops, forage crops, animal breeding, nutrition and dairy products etc. the core of AAU's operating philosophy however, continues to create the partnership between the rural people and committed academic as the basic for sustainable rural development. In pursuing its various programmes AAU's overall mission is to promote sustainable growth and economic independence in rural society. AAU aims to do this through education, research and extension education. Thus, AAU works towards the empowerment of the farmers.
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ThesisItem Open Access ESTIMATING WHEAT YIELDS IN GUJARAT USING WTGROWS AND INFOCROP MODELS(AAU, Anand, 2003) AKULA, BABY; Shekh, A. M.Crop simulation models are valuable tools to researchers to help them to understand the influence of climatic variables on crop productivity. The model estimated yields are handy to the agencies in government, trade and industry for planning about distribution, storage, processing, export or import of crop produce. Yield estimates by the models are also useful in taking timely policy decisions on fixing levy prices, because the estimates of the yield are available well in advance of the actual harvesting of the crop. Hence, a two-pronged approach was followed to estimate wheat yields in Gujarat, with the help of WTGROWS and InfoCrop simulation models. Initially both the models were calibrated and validated under Anand conditions through field experiment laid out in a strip plot design with three replications during rabi season of the years 2000 and 2001. Tliree dates of sowing were assigned as a main plot treatment with four irrigation regimes as sub plot treatments. Consistently higher yields were realised in case of the second date of sowing (15* Nov) during both the years although the yield differences were not statistically significant. Relatively more yields were realised in 2000 than those realised in 2001 and this was due to prevalence of favourable low temperatures during 50-90 DAS - a period that corresponded with anthesis to dough stage in conjunction with intermittent cold spells from 70-75 DAS corresponding with soft dough phase in the former year. In contrast to what was observed in case of yields in relation to the dates of sowing, yield data due to different irrigation treatments showed significant differences among them. Three irrigations gave significantly the lowest yield as compared with yields realised through any other irrigation treatment. The lowest yields realised in the treatment involving three irrigations were due to prevalence of moisture stress during tillering and flowering. Paradoxically, six irrigations despite not missing any important physiological stage, did not record significantly higher yield in comparison with yield in response to five irrigations. This was on account of the fact that, luxurious vegetative growth in the former case had caused lodging, as the prevailing wind speed was high. Different test criteria were followed to validate the performance of the models. Besides, error per cent was also calculated in all the different treatments to express the deviation in simulated values from those observed. Close scatter of simulated yield and total dry matter and respective measured values around the regression line and 1:1 line in case of both the models indicated good agreement between them. Both the models exhibited their robustness in predicting yields by explaining more than 90 per cent of variation in yield and total dry matter on an overall basis. However, there still remains some scope for improvement of the models in accounting for the loss due to lodging. The estimated RMSE for yield by WTGROWS was 318 kg ha-1, while that for yield by InfoCrop was 360 kg ha-1. Among the different dates of sowing, error per cent was relatively low in the treatments of the second date of sowing when compared with that for other dates. Both the models displayed decrease in error per cent with increase in irrigation levels. Underestimation of the simulated yield was more when the number of irrigations was less [three (I1) and four (I2)] when compared with that for more irrigations [five (I3) and six (I4)]. The underestimation was relatively more in case of InfoCrop, than that in case of WTGROWS. The performance of the models could be adjudged with the index of agreement (D), which was relatively high for WTGROWS (D= 0.97) than that for InfoCrop (D=0.95) in terms of yield. The models were also observed to perform in a similar way in terms of their response to the treatments in case of total dry matter, phenology and LAI also. The days to anthesis and maturity were simulated with less accuracy by both the models as compared to that of yield. Anthesis by WTGROWS explained more variance (R2=0.82) than that explained by InfoCrop (R2=0.75). The performance of these models in explaining the variance due to days to maturity was reverse of what was observed in case of anthesis. The highest and the .lowest ET were observed in case of the treatments of D2I4 and Dili, respectively. WTGROWS also showed similar pattern. Relatively higher proportion of MBE as compared to that of MAE during both the years in terms of ET as simulated by WTGROWS revealed under- prediction of ET by the model. Nonetheless, the error per cent did not cross the limit of -15 per cent during both the seasons except in case of Dill (-15.77%). Both the models expressed sensitivity to weather parameters viz., temperature, radiation and CO2 levels under both potential and stressed test conditions. But, the magnitude of change from the respective base yields in case of both the models was more to temperature under stressed conditions. However, the magnitude of response was more in case of WTGROWS than that in case of InfoCrop on overall basis except in case of radiation under stressed conditions where InfoCrop exhibited relatively more sensitivity. Linear response to TTVG, POTGWT, GNODMA, NSOILI, WLSTI was observed in case of both the models. The sensitivity was relatively more in case of WTGROWS than in case of InfoCrop. Moreover, InfoCrop exhibited linear response to RGRPOT and SLAVAR also. Statistical analysis of the historical actual wheat yield data of the state revealed that the average actual yield for the state as a whole was 2.5 t ha-1. Out of the ten districts selected to understand the temporal and spatial variability in wheat production levels and further to estimate yield gap through linking the model results with GIS, only Junagadh, Banaskantha and Bhavnagar exhibited significant positive linear trend at an average increase rate of 66, 31 and 25 kg ha-1 yr-1, respectively. Majority of the other districts failed to exhibit any discernible linear trend. However, Mehsana was found to be the second potential wheat producer of the state after Junagadh. The estimated average district potential yield by the models was 5.9 t ha-1 on overall bases. This is 2.36 times higher than the average actual state yield and is due to favourable thermal regimes as it was evident under Anand conditions where the estimated TTVG explained 87 per cent of variation in the potential yield and indicated significant linear positive trend. Similar reasoning holds good for higher potential yields in other districts. The attainable yields were estimated by imposing the management constraint of delayed sowing by twenty days from the optimum time (15thNov). The attainable wheat yields were found to decrease in all the districts irrespective of the agro climatic zone. The estimated attainable yield for the state as whole was 4.8 t ha-1 on the basis of the ten districts considered in the study. The average sowing yield gap between potential and attainable yield varied from 863 to 1205 kg ha-1 Reduction in yield due to delayed sowing was highest in the districts of Saurashtra which was followed in this respect by middle Gujarat, north Gujarat and south Saurashtra in sequence. The quantity of reduction in succession in these agro climatic zones was to the tune of 60, 59, 49 and 44 kg ha-1 per day delay in sowing, respectively.ThesisItem Open Access RESPONSE OF CAULIFLOWER (Brassica oleracea var. botrytis) TO WEATHER WITH VARYING IRRIGATION SCHEDULES AND TESTING OF VEGETABLE MODEL FOR MIDDLE GUJARAT AGROCLIMATIC ZONE(AAU, Anand, 2005) B., AJITHKUMAR; SAVANI, M. B.Cauliflower (Brassica oleraceae var. botrytis) is one of the most popular winter vegetable crops grown in India. The cultivation of the crop has been found to be highly remunerative under irrigated condition during rabi season and hence gaining popularity among the vegetable growing farmers of Gujarat state. The crop requires certain cardinal levels of various factors of environment like air and soil temperature, quality, intensity and duration of radiation, humidity of air and soil etc for its optimum physiological functioning. Since, the effects of weather on curd yield are complex, deeper and clear understanding of how the climatic factors affect the growth and yield of cauliflower. A field experiment during rabi seasons of the years 2002-03 and 2003-04 was therefore laid out in a split plot design with three replications. The three dates of planting were assigned as main plot treatments, three irrigation regimes as sub plot and two spacing as sub- sub plot treatments. The results obtained during the course of study revealed that the weather had played a significant role in deciding the yield of cauliflower. However, the weather variables had affected the crop growth and yield differently in different phenophases during its growing period. The results regarding the curd yield as well as the biomass of cauliflower as influenced by the different dates of planting showed that Di planted crop produced significantly higher curd yield as well as biomass. The favorable weather conditions in D1 planted crop influenced the entire physiology of the crop culminating into the higher yield. D3 planted crop which encountered unfavourable weather conditions like the high temperature and high solar radiation during the curd maturity phase resulted in leafy and small curds. Irrigation scheduled through IW / CPE = 1.O and spacing of 60 cm x 45 cm proved the best. The correlation and regression studies between the weather elements and the time taken for completion of the phenophases revealed that certain weather parameters significantly correlated with the time taken for completion of the corresponding phenophase. The number of days taken to juvenile phase was negatively and significantly correlated with the mean values of the T max, T min, Tmean, RH1, VP1, VP mean, BSS and EP. The maximum, minimum and mean temperatures were also negatively and significantly correlated with number of days during the curd induction phase and curd maturity phase. Regression models were developed for prediction of phenophases using different weather variables. The correlations were worked out between the days taken to attain a specific phenophase and agrometeorological indices encountered to complete the phenophase were found positive and significant. The regression model was developed for the prediction of the number of days required for completion of different phenophases on the basis of agrometeorological indices. GDD and PTU yielded the lowest coefficients of variation and as such they were considered as better heat unit indices for prediction of the cauliflower yield during the rabi season for the middles Gujarat agro climatic conditions. The results on germination studies revealed that the number of days taken to reach 80 per cent germination was lower in the first year than that in the second year. The mean air temperature ranged from 28.9 to 31.8°C and the soil temperature from 30.5°C to 32.0°C which had favoured the germination of the seeds. The LAI values revealed that the development of the leaf area remained slow during the early vegetative growth period (juvenile phase) upto 30-45 days after planting and thereafter, increased sharply with the advancement of the crop age during both the years in all the dates of planting. The heat use efficiency increased with advancement of the age of the crop. There was a gradual decrease in k value with the advancement of the crop to maturity. The rate of crop growth was low in the first 31-45 days after planting and thereafter increased with crop age.ThesisItem Open Access RADIATION REGIME OVER ROW ORIENTATION IN WINTER WHEAT (Triticum aestivum L.)(AAU, Anand, 2004) LUNAGARIYA, MANOJKUMAR MAVJIBHAI; Shekh, A. M.A field experiment was conducted during the rabi season of 2003-2004 at Anand. The experiment was laid out in Split Plot Design with the two dates of sowing as main plot and four treatment combinations of two row orientation and two row spacing as sub-plots, replicated four times. The objective was to study solar radiation regime with respect to the row orientation, row spacing and leaf geometrical parameters for Wheat crop (cv. GW- 496). The experiment was planned with the objectives to determine the influence of the treatments on the RUE, Extinction Coefficient (k), Direct beam radiation interception, soil surface temperature and soil moisture lost/evapotranspiration (as influenced by radiation penetration between rows). Comparison of the season encountered by the crop during the experimental period with that normally found in the region was made by comparing the seasonal values of different weather parameters with their normal for Anand. The nonsignificant differences in respect of each of the weather parameters established that the experimental season was identical to the normal one. Hence these results could be applicable to any normal wheat growing season around Anand region. The experimental findings obtained during the course of the present investigation revealed that the highest interception was recorded during the morning hours and there was negligible difference among the treatments in this respect. The difference in the interception was higher during noon time and narrow NS rows intercepted higher PAR (0.92). Wide NS rows and wide EW rows had higher solar radiation interception than that narrow EW rows at noon hours. The seasonal average of the fraction F indicated more or less identical results that representing different treatments, narrow NS oriented row had highest F value i.e.0.86 and while in narrow EW rows had the poorest value (0.77). There was low RUE in early growth stages because more solar energy was used up being incident on the soil surface rather than on the plants due to inadequate development of plant canopy. The RUE showed maximum value at booting stage. There was no significant difference in the RUE among the treatments and also among interactions. The difference in the RUE was found negligible. Slightly high RUE was found in the widely spaced EW rows during in second sowing (i.e.2.07 g MJm-2) as compared to the general mean (i.e.2.01 g MJm-2). The lowest RUE was observed in wider NW rows (i.e. 1.96 g MJm-2 and 1.97 g MJm-2 for respective sowing times). There was no statistically significant difference among HI values corresponding to different treatments revealed that there was no difference in fraction of radiant energy used for grain biomass. High averaged LAI was recorded in narrow NS rows during both sowing dates (3.26 and 3.7, in respective sowing dates). Wide NS rows (2.67 and 3.38, in respective sowing dates) succeeded this treatment. The EW rows produced lower LAI. The NS rows (narrow and wide) did not show much fluctuation in the values of k (extinction coefficient), while EW rows (narrow and wide) showed comparatively more fluctuations, indicating the changes in canopy structure. The average value of leaf orientation over the entire study indicated that leaves usually preferred N (16.6 %), S (16.1%) and W (13.2%) direction. General results showed the leaves were randomly oriented with different times. The seasonal average of direct beam interception fraction (I/I0) indicated that the in general, highest direct beam interception occurred on the first leaf and lowest on the second leaf while third leaf had intermediate direct beam interception. Maximum average interception fraction was 0.63 over the third leaf and minimum (0.22) over second leaf of the wider NS rows during second sowing. While, in case of the narrow NS rows of the first sowing, second leaf had high interception with 0.61 fraction, first leaf had value 0.24 and third leaf had fraction 0.41. Except these two. values for NS oriented treatments the leaves of the other treatments showed intermediate direct beam interception fraction ranging from 0.31 to 0.51 over the entire season. Soil surface temperature was observed to be slightly high at morning hours (1000 h) in the wider EW rows during both the sowings. Those for narrow EW rows followed these values. During noon time (1300 h), wide NS rows had higher soil surface temperature than respectively that for other treatments. In afternoon, the soil surface temperature did not show much difference among treatments. The difference in the temperature was considered as the function of the radiation penetration in the rows. Wide NS rows had higher evapotranspiration, in general after early growth period. Other treatments showed no distinct pattern in this respect. The moisture loss pattern had almost parallel trends for narrow and wide rows in particular orientation. This indicated that there was influence of spacing on evapotranspiration. The results revealed that NS rows and wider spacing had high radiation penetration.ThesisItem Open Access POTATO CROP GROWTH AND YIELD PREDICTION USING SPECTRAL INDICES AND METEOROLOGICAL PARAMETERS(AAU, Anand, 2000) RAO, GATTINENI SRINIVASA; Shekh, A. M.Potato {Solarium tuberosum L.) is one of the four major crops of the World after rice, wheat and maize. It is one of the World's most nutritious plant sources of food for human consumption. Potato can be raised in wide range of climatic conditions. Plant growth and tuber production are markedly influenced by environmental conditions particularly temperature and radiation. Response of a plant to radiation in different spectra indicates the status of plant stand. This information can be explored for advance estimation of crop yield through satellite imagery. However, before it could made available, one has to identify the significant spectral bands contributing to the yield. Advanced estimation of crop production for the major food crops is considered essential for taking judicious decisions on procurement, storage, pricing and marketing of these commodities, and also for strengthening the public distribution system. The development of crop yield prediction models is necessary for assessing the production of a particular crop in a region. An experiment on potato crop was conducted with the objectives to develop the models, which would predict the final tuber yield using spectral indices and meteorological parameters, to study the variation of spectral characteristics with the change of growth parameters, to develop the interrelationships among growth parameters and vegetation indices, to develop the model that could predict different growth parameters using spectral indices and meteorological parameters and to study the crop weather interrelationships between the potato growth at various phases of development and the meteorological factors. The field experiments were conducted on potato cv. Kufri Badshah, JL-4780; during the rabi seasons of 1996-97 and 1997-98 in split plot design with three dates of sowing (viz., D1: 25th October, D2: 15th November and D3: 6th December) as main plots and two irrigation regimes (viz., I1: farmers' method of irrigation and I2: GAU recommended method of irrigation) as sub-plots, replicated six times. The results obtained in the present investigation revealed that the planting date had a significant effect on attainment of different phenophases, crop growth and tuber yields. But the irrigation regimes adopted for the present study had non-significant effect on the final tuber yield. The crop sown during the 3rd week of November recorded significantly higher yields (i.e., 34.95 t ha-1) than that grown either earlier (i.e., October, 20.03 t ha-1) or later (i.e., December, 31.84 t ha-1). It was observed that there was a progressive delay in the number of days to attain 50% emergence with early planting due to higher temperatures, i.e., > 22 °C. The analysis of meteorological parameters vs. phenological phases and yield revealed that the optimum mean air temperature for 50 % emergence was 21.5 °C. While, the optimum soil temperature at 5 cm depth for the same phase was 24.4 °C. The optimum mean air temperature and soil temperature at 5 cm depth for tuber initiation were respectively 19.9 °C and 22 °C. For tuber development, bulking and physiological maturity, the mean air temperatures were respectively 20.6, 18.3 and 18.9 °C. The optimum soil temperatures at 5 cm depth for the same phases were 22.3, 20 and 21.2 °C, respectively. The Huctuations in bright sunshine hours in the November date of sowing were less than those for the other two date of sowing,, during both the years. This contributed to the higher final tuber yields in the November sown crop. In general, the optimum range of different meteorological parameters for higher yields were 18 to 22 °C, 20 to 24.4 °C and 7.9 to 9.9 h for mean air temperature, soil temperature at 5 cm depth and bright hours of sunshine, respectively. The results of the correlation studies conducted between days taken to complete different phenophases and accumulated growing degree days (AGDD) showed a very strong positive significant relationship (r = 0.98) between them and the regression model developed to predict the attainment of different phenophases performed fairly accurately (R2 = 0.97). The crop sown on 15th November, recorded higher leaf area index (i.e., LAI = 5.19) and the corresponding crop growth rate was 24.9 g m-2day-1, which contributed to the achievement of higher tuber yields of 38.12 t ha-1 The model developed for prediction of maximum LAI using AGDD, predicted LAI with the coefficient of determination of 0.80. The average absorbed photosynthetically active radiation (APAR) use efficiency obtained for the present investigation was 2.39 g MJ-1, while its range was from 1.84 to 3.45 g MJ-1. The range of extinction coefficient (k) values obtained was 0.63 to 0.81 with an average value of 0.73. The correlation studies between APAR use efficiency and meteorological parameters revealed that the parameters maximum, minimum, mean temperatures and soil temperature at 5 cm depth had a significant negative interaction with RUE. The spectral indices viz., ratio vegetation index (RVI) and normalized difference vegetation index (NDVI), increased with crop growth irrespective of the treatment and was highest at maximum LAI. The highest values of RVI (i.e., 8.17) and NDVI (i.e., 0.82) were observed, in case of D2 sown crop. The results revealed that the saturation of spectral indices occurred at LAI values between 4.5 and 5. The regression models developed to predict the LAI using spectral data revealed that the NDVI model predicted with better accuracy (R2 = 0.94) compared with the prediction by RVI model (R2 = 0.88). But, for the prediction of dry matter accumulation both the RVI (R2 = 0.99) as well as NDVI (R2 = 0.96) models predicted the dry matter with better accuracy. The regression models developed for dry matter prediction using evapotranspiration (ET) and spectral indices, predicted the dry matter accumulation with the coefficient of determination of 98 and 97 % by using RVI and NDVI data, respectively. The regression models developed to predict LAI using APAR and spectral indices, predicted the LAI with the coefficient of determination of, respectively 93 and 94 % using RVI and NDVI data. The correlation studies conducted between spectral indices and tuber yield, APAR and dry matter revealed that there did exist a positive association between them. The regression models developed to predict the tuber yield on the basis of spectral indices and LAI as the independent variable, predicted tuber yield with the coefficients of determination of 53 and 59 % by inclusion RVI and NDVI data, respectively. The predictions held good, by using LAI and spectral data, at 70, 85 and 95 days after sowing. As against this, the regression models developed to predict tuber yield by using APAR and dry matter as independent variables along with spectral indices predicted the tuber yield with the coefficient of determination of 67 and 78 % by using RVI and NDVI data, respectively. In this regard, the best predictions could be obtained by using APAR, dry matter and RVI data at 35, 55 and 65 days after sowing and by using the data of APAR, dry matter and NDVI at 35 and 70 days after sowing.ThesisItem Open Access CROP WEATHER RELATIONSHIP OF ONION (Allium cepa L.)(AAU, Anand, 2001) CHAUHAN, VIKRAM SINGH; Savani, M. B.An experiment was conducted during the rabi season of the year 1998-99 at Anand to study the crop weather relationship of onion. The field experiment was laid out in split plot design with four replications. The treatments were three dates of transplanting, two plant spacing and three irrigation levels. Plant height, number of leaves per plant, fresh, weight of bulb, bulb diameter, total soluble solids (TSS) and bulb yield increased with earlier transplanting and bolting, doubling decreased with late transplanting and bulb dry weight was increased with late transplanting of the crop. Plant height, number of leaves, fresh weight of bulb, bulb diameter, TSS and bulb dry weight were higher with wider spacing whereas bolting, doubling and neck diameter decreased with closer spacing and bulb yield was increased with narrow spacing of the crop. Higher IW/CPE ratio increased plant height, number of leaves, fresh weight of bulb, bulb diameter, TSS bulb dry weight and bulb yield whereas lower IW/CPE ratio decreased bolting, doubling and neck diameter of the bulb. The crop required nearly 2270 GDD, 22000 PTU, 13600 HTU and 500 mm of water. Water use efficiency varied with the variation in the irrigation regimes and ranged between 30.25 Kg ha-1 mm-1 and 169.57 Kg ha-1 mm-1.ThesisItem Open Access Rice yield prediction using Crop Growth Simulation and Agrometeorological models in Gujarat(AAU, Anand, 2007) Vikram Singh Chauhan; Dr. A.M. ShekhAmong the various production commodities of basic importance, agricultural production is the one which is subjected to wide and irregular fluctuations of output. The importance of timely and reliable prediction of yield of principal crops need to be emphasized for the country like India where, the economy is mainly dependent on rainfed agriculture. Various yield prediction models are very much useful to the government agencies, trade and industry for planning about the distribution, storage, processing, and export/import of crop produce besides taking timely policy decisions on fixing levy prices as they provide accurate advance estimation of yields. Besides this, these models have facilitated identification of production constraints and for assisting in agro-technology transfer. The present study was undertaken to predict the rice yield using crop simulation models and to develop an appropriate agrometeorological model for prediction of rice yield in Gujarat. Crop growth simulation models viz. DSSAT and WOFOST were calibrated and validated under Gujarat conditions. Suitabl agrometeorological model for predicting the yield of rice was also developed by using combined effects of different weather parameters viz. rainfall, bright sunshine hours, maximum and minimum temperature and morning and afternoon relative humidity on rice yield. For the present investigation the major rice growing districts of Gujarat viz., Ahmedabad, Baroda, Bulsar, Kheda, Panchmahal, Sabarkantha and Surat were considered. The simulation results of DSSAT model for different districts revealed that the performance of the model for grain yield for all the districts was found highly significant with coefficient of determination values of 98.3% and 95.6% during the years 2004 and 2005 respectively. Various test criteria were applied to validate the performance of the model. The simulation performance of grain yield was found better in 2004 than in 2005. The error per cent during the year 2004 was 9.9% and it was 10.3% in 2005. The average error as computed by MAE was 139.3 and 135.6 with 173.3 and 186.4 RMSE during 2004 and 2005 respectively. The respective MBE was found to be 89.0 and -94.7 and index of agreement was 0.98 and 0.97. Sensitivity study of DSSAT revealed that 3°C elevation in mean ambient temperature decreased the yield by 4 to 41%. The 3°C down scaled ambient temperature increased the yield by 7 to 76%. The solar radiation increase from 1 to 3 MJm-2 day-1 resulted in 2 to 26% yield increase. In case 3 MJm-2 day-1 reduction in solar radiation, 1 to 42% decrease in yield was observed. Elevation of 300 ppm in CO2 concentration over its base value increased yield by 4 to 29%. The simulation results of WOFOST model simulation in both the years for different districts revealed that the simulated values of grain yield were found in perfect agreement with corresponding observed yield. Error per cent of WOFOST was 6.83% and 7.34% during 2004 and 2005 respectively. The coefficient of determination was 99.6% and 97.1%; MAE was 93.85 and 91.14, RMSE was 116.98 and 134.60 and MBE was found to be 50.14 and -66.57, respectively during the year 2004 and 2005. Three approaches using original observed weather variables (1) weekwise, (2) stagewise and (3) periodwise average weather vaiables and two approaches using generated weather variables (1) week number as weight and (2) correlation coefficient as weight were used for fitting of the agrometeorological models. Approaches using shorter interval i.e. weekly weather variables either original or generated were found superior to the approaches using longer period averaged weather variables i.e. stagewise and periodwise approaches. The results revealed that the effects of all the weather variables in relation to their quantum and direction differed over the approaches. However, they were found important for prediction point of view in rice productivity. The effect of weather variables also differed within the crop stage and period, indicating that small interval of crop period results in significantly higher R2 value and thereby minimizes the error of predicting the rice yield. Different approaches were found superior over others in different districts. In Ahmedabad district week number as weight approach provided suitable yield prediction model, eight week before expected harvest which explained > 75% variation in productivity. The 12 week model fitted with week number as weight approach is recommended as rice yield prediction model for Ahmedabad district Y = 6304.22 + 3.80 RHE1 – 0.69 RHM2 + 0.26 (RF*RHE)0 – 2.37 (MINT*RHE)0 + 4.36 (MAXT*RHM)2 (Adjusted R2 = 90.6%) Weekwise approach provided suitable yield prediction model in Baroda district, 8 weeks before harvest which explained > 75% variability. The 12 week model fitted with weekwise approach is recommended as rice yield prediction model for Baroda district Y = – 5050.94 – 0.33 RF2 + 19.06 BSS6 + 37.45 RHM9 – 42.51 BSS10 + 178.41 BSS11 + 24.46 RHM11 (Adjusted R2 = 99.4%) The 18 week model fitted with weekwise approach which provided earlier rice yield prediction (2 weeks before harvest) and explained > 75% variability is recommended as rice yield prediction model for Bulsar district Y = 5788.42 – 23.63 BSS3 – 0.15 RF3 – 69.95 MAXT5 + 59.49 MINT5 – 86.85 BSS6 + 106.21 BSS7 + 2.47 RF7 +103.57 MAXT8 – 33.49 BSS9 + 25.88 BSS11 + 3.73 RF11 – 0.84 RF12 – 170.01 MAXT13 – 70.32 MINT13 – 106.46 BSS14 – 41.87 RHE14 + 0.60 RF16 + 41.80 RHM17 (Adjusted R2 = 99.8%) The 20 week model fitted with weekwise approach which explained > 75% variability is recommended as rice yield prediction model for Kheda district Y = 8682.13 + 317.72 MINT10 + 12.87 RHE10 – 202.97 MINT12 – 59.17 MAXT18 – 79.21 BSS19 – 32.92 RHM19 (Adjusted R2 = 99.8%) The 12 week model fitted with weekwise approach which provided earlier prediction of the rice yield (8 weeks before harvest) and explained > 75% variability is recommended as rice yield prediction model for Panchmahal district Y = 8881.23 – 105.44 BSS2 + 105.02 MAXT2 – 164.14 MINT2 – 8.90 RHE2 – 54.41 RHM7 + 2.78 RF8 – 80.16 MINT10 (Adjusted R2 = 96.0%) The 14 week model which provided earlier prediction (6 weeks before harvest) and explained > 75% variability is recommended rice yield prediction model for Sabarkantha district Y = – 1075.72 + 37.25 RHM1 + 2.68 RHM3 + 8.99 RHE4 + 28.55 RHM5 – 34.24 RHM6 – 6.40 RHE10 – 59.89 MAXT11 + 68.84 MAXT13 (Adjusted R2 = 99.8%) The 20 week model fitted with weekwise approach which explained > 75% variability is recommended as rice yield prediction model for Surat district Y = 2851.46 + 72.40 MINT1 + 57.63 MAXT4 – 17.24 MAXT5 -0.06 RF8 – 2.83 RHM9 – 1.38 RF11 – 18.61 MINT16 – 2.75 RF18 – 1.66 RF19 – 89.51 MAXT20 – 6.24 RHE20 (Adjusted R2 = 99.8%) The developed agrometeorological models were equally comparable to the crop growth simulation models viz. DSSAT and WOFOST in all the districts except in Baroda district where the performance of WOFOST and DSSAT respectively was found superior to the developed agrometeorological model. The average performance of the models was adept in yield prediction for all the districts. The percent deviation for DSSAT was ±0.9 to ±9.9%, for WOFOST from ±0.2 to ±6.1 and for agrometeorological model it was ±0.1 to ±16.8%. The developed agrometeorological models could efficiently predict the rice yield upto 8 weeks i.e. two months before the actual harvest of the crop with very high accuracy (>90%). Thus these developed agrometeorological models can help the government and various other agencies to take appropriate steps is case of ensuing scarcity or glut situation. The DSSAT and WOFOST also predicted the rice yield in reasonable limit with additional advantage to project yield fluctuation with reasonable accuracy in fluctuating weather particularly temperature, solar radiation and CO2 concentration.ThesisItem Open Access SIMULATION MODELLING OF WHEAT (cv. GW - 496) YIELD USING CERES-WHEAT MODEL IN VARIED ENVIRONMENTAL AND MOISTURE REGIMES OF MIDDLE GUJARAT AGRO-CLIMATIC REGION(Anand Agricultural University, Anand, 2004) H. R. PATEL; Dr. A. M. ShekhIn order to sustain the higher production and minimize the degradation of crop production by varied environmental conditions, an understanding of crop growth in relation to varying resource input and agro-environments is required for management options. Improved production technology at the farm level is the most crucial starting point for future improvement of productivity of wheat by employing and adapting suitable crop growth simulation models. In addition to this, the use of crop growth simulation models comes handy to the government agencies, trade and industry and for planning about the distribution, storage, processing, and export/importThesisItem Open Access CROP-WEATHER RELATIONSHIP OF RABI MAIZE (Zea mays L.) GM-3 IN DIFFERENT METHODS OF SCHEDULING OF IRRIGATION UNDER MIDDLE GUJARAT CONDITION(Anand Agricultural University, Anand, 2005) Ambarish Paikaray; Dr. M.B. SavaniA field experiment was conducted during the rabi season of 2002-2003 at Anand. The experiment was laid out in split plot design with the four irrigation scheduling as main plots and five treatment combinations of level of nitrogen doses as sub-plots. The objective was to study the crop-weather relationship and energy use efficiencies for rabi-maize (cv. GM-3). The experiment was planned with the objectives to determine the influence of the treatments on the RUE, Extinction Coefficient (K), soil surface temperature and soil moisture lost/evapotranspirationThesisItem Open Access STUDY OF CROP WEATHER RELATIONSHIP AND EVALUATION OF THE CERES – PEARL MILLET MODEL UNDER RAINFED CONDITION AT ANAND(Anand Agricultural University, Anand, 2006) V.R.Parmar; Dr. VYAS PANDEYPearl millet is an important cereal crop of rainfed area of India. The cultivar of the pearl millet crop has been found to be highly remunerative under kharif season and hence gaining popularity among the cereal - growing farmers of Gujarat state. Crops require certain cardinal levels of various factor of environment like air temperature, intensity and duration of radiation, humidity of air and soil moisture etc. for optimum physiological functioning. Since, the effects of weather on grain yield and fodder yield are complex. It will need the deeper and clear understanding of the climatic factors affecting the growth and yield of pearl millet. The field experiment during kharif season of year 2004 was laid out in a split plot design with four replications. The three dates of sowings were assigned as main plot treatment, four spacings as sub plot treatments.