EFFECT OF SEED RATE AND PLANTING GEOMETRY ON WEED GROWTH AND YIELD OF LATE SOWN WHEAT (Triticum aestivum L.)
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Date
2004
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AAU, Anand
Abstract
A field experiment was conducted at college Agronomy Farm, B A College of Agriculture, Anand Agricultural University, Anand during Rabi season of 2002-2003 to study the effect of seed rate and planting geometry on weed growth and yield of late sown wheat (Triticum aestivum L.) under middle Gujarat condition. The soil of the experimental plot was loamy sand in texture, having sufficient drainage with pH 7.89. The soil status was medium in available nitrogen and phosphorus and high in available potash. Twelve treatment combination comprising two levels of seed rate (R1 -150 kg/ ha and R2 - 200 kg/ha), two planting geometries (S1 - row spacing at 22.5 cm and S2 - cross sowing at 22.5 cm) and three weed control-methods (W1 - weedy check, W2 - weed free and W3, pre- emergence application of pendimethalin 1.0 kg/ha). The experiment was laid out in factorial randomized block design with four replications. Results revealed that total weed count/ m2 and dry weight of weeds (g/m2) recorded lower under higher seed rate (R2 - 200 kg/ ha) whereas it was higher under lower seed rate (R1 -150 kg/ha) at 30, 45, 60 DAS and at harvest with weed control efficiency of 15.29 per cent. Total weed count/m2 and dry weight of weeds (g/m2) were significantly lower under criss cross sowing at 22.5 cm (S2) as compared to line sowing at 22.5 cm (S1) at all the growth stages. The weed control efficiency was recorded 19.89 per cent under R2 over R1 Weed control methods differed significantly in case of weed count/m2 as well as dry weight weeds (g/m2). Weed free (W2) recorded 100 per cent control of weeds at all the stages. However, weedy check showed the highest weed population and dry weight of weeds over rest of the treatments. Weed free (W2) recorded 100 per cent weed control efficiency followed by pre emergence application of pendimethalin 1.0 kg/ha (84.55 %). Crop sown with higher seed rate of 200 kg/ ha (R2) had significantly increased growth attributes viz., plant population/m2, plant height, crop dry biomass (g/plant), leaf area (cm2/plant) over lower seed rate of 150 kg/ha (R1) at all the growth stages. Plant height and crop dry biomass were significantly greater at all the growth stages except at 60 and 75 DAS in respect to plant height and only at 45 DAS incase of crop dry biomass. However, leaf area (cm2/plant) was markedly increased under lower seed rate (150 kg/ha) at all the stages. Similarly, yield attributing characters like length of spike, number of spikelets/spike, number of grains/spike and test weight (g/1000 grains) were maximum under lower seed rate (150 kg/ha) than these recorded under higher seed rate (200 kg/ha). While a number of productive tillers/m2 and total tillers/m2 recorded maximum under higher seed rate (200 kg/ha) than these of lower seed rate (150 kg/ha) resultantly produced more grain, straw and biological yields. The reverse was true for non-productive tillers/m2. Harvest index (%) did not significantly under both rate of seed. In case of planting geometry, the periodical plant height measured at various growth stages and plant population/m2 (15 DAS) did not differ significantly. Whereas, leaf area (cm2/plant) at 45 and 75 DAS as well as crop dry biomass (g/plant) at 75 DAS showed significant increase under criss cross sowing at 22.5 cm (S2). over line sowing at 22.5 cm (S1). Further, yield attributes like productive tillers/m2, total tillers/m2, length of spikes, number of spikelets/spike, number of grains/spike, grain yield, straw yield, biological yield were increased significantly under criss cross sowing (S2) over line sowing at 22.5 cm (S1). While non-productive tillers/m2 and harvest index (%) were found to be non-significant. Among the weed control-methods, there was no significant difference found in plant population/m2 (15 DAS) as well as plant height at various growth stages except at 45 DAS. Significantly the greater leaf area (cm2/plant), length of spike, number of spikelets/spike, number of grains/spike, test weight (g) and in turn more grain yield, straw yield and biological yield were recorded under weed free treatment compared to weedy check but it was closely followed by pre emergence application of pendimethalin 1.0 kg/ha. Grain yield established positive and significant correlation (r) with most of the growth and yield attributes. While negative and significant correlation was obtained with total weed population/ m2 as well as dry weight of weeds (g/m2). Thus, the present study indicated that potential production and profit, from wheat variety GW-173V. under late sown condition, can be secured by cross sowing at 22.5 cm along with 200 kg/ha of seed rate in all three conditions i.e no weed control, weed free condition and chemical weed control (pre-emergence application of pendimethalin 1.0 kg /ha ). However, inorder to derive maximum yield and monetary return, crop field should be kept weed free either manual weeding or pre-emergence application of pendimethalin @ 1.0 kg/ha.
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AGRONOMY, AGRICULTURE, A STUDY