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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 CROP WEATHER RELATIONSHIPS AND POPULATION DYNAMICS OF Helicoverpa armigera IN TWO PIGEON PEA (Cajanus cajan L.) CULTIVARS IN MIDDLE GUJARAT AGROCLIMATIC REGION(AAU, Anand, 1996) RAVIPATI, MAHENDRA KUMAR; Savani, M. B.Pigeonpea [Cajanus cajan L.) is one of the major grain legume crop in tropical and sub - tropical regions of India and grown mainly as rainfed crop. The crop is characterised as drought resistant and the productivity is different in different environments. Since the effects of weather on yield are complex, the deep and clear understanding of the effect of weather parameters on the growth and development of pigeonpea is necessary. An experiment was conducted during the Kharif season of the, year 1994 at Anand to study the crop-weather relationship and crop-weather-pest dynamics in two cvs.BDN-2 and GT-100 of pigeonpea. The field experiment was laid out in split plot design with four replications. The treatments comprised of two irrigation levels, two plant protection levels, two varieties, and three dates of sowing. The results obtained during the course of investigation revealed that weather played significant role in growth, development and yield of pigeonpea. The variations in days taken to complete the different phenophases among the different dates of sowing were attributed due to the variations in temperature and photoperiod. The number of days required for the completion of any phenophase was declined with increase in the temperature and photoperiod. The yield and yield attributes were significantly influenced by irrigation and dates of sowing. The grain yield, biomass, and number of pods per plant were observed more in D1 than in D2, and D3. Grain yield, biomass, and number of pods per plant declined with the application of irrigation. The irrigated crop puts up more biomass initially but it was declined considerably than in unirrigated crop in the later phases due to heavy attack of the larvae of Helicoverpa. The different agrometeorological indices like GDD, PTU and HTU has positive and significant correlation with days taken for the completion of the different phenopases, eccept for the phenophase P4. The thermal time (GDD) has highly significant correlations with days taken for different phenophases. Functional relations were developed to predict the number of days required for different phenophases in both the cultivars BDN-2 and GT-100. The leaf area index (LAI) and crop growth rate (CGR) were found to be influenced by irrigation and sowing time. The crop sown in D1 maintained more LAI and CGR in both the cultivars, compared to D2 and D3, The decline in the values of LAI and CGR during flowering phase in both the cultivars was due to heavy infestation of Helicoverpa. The radiation use efficiency (RUE), on seasonal basis was found to be high in rainfed crop compared to irrigated crop. The RUE was high in D1 sown crop, and was declined in the delayed sowings. The RUE was found high in cv.GT-100 compared to cv.BDN-2. Functional relations were developed to estimate the near surface soil moisture content under developing conopics of pigeonpea using remotely sensed canopy and air temperatures, and the LAI. A linear relationship was observed between evapotranspiration and canopy-air temperature differential. The relation was found closely related, when the variations due to energy load was accounted. The populations of the eggs and larvae of the Helicoverpa were found to be highest in first date of sowing (D1) both at 50% flowering and 50% podding phases compared to D2 and D3. The cultivar GT-100 was found more succeptible to Helicoverpa due to the early flowering character than cv.BDN- 2. The larval population of Helicoverpa in pigeonpea was found significantly correlated with air temperature, vapour pressure and pan evaporation.ThesisItem Open Access CROP-PEST-WEATHER INTERACTION AND POPULATION DYNAMICS OF (Heliothis armigera (Hubner) IN TWO DIVERSE PIGEONPEA (Cajanus cajan (L.) Millsp.) GENOTYPES (BDN-2 and GT-100) AT ANAND(AAU, Anand, 1998) Chaudhari, G. B.; Shekh, A. M.The results obtained in this investigation revealed that the air temperature and photoperiod had profound influence on growth and development of the pigeonpea crop. The variation in air temperatures during different phenophases resulted in differential attainment of physiological maturity in both the genotypes. Whereas, the differential availability of bright hours of sunshine (BSS) during reproductive phase resulted in higher seed yield. Low vapour pressure (VP) and relative humidity (RH) during flower bud initiation to podding phase, were favourable for higher seed yield. The seed yield and other yield attributing characters of pigeonpea crop were significantly influenced by the different treatments. The seed yield of protected condition was observed 36% higher than that under unprotected condition. The short duration genotype, GT-100 was found significantly higher in seedyield than the long duration genotype BbN-2. The seed yield was found to decrease upto 35%, with delayed sowing till 40 days after the onset of monsoon. Significant differences in total biomass were noticed in treatments like irrigation, genotypes and dates of sowing The results from correlation study revealed that there was a positive significant association between seed yield and different weather parameters like, maximum and minimum temperatures, bright hours of sunshine and different thermal indices like, growing degree days, phototherraal units and Heliothermal units and accumulated PAR. It has been observed that there was a difference in growing degree days requirement for the two genotypes to attain different phenological phases. To attain physiological maturity the GDD requirement for BDN-2 was 3105°Cd and it was 2894°Cd for GT-100 genotypeThesisItem Open Access GROWTH, DEVELOPMENT AND YIELD ATTRIBUTES OF CHICKPEA (Cicer arietinum Linn.) IN RELATION TO WEATHER PARAMETERS(AAU, Anand, 1996) Rao, Gattineni Srinivasa; SAVANI, M. B.Chickpea or Bengal gram (Cicer arietinum Linn.) is one of the most important pulse crops in India. The crop is grown in the semi-arid tropical areas of India as a winter crop on stored soil moisture from the preceding rainy season. The crop is characterized as drought tolerant and the productivity is different in different environments. Many of the crop management practices developed have focused the water management aspects, neglecting the importance of energy interception and its efficiency. An experiment was conducted at Agronomy Farm of the B.A. College of Agriculture, Gujarat Agricultural University, Anand Campus, Anand during rabi season of 1994-95, on chickpea cv. ICCC-4 on the loamy sand soil with three dates of sowing and two pest control measures with Latin Square Design. The results obtained in this investigation revealed that the air temperature had profound influence on the growth and development of the chickpea crop. The differences in the total biomass per plant, number of pods per plant and seed yield per hectare among all the treatments were significant. The number of days taken for completion of the emergence phase was negatively and significantly correlated with mean values of pan evaporation and air temperature.. Significant positive correlations were observed for the minimum air temperature, morning and afternoon vapour pressures, and morning and afternoon relative humidities, with days taken for the completion of vegetative phase. The duration of pod setting phase was found to be significantly and positively correlated with sunshine duration (BSS), pan evaporation, wind speed but negatively correlated with both the morning and afternoon relative humidities. BSS had negative association with number of days taken for completion of the pod filling phase. During the maturing phase, most of the weather parameters were found to have significant association with the number of days taken for its completion.ThesisItem Open Access DYNAMIC MODELING OF DAILY WATER USE BY SUMMER PEARL MILLET ' (Pennisetum americanum L.)(AAU, Anand, 1995) Bodapati, Papuji Rao; Savani, M. B.Crop water use is a complex function of the climatic conditions, stage of the crop development and the soil water content. Models have been developed earlier using various approaches and levels of details to improve the prediction of evapotranspiration. Functional models with some empiricism can be used for routine applications than the mechanistic models. Transpiration from the pearl millet was found to be strongly influenced by leaf area than by stomatal conductance. Field experiments during the summer season of the years 1994 and 1995 were conducted with pearl millet cv. GHB-30. The experiments were laid out in split-plot design, with three dates of sowing as the main plot and four irrigation levels as the sub-plot treatments which were replicated four times. The results obtained in this investigation revealed that, air temperature had a profound influence on the growth and development of summer pearl millet. The optimum date of sowing was found to be February 15th , which would provide optimum environmental conditions for the growth and development of the crop. Different dates of sowing did not show any significant effect on the grain yield. Irrigating the crop at 25% depletion of available soil moisture gave the highest grain and biomass yields but its WUE was lower than that for the other irrigation levels. Pearl millet required about 310 GDD in summer season to build considerable GLAI and about 800 GDD to attain the maximum GLAI. A second-order polynomial was developed for estimating GLAI using the accumulated GDD. The FAO Kc, values had over-estimated ET rates and a second-order polynomial was developed to estimate daily Kc values from the accumulated GDD for non-stressed pearl millet. The rate of ET in pearl millet was found to decrease with an increase in soil moisture deficit and approached zero at a soil moisture depletion of 65% of the available soil moisture. PLANTGRO and MCD models when evaluated against the field data collected through this experiment, predicted ET reasonably better for nonstressed treatments than for stressed treatments. Of the two models, the MCD model predicted better for stressed condition than the PLANTGRO model. The functional relations for the PET estimation and root water uptake in the MCD model needed substantial modification. The separation of the PET in the PLANTGRO model did not suit the summer pearl millet. A one-day time step model BAJRAWAT had been developed in the 'C' language during the course of the present study, and was made User-friendly. Irrigation amount and the PET being its main driving forces, the partitioning of PET into soil evaporation and transpiration had been accomplished in BAJRAWAT by GLAI. The actual evaporation and transpiration depended on the availability of water in the surface soil and in the root zone and also on the depth of root penetration. The evaporation was assumed to take place from the surface soil only and the soil was further divided into four layers, from which water was assumed to have been removed by transpiration and drainage. Infiltration was assumed to have been taking place depending on the amount and the location of water already in the soil layers. The transpiration was computed as a function of GLAI and the available moisture in the root zone. The development of GLAI was considered to be controlled by thermal time and a moisture stress factor. The BAJRAWAT model when validated along with PLANTGRO and MCD models predicted ET better than the latter two models. The relative transpiration of summer pearl millet was found to be more closely associated with relative dry matter yield than with the relative grain yieldThesisItem Open Access STUDY ON PAR INTERCEPTION AND TESTING OF PLANTGRO MODEL FOR MUSTARD (BRASSICA JUNCEA L.) CROP(AAU, Anand, 1994) Patel, P. B.; Shekh, A. M.Mustard (Brassica juncea L.) is an important oil seed crop in India. Water is most often the limiting factor for mustard production and its optimum use is essential for higher yields. Evapotranspiration is an integral part of the overall water requirement' problem of any crop and its determination becomes both desirable and inevitable for better acquisition of the knowledge of water utilization by the crop. A field experiment with four depths of irrigation (T1-irrigation with 30 mm of water, Ig-irrigation with 45 mm of water, I o-irr igat ion with 60 mm of water and I4- irrigation with 75 mm of water) with four irrigations using sprinkler system each at a fixed interval was laid out in completely randomized block design during the rabi season of the year 1992-93. The results revealed that, the yield differences due to irrigation treatments were found to be non-significant. The data indicated that none of the irrigation treatments had any significant effect on the yield and yield attributing characters. The leaf area index (LAI) value was not sensitive to the different depths of moisture levels. Regression analysis between LAI and days after sowing (DAS) indicated that quadratic regression equation could fit well to predict LAI from DAS. Study on evapotranspiration indicated that total ovapotranspiration increased with increase in amount of water applied. Accumulated Stress Degree Days (SDD) values decreased with increase in amount of water applied. Correlation studies between dry matter production and intercepted photosynthetically active radiation (IPAR) indicated high positive correlations. Studies on intercepted photosynthetically active radiation (IPAR) indicated that IPAR use efficiencies ranged from 2.44 g MJ-1 in I2 treatment to 2.55 g MJ-1 in I1 treatment. The extinction co-efficient (K) calculated by using incident photosynthetically active radiation (PAR) and transmitted PAR showed a value of 0.87.ThesisItem Open Access CROP WEATHER RELATIONSHIPS IN SUMMER PEARL MILLET (Pennisetum americanum (L.) Leeke) AND TESTING OF CERES MILLET MODEL FOR THE MIDDLE GUJARAT AGROCLIMATIC ZONE(AAU, Anand, 1993) Maniyar, Vijayprakash Govindlalji; MEHTA, A. N.Pearl millet fPennisetum americanum (L.) Leeke) is one of the most important and widely cultivated cereal crop in the arid and semi-arid regions of the world. It is generally, grown as rainfed crop in rainy season in the scanty rainfall area and on poor soils. It is more resistant to drought than sorghum. It can sustain under higher temperature regimes. Under intensive cropping system, it has its own place and being cultivated during summer season, where irrigation facilities are available. Weather variables affect the crop growth differently in different phenophases during its growth cycle. Field experiments during summer season of 1991 and 1992 were conducted with Cv.GHB-30 and were laidout in split plot design, with three dates of sowing as main plot and four irrigation regimes as sub-plot, replicated thrice. The results obtained during the course of investigation revealed that, higher temperatures decreased the duration of the crop with the delay in sowing. Higher relative humidity during flowering stage gave higher grain yields. Higher grain yields were recorded from first date of sowing. However, reduction was lesser in second date of sowing. Late sown crop recorded lowest grain yields. Irrigation scheduled through IW/CPE = 1.0 proved best. However, irrigation scheduled by infrared thermometry could save about 30 to 35% of irrigation water with no much reduction in grain yields. Yield attribute such as earhead weight had positively contributed towards grain yield. Consumptive use of water increased with increase in the frequency of irrigation. However, water use efficiency was higher with lesser irrigation frequencies, indicating a drought resistance trait in summer pearl millet. Stress degree days had significant negative correlation with growth attributes. Decrease in leaf water potential during flowering stage had adversely affected the grain yields. Studies on Intercepted photosynthetic active radiation indicated higher IPAR use efficiencies in D2 treatment (15th Feb.sowing date) during both the years. The extinction coefficient (K) calculated showed a value of 0.89. Correlation studies between grain yield and weather parameters revealed that morning, afternoon and mean relative humidity upto flowering stage played a major role in deciding the final grain yield. During anthesis to dough stage both thermal interception rate (TIR) and intercepted photosynthetic active radiation (IPAR) showed significant positive correlation with grain yield indicating better source sink relationship. Stepwise regression analysis selected a model with mean relative humidity (during emergence to tillering stage) and hours of bright sunshine (during flag leaf to anthesis stage) as parameters for predicting grain yields, 20 to 25 days before maturity. Path analysis of grain yield and weather parameters observed in important phenophases indicated that higher relative humidity during flag leaf to dough stage and higher thermal interception rate (TIR) during anthesis to dough stage are found favourable for higher grain yields. Prediction model obtained for total biomass production selected only accumulated growing degree days (GDD) during emergence to tillering phase (P1). This model could predict the total biomass 50 to 60 days before maturity. CERES millet model corrected for genetic coefficients was found to be good for this region. CERES millet model could predict the anthesis date and maturity date with minimum error. However, grain yields and total biomass production predicted by CERES millet model showed larger percent error compared to that of grain yields and total biomass production predicted by regression models obtained in the study. Secondly, CERES millet model has the limitation of predicting the yield at the end of growing season. However, the prediction models obtained in the study could predict the grain yields and total biomass production well in advance.ThesisItem Open Access CROP WEATHER INTERACTION AND PLANT STAND ENVIRONMENT IN RELATION TO PRODUCTIVITY OF TWO DIVERSE PIGEONPEA (Cajanus cajan (L.) Millsp.) GENOTYPES(AAU, Anand, 1996) PATEL, N. R.; MEHTA, A. N.Pigeonpea (Cajanus caJan (L.) Mi lisp.) is a major pulse crop, usually grown under rainfed environment in the semiarid tropic (SAT) to supplement the protein-deficient human diets. Pigeonpea cultivation in rainfed condition can not be assured of success unless grown with climatological consideration of particular region. Although effect of weather on yields is complex, a possible understanding of crop weather interaction is an essential aid to crop management. Also, the optimization of structure of crop production environment in pigeonpea is an important way towards better utilization of natural resources. The experiments during kharif 1993 and 1994 were conducted comprising three sowing dates as main plot and combination of two genotypes and two row spacings as sub plot treatments in split plot design with four replications. The results obtained during the course of study indicated that weather played a significant role in deciding yield potentiality of GT-100 and BDN-2 genotypes. However, weather variables have affected the growth and yield different to both genotypes in different phenophases of growing period. Crop duration in GT-100 and BDN-2 was markedly increased due to extended vegetative phase in response to Tower air temperatures. Whereas, leaf area development and crop growth rate were enhanced by comparatively higher temperatures. Rainfall received during late reproductive period is also seemed to be a factor for increased crop duration, leaf area index and crop growth rate and consequently better partitioning into seeds. The results regarding the seed yield and total biomass revealed that early sowing date D1 (30th June) produced significanlty the highest seed yield as well as total biomass in pigeonpea. Further, any delay in sowing caused marked reduction in both seed yield and total biomass in pigeonpea. Higher yield in early sowing was due to accelerated vegetative and reproductive growth caused by uniform rainfall distribution and comparatively higher temperatures during reproductive period. The genotype GT-100 had registered more seed yield compared to genotypes BDN-2. Higher seed yield in GT-100 genotype under rainfed condition could be attributed to less terminal water deficit and efficient use of water towards reproductive strucutres due to early maturity and determinate growth habit of GT-100. Also, the pigeonpea seed yield and biomass were increased as the row spacing decreased from 90 to 60 cm. Because narrow row (60 cm) crop having greater plant stand had created an environment which led to better utilization of resources like photosynthetically active component of radiation and water during reproductive period for increase in yield of pigeonpea. The results regarding the canopy temperature based indices revealed that canopy air temperature differential and accumulated SDD exhibited significantly negative correlation in later reproductive phenophases in both GT-100 and BDN-2, indicating the need of protective irrigation either at flowering or podding to both genotypes in rainfed condition. The correlation of seed yield with weather parameters and agrometeorological indices indicated that the favourable effect of early sowing on seed yield in GT-100 and BDN-2 could be attributed to lower evaporation, maximum temperatures and vapour pressure deficit in the post vegetative phase and higher evaporation, maximum temperatures and vapour pressure deficit in the later reproductive phase alongwith low hours of bright sunshine and higher night temperatures throughout the growing season. Besides, extreme day or night temperatures had adverse influence on productivity of both genotypes throughout the growing season. Over and above, positive correlations of seed yield with CDD, Accu.HTU and Accu.PAR indicated that higher ODD after primary branch initiation and accu.HTU and accu. PAR in later reproductive phases (P4 or Ps) had favourably influenced the seed yield in GT-100 and BDN-2. However, indeterminate genotype BDN-2 responded well to accu.PAR and accu.HTU due to long duration and photo periodically sensitive genotype. The prediction model based on BSS and MaxT in the phenophase P2 , MinT in both P3 and Pe phenophases and TR in both Pa and PB phenophases was found suitable with good accuracy (R2 = 0.96) for predicting the seed yield of QT-100 at about 50-55 days prior to crop harvest. Likewise, model based on MaxT in phenophase P4 and MinT in phenophase Pe was found appropriate with R2 = 0.78 for predicting seed yield in BDN-2 at about 30-40 days before maturity. Thus, an agronomic strategy such as sowing of short duration genotype GT-100 by the end of June in 60 cm apart rows based on crop-weather relationship was found most appropriate for securing maximum seed yield of pigeonpea under rainfed condition in middle agroclimatic zone of Gujarat State.ThesisItem Open Access RESPONSE OF SUMMER MUNGBEAN TO WEATHER WITH VARYING IRRIGATION SCHEDULES AND TESTING OF BEANGRO MODEL FOR MIDDLE GUJARAT AGROCLIMATIC ZONE(AAU, Anand, 1999) Jadhav, Jayawant Dadaji; SAVANI, M. B.Mungbean {Vigna radiata (L.) Wilczek.) is one of the major grain pulse crop in tropical and sub-tropical regions of India. It being a photo and thermo-insensitive crop, is successfully raised in kharif as well as in summer seasons where the adequate irrigation facilities are available. Summer season provides an ideal condition for raising mungbean with quite handsome profits. Since, the effects of weather on yield are complex, it will need the deeper and clear understanding of the climatic factors affecting the growth and yield of mungbean. The field experiment during summer season of the years 1997 and 1998 was laid out in a split plot design with three replications. The three dates of sowing were assigned as a main plot treatment, three irrigation regimes and two varieties as sub-plot treatment. The results obtained during the course of study revealed that the weather had played a significant role in deciding the yield of mungbean. However, the weather variables had affected the crop growth and yield differently in different phenophases during its growing period. The results regarding the grain yield as well as total biomass of mungbean as influenced by the different dates of sowing showed that D2 sowing date noa produced significantly higher grain yield as well as total biomass. The similar trend was also found in yield attributing characters, such as number of branches per plant, pod length, seeds per pod and test weight. Irrigation scheduled through IW/CPE = 0.8 and variety K-851 proved best. The favourable effects of weather parameters for the growth and development of the crop was experienced by the D2 sown crop during the phenophases of flower bud initiation to 50 per cent podding in terms of the lower maximum temperature, higher vapour pressure and less hours of bright sunshine. Correlation coefficients between grain yield and weather parameters as well as agro-meteorological indices indicated that, the grain yield and morning time relative humidity was significantly negatively correlated in the phenophase Pi. There were significant positive correlations of grain yield with minimum temperature, afternoon vapour pressure and afternoon relative humidity in the phenophases P3 and P4 (50 per cent flowering to 50 per cent podding). The results also indicated that the lower temperatures at the time of flowering had delayed the flowering bud initiation and hence, the increased in the period of the phas ic development which had benifited in the crop production. The higher relative humidity prevailed during the flowering phase helped in proper seed setting by overcoming the pollen dessication and thereby, in good grain yield. The favourable impact of vapour pressure on grain yield ascribed the lower evaporative demand and thereby more vegetative growth and consequently more grain yield. The significant positive correlations exhibited by accumulated photosynthetically active radiation during the reproductive ontongeny resulted in more photosynthates available to the pods for their development. The positive correlations of accumulated thermal interception rate during P2 and P5 phases indicated that more available energy may help in allocation of synthesized assimilates towards the reproductive organs and thereby, producing more grain yield , Agro-meteorological indices like accumulated growing degree days and accumulated photothermal unit also exhibited significantly positive correlation with grain yield. Studies on intercepted photosynthetically active radiation indicated that the IPAR use efficiencies were observed more in D2 treatment (19th March sowing date) during both the years. The average value of the extinction coefficient (K) was obtained as 0.73.ThesisItem Open Access CROP WEATHER RELATIONSHIPS AND YIELD PREDICTION OF PIGEONPEA (Cajanus cajan (L.) MILLSP.) CV. GT-100 UNDER RAINFED CONDITION IN MIDDLE GUJARAT AGROCLIMATIC REGION(AAU, Anand, 1994) Khushu, M. K.; Mehta, A. N.Pigeonpea (Ca.ianus ca.ian (L.) Millsp.) is one of major grain legume crops in tropical and subtropical regions of India. It is generally grown as rainfed crop in scanty rainfall regions with minimum resources of water f0r irrigation. It is more drought resistant than any other field crop. It can sustain itself under higher temperature regimes. Since the effects of weather on yield are complex, need for a deeper and clear understanding of the climatic factors affecting the growth and yield of pigeonpea is necessary. The field experiments during Kharif seasons of 1992 and 1993 were conducted with Cv. GT-100 and laidout in randomised block design with four dates of sowing replicated five times. The results obtained during the course of study revealed that weather played a significant role in deciding the yield of pigeonpea. However, its variables affected the crop growth and yield differently in different phenophases during its growing period. The results regarding to the grain yield as well as total biomass of pigeonpea as influenced by dates of sowing showed that early sowing (D1) produced significantly higher grain yield as well total biomass, both of which decreased with delay in sowing. Similar trend was found in yield attributing characters, such as the number of pods per plant, seeds per pod and test weight as well as plant height. The favourable effects of early planting on crop growth and yield could be attributed to lower maximum temperatures in the phenophase from initiation of secondary branches %o flower bud initiation (P4) and higher night temperatures at pod setting phase (P6) in addition to higher vapoiir pressure, lower hours of bright sun shine throughout the growing season. The rainfall at flower bud initiation had also shown favourable effect in contributing to the higher yield of pigeonpea. Correlation of grain yield and total biomass with weather parameters and agrometeorological indices indicated that, besides the favourable effects of weather parameters discussed in the proceeding paragraph, the positive correlations of accumulated GDD and PTU in both vegetative period as well as flowering period in addition to accumulated PAR for entire period were found with grain yield and also with total biomass. The regression analysis between accumulated dry matter with accumulated PAR and accumulated GDD indicated that APAR use efficiency did not vary with the date of sowing while heat use efficiency did vary with the treatments. Path coefficient analysis revealed that rainfall in the phenophase P4, Min T and VP2 in the phenophase P6, Accu. GDD and Accu. PTU in the phenophase P8 and accumulated PAR in the phenophase P9 could be used efficiently in predicting grain yield of pigeonpea. Prediction models were developed by multiple regression technique for predicting grain yield. The model 4.6 based on RF in the phase P4, Min T and VP2 in the phenophase P6, accumulated GDD in the phenophase P8 and accumulated PAR "In the phenophase P9 with R2 = 0.95 was the best for predicting the grain yields at about 30 to 40 days before maturity. Standard partial regression coefficients provided relative importance of the parameters in predicting model and were in order VP2 (P6) Accu. GDD (P8). Min T (P6), RF (P4) and Accu. PAR (P9).