UPADHYAY, P. N.VADODARIA, R. P.2018-05-142018-05-142000http://krishikosh.egranth.ac.in/handle/1/5810045462A field experiment was conducted on loamy sand soil of College Agronomy Farm, Gujarat Agricultural University, Anand Campus, Anand, to study the response of wheat (Triticum aestivum (L.)) to water and weed management and residual effects of herbicides on succeeding sunmier bajra and green gram during the years 1997-98 and 1998-99. The treatments comprised of three levels of irrigation (irrigation at critical growth stages, IW/CPE ratios 0.7 and 0.9), relegated to main plots and eight weed management practices viz., pendimethalin @ 1.0 kg ha-1 pre-emergence, 2,4-D (Ethyl ester) @ 0.75 kg ha-1 post-emergence, isoproturon @ 1.0 kg ha-1 pre-emergence, isoproturon @ 1.0 kg ha-1 post-emergence, oxyfluorfen @ 0.250 kg ha-1 pre-emergence, sulfosulfuron @ 0.025 kg ha-1, weed free (two hand weedings at 20 and 40 DAS) and unweeded control (weedy check) as sub-plot treatments. Thus, twenty four treatment combinations were tested in split plot design with four replications. The recommended dose of 120-60-40 kg ha-1 of N-P2O5-K2O were applied common to all the experimental plots. After harvest of wheat crop, the bajra and green gram crops were superimposed in summer with recommended package of practices in split plot design. The soil of the experimental fields was loamy sand in texture (locally known as Goradu soil), having good drainage and fairly moisture retention capacity with pH ranging from 7.7 to 8.2. The soil was placed in fertility scale of low in total nitrogen, medium in available phosphorus and fairly rich in available potash with alkaline reaction. The results revealed that the growth characters like periodical plant height and leaf area plant-1 appreciably improved when irrigation was applied either at critical growth stages (I1) or at 0.9 IW/CPE ratio (I3) over 0.7 IW/CPE ratio (I2) during second year only. The yield attributes viz., effective tillers plant and ear length significantly increased under higher frequency of irrigation (I1 and I3) when compared with lower frequency 0.7 IW/CPE ratio (I2) during both the years and in pooled analysis. Similar trend was observed for ear as well as test weight under the same water management treatments in one out of two years and in pooled analysis. Likewise, grain weight ear-1 was also significantly increased with same irrigation levels during second year only, whereas, spikelets ear-1 and number of grains ear-1 remained unaffected. Water management treatments IW/CPE ratio 0.9 and irrigation at critical growth stages also yielded significantly the highest crop biomass (11420, 11502 and 11384 and 11536), straw (6288, 6326 and 6293, 6385 kg ha-1) and grain yield (5132, 5176 and 5091 and 5150 kg ha-1) over irrigation at 0.7 IW/CPE ratio (10540 and 10766 kg ha-1), (5726 and 5824 kg ha-1) and (4814 and 4942 kg ha-1) during second year and in pooled analysis, respectively, whereas harvest index remained unaffected due to water management treatments. Protein content in wheat grain significantly increased at 0.7 IW/CPE ratio over rest of the water management treatments during second year. Irrigation at 0.7 IW/CPE ratio significantly increased N and K content in grain and straw of wheat over 0.9 IW/CPE ratio and irrigation at critical growth stages during second year and in pooled analysis. Contrary to N and K content, their uptake by wheat crop remained unaffected due to water management treatments throughout the investigation period. On the other hand, phosphorus content in grain and straw of wheat and its uptake by wheat crop were significantly higher at 0.9 IW/CPE ratio and at critical growth stages over 0.7 IW/CPE ratio during both the years as well as in pooled analysis. Nutrients (NPK) content and their uptake by weeds remained unaffected due to water management treatments during entire period of experimentation. However, P2O5 content in weeds significantly increased at 0.7 IW/CPE ratio over rest of the treatments during second year. Population of monocot, dicot, sedge and total weeds and their dry weight m-1 at 25 days after sowing remained unaffected by water management treatments. However, population of dicot weeds m-1 at 25 DAS significantly increased at 0.7 IW/CPE ratio over 0.9 IW/CPE ratio and irrigation at critical crop growth stages during second year. However, the dry matter accumulation of weeds at harvest and weed control efficiency remained unaffected by water management treatments. Irrigation at 0.7 IW/CPE ratio significantly increased water-use efficiency over rest of the irrigation treatments during both the years of investigation. Irrigation at 0.9 IW/CPE ratio obtained the highest net returns of Rs. 19519 ha-1 and CBR of 1:2.56, followed by irrigation at critical growth stages with net returns of Rs. 19244 ha-1 and CBR of 1:2.52. Growth characters like plant height at harvest and leaf area plant remained unaffected by weed management treatments during both the years and in pooled analysis. However, the plant height recorded at 30, 60 and 90 DAS significantly affected due to weed management treatments. The lowest plant height was recorded at 30 and 60 DAS with pre-emergence application of isoproturon @ 1.0 kg ha and oxyfluorfen @ 0.25 kg ha-1 due to their phytotoxic effect on wheat crop when compared with other treatments during both the years as well as in pooled analysis. Post-emergence application of isoproturon @ I.O kg ha-1 (W4), weed free two hand weedings at 20 and. 40 DAS (W7) and pre-emergence application of pendimethalin @ 1.0 kg ha-1 (Wi) being at par but they recorded significantly the highest yield attributes viz., effective tillers plant-1, ear length, grain weight ear-1 and test-weight when compared with rest of the weed management treatments during entire period of experimentation. However, ear weight, spikelets ear-1 (except second year) and number of grains ear-1 remained unaffected by weed management Significantly higher values of crop biomass was obtained with post-emergence application of sulfosulfliron @ 0.025 kg ha-1 (11235 kg ha-1) but was at par with W3, W4, W5 and W7 during second year. However, it was lowest under unweeded control over rest of the treatments during second year, whereas, straw yield obtained highest with post-emergence application of sulfosulfuron @ 0.025 kg ha-1 followed by pre-emergence application of isoproturon @ 1.0 kg ha-1 and it was significantly superior over rest of the treatments during second year only. Significantly higher grain yield of wheat was recorded under post-emergence application of isoproturon @ 1.0 kg ha-1 (5430, 5224 and 5327 kg ha-1), followed by two hand weedings at 20 and 40 DAS (5429, 5075 and 5252 kg ha-1) and pre-emergence application of pendimethalin @ 1.0 kg ha-1 (5364, 5091 and 5227 kg ha-1) when compared with rest of the treatments during both the years and in pooled analysis, respectively. Harvest index recorded significantly higher with post-emergence application of isoproturon @ 1.0 kg ha-1 (W4), though remained at par with W], W7 and W2 during first year as well as in pooled analysis. Significantly the highest protein content in wheat grain was obtained under post-emergence application of isoproturon @ 1.0 kg ha-1 over rest of the treatments during second year and lowest under unweeded control. However, in pooled results, it was at par with W2, W3 and W7. Comparatively higher values of N, P and K content in wheat grain were recorded under effective weed management treatments viz., W4, W7 and Wi compared to other treatments, however, erratic trend was observed during individual years. Uptake of N and P by wheat at harvest was significantly higher under W4, W7 and W1 during both the years as well as in pooled results. The same treatments recorded significantly the highest uptake of K by wheat during second year only. The chemical analysis of weeds showed that the concentration of nutrients (NPK) in weeds at harvest remained unaffected by weed management treatments during second year and in pooled analysis. However, the concentration of N and P2O5 in weeds was higher with W4 (post-emergence application of isoproturon @ 1.0 kg ha-1), followed by W2, W3 and Wi during first year. Depletion of nutrients (N, P2O5 and K2O) by weeds at harvest was highest under unweeded control (Wg) throughout the investigation period and the lowest under W7, W4, W1 and W3. The degree of content and uptake of nutrients depend on the effectiveness of different weed management treatments. Population of monocot, dicot and total weeds m-1 at 25 DAS recorded highest with W2, W4, We and Wg and the lowest under rest of the treatments in which herbicides were applied as pre-emergence for controlling weeds. Population of sedge remained inconsistent throughout the investigation as it was not killed by any of the herbicides used in the present study. Significantly the highest dry matter accumulation of weeds at harvest was under unweeded control and the lowest with W4, W7, Wi, W3 and W2 and were at par among themselves in pooled analysis. Water-use as well as weed control efficiency were significantly higher under post-emergence application of isoproturon @ 1.0 kg ha-1 but was at par with weed free-two hand weedings at 20 and 40 DAS and pre-emergence application of pendimethalin @ 1.0 kg ha-1 during both the years and on pooled data basis. Post-emergence application of isoproturon @ 1.0 kg ha-1 recorded the highest net returns of Rs. 20847 ha-1 and CBR of 1:2.75, followed by weed free with net returns of Rs. 20128 ha-1 and CBR of 1:2.64. Almost all the growth and yield attributes remained unaffected due to interaction effect of water and weed management treatments (IxW) except grain weight ear-1 it was recorded highest with treatment combination I3W4 , followed by Ii W4 and the lowest under unweeded control at all the irrigation levels. Crop biomass and straw yields were recorded higher when crop was irrigated with high frequency of irrigation (I1 and I3) with almost all the weed management treatments when compared with lower frequency of irrigation (I2). By and large, higher values of grain yield and uptake of N and P by wheat as well as weed control efficiency were recorded when crop was irrigated with higher rates of irrigation (I1 and I3) clubbed with an effective weed management treatments like W4, W7 and Wi in most of the cases. Protein content was highest under low frequency of irrigation combined with W4, W1 and W7. Removal of nutrients (NPK) by weeds and dry weight of weeds at harvest were higher vinder unweeded control with all the water management treatments. The highest net returns of Rs. 21299 ha-1 and CBR of 1:2.74 were realized when crop was irrigated at critical crop growth stages with post-emergence application of isoproturon @ 1.0 kg ha-1, followed by net returns of Rs. 21118 ha-1 and CBR of 1:2.75 were obtained when crop was irrigated at 0.9 IW/CPE ratio alongwith the post-emergence application of isoproturon @ 1.0 kg ha-1. The weed management treatments (herbicides) applied to preceding wheat crop did not leave any residue in the soil to affect the germination, growth and yield parameters of the succeeding summer bajra and green gram crops adversely or favourably. Based on the results of two years field experiment, it can be concluded that for potential production and higher net returns from wheat cv. GW-496 in loamy sand soil of Middle Gujarat, the crop should be irrigated either at critical crop growth stages viz., crown root initiation, tillering, late jonting, boot, flowering, milking and dough stages IV or scheduling irrigation at 0.9 IW/CPE ratio and maintaining weed free condition either by the application of isoproturon @ 1.0 kg ha-1 as post-emergence (30 DAS) or with two hand weedings at 20 and 40 days after sowing.enAGRONOMY, AGRICULTUREA STUDYThesis