Abstract
An investigation on “Weed Management and Crop Growth Modeling in Soybean” was carry out on red sandy loam soil at UAS, Main Research Station, Hebbal, Bangalore during Rabi 2010 (September to December). The weed control practices included in the study were i) Pendimethalin 30 EC 1.0 kg a.i./ha – 3 days after sowing, ii) Imazethapyr 10 SL 100 g a.i./ha – 20 days after sowing, iii) Quizalofop-p-ethyl 5 EC 50 g a.i./ha – 20 days after sowing, iv) Chlorimuron ethyl 25 WP 6 g a.i./ha – 20 days after sowing, v) Hand weeding (20 & 40 DAS) and vi) un-weeded control. The experiment was designed as RCBD with four replications. Growth models – Richards, Logistic, Cubic polynomial and Quadratic polynomial simulated the course of dry matter production/plant by >97per cent under all weed management practices, indicating that weed competition did not alter the pattern of crop growth, but affected the total production substantially.
Highlights
Shift in weed flora is resulted from selection pressures imposed by modifications in the agricultural practices which alter their habitat directly or indirectly
The traditional methods of weed control by hand weeding or mechanical means are becoming costly, tedious, labour intensive and time consuming, and at times not able to be adopted in view of non-availability of laborers.With the availability of computers for analysis, mathematical models are being developed to quantify yield losses due to weed competition and to study the differential responses of weeds to herbicides [1]
Total dry matter production was regressed for various stages in days by using linear, quadratic, cubic, Logistic and Richards function under various weed management practices and provided in Table 1 Under all weed management practices, growth models namely Logistic, Richards and cubic polynomial models simulated total dry matter production per plant at various growth stages by more than 98 to 99 %, indicating similarity in crop growth
Summary
Shift in weed flora is resulted from selection pressures imposed by modifications in the agricultural practices which alter their habitat directly or indirectly. This selection pressure has brought in many new problems like susceptible weeds becoming resistant owing to continuous use of herbicides having similar mode of action, recent trends of using very low doses of highly potent herbicides, reduced tillage and less turnaround time under highly intensive farming system. Suitable choice of weed management practice is needed for crops, to sustain high productivity at a reasonable cost. Revised Manuscript received on August 13, 2021.
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