Impact of sowing methods and weed control practices on yield and economics of wet direct seeded rice

Wet direct seeding is proved as a viable alternate to conventional transplanting method of rice. Maintenance of optimum population by adopting an appropriate sowing method followed by judicious weed control practices ensures profitability of wet direct seeded rice (W-DSR). A field experiment was carried out to find out a suitable sowing technique and weed control options for enhancing productivity and economics of W-DSR. The W-DSR was infested with twelve numbers of weed species comprising of eight families under different sowing methods. The composition of sedges, broadleaved (BLW) and grassy weeds was 83.07, 11.0 and 5.93%, respectively. Irrespective of sowing methods, weeds such as, Echinochloa glabrescens and Leptochloa chinensis among grasses, Cyperus difformis and Scirpus juncoides among sedges and Lindernia anagallis among BLW were dominant. Drum seeding recorded 6.9 and 12.7% higher gross and net return, respectively than broadcasting, but it was at par with spot seeding. Highest B: C ratio of 2.07 was recorded with drum seeding, whereas spot seeding recorded lowest B: C ratio (1.99). Crop-weed competition caused 31.7% reduction in grain yield with W-DSR. Application of early post-emergent herbicide bensulfuron-methyl + pretilachlor @ 60+600 g/ha at 10 DAS, azimsulfuron @ 35 g/ha at 20 DAS, and bispyribac sodium @ 30 g/ha at 20 DAS recorded increase in grain yield 40.3, 40.1 and 39.8%, respectively over the weedy check. Ready mix bensulfuron-methyl + pretilachlor @ 60+600 g/ha at 10 DAS registered highest B: C ratio (2.16) but it did not vary significantly with bispyribac sodium @ 30 g/ha and azimsulfuron @ 35 g/ha.

Weed Management under Phosphorus Enrichment in Groundnut (Arachis hypogaea L.)

Background: Weeds infestation is one of the major threats to crop production and leads to severe crop-weed competition which finally reduce the crop productivity in term of quality and quantity. To enhance crop productivity therefore efficacy of various pre and post-emergence herbicides were evaluated on the basis of Amaranthus viridis, Commelina benghalensis and Cynodon dactylon population reduction, nutrient concentration and their uptake by groundnut. Methods: The present investigation was conducted consecutively for two kharif seasons of 2016 and 2017, at Instructional Farm, CTAE, MPUAT, Udaipur with six weed management practices and four phosphorus levels thus, 30 treatment combinations; all were evaluated in split-plot design with three replications. Result: The experimental results revealed that all herbicidal treatments as well as weed free recorded significantly lowest weed density as well as highest weed control efficiency, nitrogen, phosphorus and potassium concentration and also their uptake by groundnut as compared to weedy check except quizalofop-ethyl at 30 DAS in respect to control Cynodon dactylon. Further, pod yield response to phosphorus was found quadratic. The results also showed that phosphorus exhibit significantly increase nutrients concentration and their uptake by groundnut over control during the experimentation.

Efficacy of integrated weed management practices on yield and yield contributing parameters of black gram (Phaseolus mungo)

A field investigation was carried out during Kharif season in 2010 at Agronomy Department Farm,Dr.Panjabrao Deshmukh Krishi Vidyapeeth, Akola, to evaluate the effect of four herbicides (imazethapyr, pendimethalin,fenoxyprop-p-ethyl and quizal ofop -p-ethyl ) applied at different rates with different time of application (pre-emergence,post emergence and combination of both) and cultural practices onyield and yield contributing parameters of black gram (Phaseolus mungo). Data revealed that different chemicals and cultural weed control practices were exhibited their superiority over weedy check and reduced the crop weed competition by controlling the annual and broad leaved weeds. Among all the weed control treatments, pre-emergence application of pendimethalin @ 1.5 kg/ha showed higher grain weight plant-1 (4.87), number of pods plant (16.27),number of seeds per pod (7.00) and yield per ha (10.05).

A REVIEW ON NON-CHEMICAL WEED MANAGEMENT IN MAIZE (ZEA MAYS L.)

Weed is omnipresent species that compete with major crops for light, nutrients, space, and water for their growth and development and ultimately deteriorate the ideal environment for crops growth. In the present context, herbicide application is the easiest and seemingly economical approach for weed control in south-Asian countries. In contrary, the side effects of herbicide on health and environment impose to adopt for the non-chemical method of weed management. This paper reviewed the menace of herbicide, crop weed association, the critical period of crop-weed competition, and different methods of organic weed control implemented especially for maize. The main objective of this review is to maneuver a weed control strategy for maize other than the chemical application. The findings of different research suggested that a critical period of crop-weed competition in maize lies between 2 to 8 weeks after crop sowing. Many mechanical methods for weed control in maize proved efficient but seemed labour intensive and biological methods provided maximum security against specific weed species. The cultural method in combination with other methods effectively reduced the weed population in the maize field. It was found that, if various components of non-chemical weed management are implemented systematically, we can control the weed population with higher economic return and achieve the goal of organic food production with sustainable solutions. Weed control in the organic system focuses on management techniques designed to prevent weed emergence, give a competitive advantage to the main crop, and act for sustainable solutions. The non-chemical integrated weed management system is recommended to reduce the use of herbicide and for sustainable production. A review of non-chemical weed management in maize could be helpful for researchers to provide useful, sustainable, and environmentally friendly solutions to farmers to solve the problem of weed infestation in the maize crop along with substantial yield improvement.

Use of multispectral images to evaluate the efficacy of pre-emergent herbicides in peas under greenhouse conditions

In Colombia, peas are the second most important legume after the bean, and weeds are the main biotic factor that limits production, causing losses of up to 100%. Manual control can represent up to 40% of the labor force. The critical period in the crop-weed competition is the first third of the crop cycle; therefore, pre-emergent herbicide applications are a cost-effective way to control weeds. Common variables for assessing weed-control efficacy include, weed density (individuals/area), which is precise but time consuming, and weed coverage (%), which is faster but very subjective. Therefore, pre-emergence herbicides and a weed-control evaluation method that standardizes, facilitates, and provides greater precision are needed for peas cultivation and experimentation. Five pre-emergent herbicides (linuron, S-metolachlor, metribuzine, oxifluorfen and pendimetalin) were evaluated at two doses in a greenhouse pea crop. Also, two methods (quantification process of multispectral images and conventional human visual) for assessing weed coverage and control efficacy were compared. The best herbicide treatment for the dry grain yield was metribuzine (2.36 t ha-1). Furthermore, the effectiveness of the weed control was 88% at 36 days after sowing, which is optimal. Finally, there was agreement between the weed assessment methods (human vs. machine). The intraclass correlation coefficient was over 0.95, which validates the use of machine quantification for weed coverage.

Effect of Weed Management Practices on Weed Dynamics, Nutrient Depletion, Productivity and Profitability of Summer Mungbean (Vigna radiata) under Zero Tillage Condition

Background: Weeds are prime factor that adversely effects on growth, quality and yield of mungbean during summer and rainy season. Being a short duration crop, it faces heavy weed competition right from the early growth stages to harvesting. The critical period of crop weed competition in mungbean was initial 25-30 days, yield may be reduce up to 50-90% if weeds not manage at this stage. Hence, there is a need to find out the successful weed management strategies to realize higher growth and yield. The progressive transformation of agriculture concerning intensive use of herbicides is gaining status in recent years due to easy, lower cost, timeliness and successful controlling weeds. Therefore, keeping above information in view, the present study was undertaken to assess the effect of different weed management practices in summer mungbean under zero tillage condition to find out the better weed management, higher productivity and profitability.Methods: In this field-laboratory investigation during summer season, 2019, different herbicides were applied to manage weeds in mungbean. Eight treatments were applied based on various application windows. In the field and laboratory, the collected samples were determined for crop weed competition, yield attributes, yields and net returns. Result: The results revealed that weed free treatment was recorded lowest weed population at 30 DAS and harvest (1.8 and 2.9), weed dry weight (1.1 and 1.9g) and highest weed control efficiency (96.3 and 94.9%) followed by Pendimethalin (PE) fb one HW and Shaked (Propaquizafop + Imezathyper) application. The similar results also observed in nutrients removed by weeds. Among yield attributes, weed free treatment recorded the longest pod length, no. of pods/plant, no. of seeds/pod and test weight (7.9, 21.0, 9.7 and 43.0g, respectively) which was at par with Pendimethalin (PE) fb one HW and Shaked (Propaquizafop + Imezathyper) application. The magnitude of seed yield was increased under weed free (10.1 q/ha) and Shaked (Propaquizafop + Imezathyper) (9.5 q/ha) treatments by 127.9 and 113.8%, respectively over weedy check. Application of Shaked (Propaquizafop + Imezathyper) recorded highest net returns (Rs 55,079/ha) and B: C (2.8) over rest of the treatments. It can concluded that application of Shaked (Propaquizafop + Imezathyper) @ 2 L/ha at 20 DAS recommended for better weed control, higher yield and net returns of summer mungbean under zero tillage condition.

Hyperspectral Reflectance and Indices for Characterizing the Dynamics of Crop–Weed Competition for Water

Understanding the spectral characteristics of crops in response to stress caused by weeds is a basic step in improving the precision of agricultural technologies that manage weeds in the field. This research focused on the competition between corn (Zea mays) and redroot pigweed (Amaranthus retroflexus), a common weed that strongly reduces corn yield. The aim of this research was to characterize the physiological changes that occur in corn during early growth because of crop–weed competition and to examine the ability to detect the effect of competition through hyperspectral measurements. A greenhouse experiment was conducted, and corn plants were examined during early growth, with and without weed competition. Hyperspectral measurements were combined with physiological measurements to examine the reflectance and photosynthetic activity of corn. Changes were expected to appear mainly in the short-wave infrared region (SWIR) due to competition for water. Relative water content (RWC), chlorophyll content, photosynthetic rate, and stomatal conductance were reduced in the presence of weeds, and intercellular CO2 levels increased. Deeper SWIR light absorption occurred in the weed treatment as expected, accompanied by spectral changes in the visible (VIS) and near infrared (NIR) ranges. The results highlight the potential of using spectral measurements as an indicator of competition for water.

Managing the orchard environment.

This chapter focuses on the importance of managing the orchard environment for a sustainable sweet cherry production, i.e. fertilizer application, irrigation and crop-weed competition, among others. The influence of some climate-related environmental factors on sweet cherry production are also discussed.

Critical period of weeds interference in pineapple (Ananas comosus [L.] Merr.) crops

Description of the subject. In crop-weed competition, some periods are critical because they may interfere with the crop production capacity. Therefore, knowing these periods is crucial when deciding on the best time for control and preparation of the Integrated Management Program. Objectives. To determine the Period Prior to Interference, Total Period for Interference Prevention, and the Critical Interference Period in pineapple cultivation. Method. The experimental design consisted of randomized blocks in 2 x 15 factorial arrangement, four replications, and two management systems: weeds control and crop-weeds coexistence; 15 increasing periods of 30 days each after planting: 0, 30, 60, 90, 120, 150, 180, 210, 240, 270, 300, 330, 360, 390, 420. In the control treatments, since planting, manual weeding (with hoe) and mechanical weeding (with brush cutter) were done during increasing periods of time, and in the coexistence treatments, the weeds lived together with pineapple plants and, at the end of each period, weeds control was made with mechanical and chemical weeding. Results. The best yields were achieved in the periods of less coexistence with weeds. The critical periods for interference prevention with 5 and 10% of yield losses were 259 and 204 days, respectively. Conclusions. The critical period for interference prevention lasted 14-259 days after planting of the pineapple offsets.