Anand

An Agroclimatic atlas of Gujarat state was published. Rainfall data from 375 gauges, weather data from 35 meteorological observatories were analysed and spatial and temporal variation in different agroclimatic parameters were depicted. Time series analysis of rainfall for the different districts was also included.

LASPEX experiments conducted in Sabarmathi basin

Initial and conditional rainfall probabilities at different threshold values were worked out for 31 stations of Middle Gujarat Agroclimatic zone.

Rainfall data of five districts in the Saurashtra region were analysed in relation to groundnut productivity. Threshold values of rainfall for maximum productivity were determined.

For studying crop-weather relationships field experiments were conducted for five years with 3 varieties, and two row spacings. Thermal variables such as maximum and minimum temperatures, bright sunshine hours and evapotranspiration were found to have favourable effect on pod yield. Phenophasic-weather element correlations (at different growth stages) with pod yield showed weather during emergence to 50 per cent pegging phase to be the most significant factor.

Energy balance components were measured and derived over pigeonpea crop which revealed presence of advective conditions during the 50% podding stage where PAR absorption and leaf area index were also maximum. The magnitude of sensible heat at this stage in relation to net radiant energy would be the agroclimatic factor determining final yield.

Water production functions for wheat were determined. Higer water use efficiency and maximum yield were obtained for crop sown in mid-November with application of 271mm of water.

For simulation of crop growth, PNUTGRO (for groundnut, PLANTGRO and BRASSICA models (for mustard) were used and tested with field observations. The models in general predicted phenological events within 2-day's deviation. For the different sowing dates, final yields deviated from the observed ones. The models need modification in certain sub-routines for adopting them to local conditions.

Disease index for Powdery mildew over mustard crop was found to be positively correlated with evaporation, sunshine duration, wind speed and maximum temperature while relative humidity showed a negative correlation. A rgression equation was developed to predict the disease index using mean temperature and crop age.