Selectivity ofHerbicides Applied Isolated and inCombinations in Grain Sorghum

Background: Chickpea (Cicer arietinum L.) is the most important pulse crop widely cultivated for its nutritional and economic value. However, weed infestation poses a significant challenge to chickpea production, leading to reduced growth and productivity. Effective weed management strategies are therefore essential to mitigate the losses due to weeds and improve crop productivity. Selective herbicides with low or no phytotoxicity to the crop offer a promising solution for controlling weeds in order to boost up crop productivity. Currently available post emergence herbicides such as imazethapyr, can cause phytotoxic effects on chickpea. Therefore, it is essential to identify new post-emergence herbicides that can effectively control weeds without harming plant health. This study investigates the impact of topramezone, a selective post-emergence herbicide, on weeds as well as growth and productivity of chickpea. Methods: A field experiment was conducted at Agricultural Farm of Palli Siksha Bhavana, Visva-Bharati, Sriniketan during rabi season of 2021-22 and 2022-23. The experiment was laid out in randomized block design with nine treatments and three replications. The treatments were - T1 - topramezone 15 g ha-1 as POE, T2 - topramezone 17.5 g ha-1 as POE, T3 - topramezone 20 g ha-1 as POE, T4 - topramezone 22.5 g ha-1 as POE, T5 - topramezone 25 g ha-1 as POE, T6 - imazethapyr 60 g ha-1 as POE, T7 - pendimethalin 750 g ha-1 as PE, T8 - weed free and T9 - unweeded control. The study assessed the density and dry weight of weeds, weed control efficiency, growth and yield parameters as well as yield of chickpea under various application doses of topramezone in comparison with imazethapyr and pendimethalin. Result: Among all the herbicides, post-emergence application of topramezone 25 g ha-1 at 25 days after sowing resulted the lowest density and dry weight of weeds, the highest growth (plant height, LAI) and yield parameters (number of pods plant-1, number of seeds pod-1), seed yield and harvest index. Therefore, post-emergence application of topramezone 25 g ha-1 at 25 days after sowing proved to be an effective herbicide for weed control in chickpea in the lateritic belt of West Bengal.

Weeds pose a significant challenge in maize fields in the Dang district, leading to a substantial 52% reduction in yield. Hence, this study was conducted in Satbariya village of Dang, Nepal, in 2023 to evaluate the impact of various weed management practices on weed dynamics, growth, and yield of spring maize. The experiment included seven treatments: a weedy check, weed-free plot, pre-emergence application of atrazine at 1.25 a.i. kg/ha (AtPrE), post-emergence application of atrazine at 1.25 a.i. kg/ha (AtPoE), manual weeding at 30 DAS, mini-tiller at 30 DAS, and LaPoE (tembotrione 42% SC + atrazine 50% WP) applied as post-emergence. The Subarna variety of maize was chosen for the study. Fifteen weed species from seven different families were identified in the experimental area. Specific morphological and phenological parameters, such as plant height and days to tasseling and silking, were not significantly influenced by the weed control methods. However, significantly lower weed density and biomass were observed in the weed-free plot and LaPoE. Similarly, weed-free plots and LaPoE exhibited significantly higher weed control efficiency (WCE) and weed control index at both 45 and 60 DAS, leading to a lower weed index (0.00–16.71%) and more effective weed control. Concerning the yield parameters, cob length, number of kernels per row, and 1000-grain weight were significantly higher in weed-free plots, followed by LaPOE, and the highest grain and biological yield were observed in weed-free plot (6.14–15.18 tons/ha) and LaPoE (5.12–13.32 tons/ha). Moreover, the benefit-cost ratio and net return were observed to be highest with LaPoE. This study suggests that LaPoE can be an effective and economical weed management strategy for increasing maize yield and profitability. Further research could explore the long-term effects of using LaPoE on weed control and crop productivity.

Pearl Millet Tolerance to Selected Herbicides

A field experiment was conducted at Instructional Farm, Navsari Agricultural University, Navsari during 2013–14 and 2014–15 with a view to study the crop-weed competition as influenced by different weed management practices in Rabi (winter season) sorghum (Sorghum bicolor L.). Twelve weed management treatments were evaluated in a randomized block design with four replications. Preemergence (PE) application of atrazine 0.5 kg/ha + pendimethalin 0.25 kg/ha as tank mixture significantly reduced weed population and weed biomass, increased the weed control efficiency at early stage, next to weed free treatment. However, at the rest of the growth stages, two HW and inter culturing (IC) at 20 and 40 DAS, atrazine 0.5 kg/ha PE + HW and IC at 20 DAS, pendimethalin 0.5 kg/ha PE + HW and IC at 20 DAS effectively controlled the weeds, reduced the weed biomass and increased the weed control efficiency. Nutrient losses by weeds were highest under unweeded control and lowest with weed free condition followed by application of atrazine 0.5 kg/ha PE + HW and IC at 20 DAS.

Sorghum is a potential crop as feed forage. The objective of the research was to obtain optimum dose of liming to improve the growth and productivity of sorghum (Sorghum bicolor (L.) Moench) biomass as feed forage. A completely randomized design with 4 treatments and 4 replications were applied for the research. The treatments were doses of dolomite lime addition i.e., 1) SD0 (dolomite lime addition at a dose of 0 ton/ha) as a control, 2) SD1 (dolomite lime addition at a dose of 1 ton/ha), 3) SD2 (dolomite lime addition at a dose of 2 ton/ha), and 4) SD3 (dolomite lime addition at a dose of 3 ton/ha). The result shows that supplementation of dolomite lime at doses of 2‒3 tons ha-1 can increase soil pH after a week of incubation. The dolomite lime addition at a dose of 3 tons ha-1 significantly increases (P<0.05) the plant height (2 weeks after planting) and the number of leaves from a week after planting until the end of the research (10 weeks after planting). In addition, this dose of dolomite addition (3 tons/ha) can increase fresh biomass productivity as well as dry biomass compared to control (SD0). In conclusion, supplementation of dolomite lime at a dose of 3 tons ha-1 was effective to increase the pH value of soil, plant height, leaves number, as well as fresh and dry biomass of sorghum plant. In addition, this dose of dolomite lime produces better green color of sorghum plant leaf compared to without liming. Keywords: biomass production, dolomite lime, feed forage, Sorghum bicolor (L.) Moench

The pre-emergent herbicide indaziflam is efficient in the management of weeds in eucalyptus crops, but this plant may develop less in soil contaminated with it. The objective was to evaluate the levels of chlorophylls a and b, the apparent electron transport rate (ETR), growth and dry mass of leaves, stems and roots of Clone I144, in clayey soil, contaminated with the herbicide indaziflam and the leaching potential of this herbicide. The design was completely randomized in a 3 × 5 factorial scheme, with four replications. The leaching of indaziflam in the clayey soil profile (69% clay) was evaluated in a bioassay with Sorghum bicolor, a plant with high sensitivity to this herbicide. The injury and height of this plant were evaluated at 28 days after sowing (DAS). We believe that this is the first work on Eucalyptus in soil with residues of the herbicide indaziflam. Chlorophyll a and b contents and ETR, and height and stem dry mass of Clone I144, were lower in soil contaminated with indaziflam residues. The doses of indaziflam necessary to cause 50% (C50) of injury and the lowest height of sorghum plants were 4.65 and 1.71 g ha−1 and 0.40 and 0.27 g ha−1 in clayey soil and sand, respectively. The sorption ratio (SR) of this herbicide was 10.65 in clayey soil. The herbicide indaziflam leached up to 30 cm depth at doses of 37.5 and 75 g ha−1 and its residue in the soil reduced the levels of chlorophylls a and b, the apparent ETR and the growth of Clone I144.

A field experiment was conducted during the kharif season of 2023 at the Agricultural Research Station in Hagari, Ballari, to assess the effect of different weed management practices on the growth and yield of kharif grain sorghum. The experiment was replicated thrice in randomized complete block design comprising of eleven different treatments. According to the findings, the growth parameters like plant height (138.8 cm), number of leaves per plant (8.9), leaf area (29.1 dm2 plant-1), leaf area index (4.31) and total dry matter production (212.3 g plant-1) at harvest recorded significantly higher with the application of atrazine 50% WP @ 500 g a.i. ha-1 as PE fb metribuzin 70% WP @ 100 g a.i. ha-1 as PoE at 15-18 DAS (T7) treatment. This treatment also recorded higher grain yield (2905 kg ha-1), stover yield (8576 kg ha-1), harvest index (25.3%), gross returns (Rs. 1,19,425 ha-1), net returns (Rs. 80,988 ha-1) and B:C (3.11) when compared with other treatments. Which might be due to, application of atrazine as pre-emergent control weeds in earlier stages of crop and post-emergent application of metribuzin control weeds in later stages of crop growth. The application of atrazine and metribuzin helps in better growth of plant and obtaining the higher grain yield, net returns and B:C found economically feasible.

A field experiment was conducted during the rainy (kharif) seasons of 2011 and 2012 at Indore, Madhya Pradesh, to identify the suitable and effective integrated weed-management practices for sorghum [Sorghum bi- color (L.) Moench]. The experiment was laid out in a randomized block design replicated thrice with 10 treatments of weed-management practices on sorghum hybrid CSH 16. Mean data of 2 years indicated that all the weed- management practices significantly reduced the density and dry weight of weeds and helped in a significant en- hancement in yield attributes and yield of sorghum. Among different weed-management practices applied, pre- emergence applications of pendimethalin @ 0.50 kg a.i./ha + 1 hand-weeding at 30 days after sowing was an ef- fective practice in controlling the weeds 63.9% weed-control efficiency (WCE) and remunerative in terms of net re- turns ( 35,049/ha), followed by the application of atrazine @ 0.25 kg a.i./ha + 2 hand-weeding at 30 and 45 DAS (60.29% weed-control efficiency and net returns ( 33,548/ha). It was also observed that both the weed-manage- ment practices recorded the lower weed density and dry weight of weeds as compared to all other methods of weed control.

A field experiment was carried out during the rainy season of 2011 and 2012 in Vertisols at Dharwad, Karnataka, to develop integrated weed management for hybrid sorghum [ Sorghum bicolor (L.) Moench] with pre- emergence application of atrazine @ 0.5 kg/ha, post-emergence application of atrazine @ 0.75 kg/ha, 2, 4-D @ 0.5 kg/ha, metsulfuron methyl @ 4 g and 6 g/ha, intercultivation and hand-weeding. The maximum average grain yield (4.42 t/ha) was recorded with pre-emergence application of atrazine @ 0.5 kg/ha, followed by post-emer- gence application of 2, 4-D @ 0.75 kg/ha at 20 days after sowing and interculturing at 30 days after sowing, which was at par with weed free treatment and increased the yield by 39.8% over weedy check and 6.5% over farmers practice. The higher grain yield may be owing to significantly lower weed dry weight, higher weed-control effi- ciency and higher nutrient uptake by sorghum which reflected in higher values of grain weight/ear, ear length and 1,000-grain weight. In weedy check, weeds removed 20.5 kg N/ha, 14.9 kg P/ha and 22.3 kg K/ha, being higher than rest of the weed-management practices. Maximum net returns ( 29,530/ha) and benefit: cost ratio (2.43) were realized with atrazine @ 0.5 kg/ha (PE), followed by 2, 4-D @ 0.75 kg/ha (PoE) at 20 days after sowing and intercultivation at 30 days after sowing.

The organic nutrient and weed management practices applied in maize and their residual efficiency was seen in succeeding mustard crop in respect of weed management and productivity of mustard. Therefore, an experiment was conducted during rabi 2019- 20 and 2020-21 at College of Agriculture, Sumerpur, Rajasthan, India to see the residual impact of various weed and nutrient management practices on mustard applied in maize during preceding kharif season. The experiment was laid out in a split-plot design, with organic weed management in main plots and organic nutrient management practices in subplots. The crop was raised as residual after main crop of maize. All the treatments were applied in maize during kharif season as per prescribed treatments. The different organic weed and nutrient management treatments did not influence the weed density and weed dry matter of various categories of weeds recorded at 30 DAS. The plant height, dry matter accumulation, number of primary branches and length of silique of mustard was maximum in 100% RDN through FYM in pooled study at different growth stages of crop. This treatment also significantly increased grain (2174 kg/ha) and straw yield (5858 kg/ha) of mustard as well as net return (Rs. 68575/ha) and B:C (2.91) as against the mean minimum in 100% RDN through vermicompost. Thus, application of FYM in preceding season crop has a pronounced effect on productivity of succeeding crop while cultural and mechanical methods of weed control does not have any residual effect.

Weed management systems used by sweet corn growers, including the role of atrazine, are poorly characterized. Management records of 175 fields throughout the major sweet corn production areas of the Midwest were surveyed from 2005 to 2007. Seventy-four percent of sweet corn fields in the Midwest were grown in rotation with soybean or corn. Interrow cultivation was used on 48% of fields, and atrazine use was higher in those fields without interrow cultivation. A majority of fields (54%) received both PRE and POST herbicide applications. Mesotrione was applied below the registered use rate in two-thirds of the fields in which it was used POST. Atrazine rates in sweet corn were highest when the preceding crops were other vegetables, compared to preceding crops of soybean or corn. Selective herbicides are used extensively in U.S. sweet corn production, accounting for 94% of total weed management expenditures which average $123/ha. Growers treated 66% of fields with one or more applications of atrazine at an average total use rate of 1.35 kg ai/ha. The estimated annual net cost to replace atrazine in U.S. sweet corn production with the broad spectrum broadleaf herbicide, mesotrione, is $9.2 million.

Dentre as práticas que visam conferir sustentabilidade do solo agrícola, o emprego de adubos verdes e/ou plantas de cobertura como a crotalária tem sido preconizado. O manejo de plantas daninhas é uma das práticas para o sucesso da crotalária. Entretanto, as informações sobre a seletividade de herbicidas são escassas, sendo estas de suma importância. Assim, objetivou-se avaliar a seletividade de herbicidas aplicados em pós-emergência da crotalária (Crotalaria spectabilis). Foram realizados dois experimentos em casa de vegetação no delineamento inteiramente casualizado, com quatro repetições. No primeiro foram testados os seguintes herbicidas (g ha-1 i.a.): atrazine (500 e 1000), bentazon (720), carfentrazone-ethyl (3,75), clomazone (400), diclosulam (20), diuron (800), ethoxysulfuron (18), flumioxazin (10), mesotrione (60), oxadiazon (500), tembotrione (40), atrazine + flumioxazin + carfentrazone-ethyl (300 + 5 + 2), e uma testemunha sem aplicação. No segundo aplicou-se: bentazon (400), clomazone (400), diclosulam (10 e 15), diuron (400), ethoxysulfuron (15), bentazon + diclosulam (200 + 7,5), diclosulam + diuron (7,5 + 200), bentazon + diuron (200 + 200), e uma testemunha sem aplicação. Foram realizadas avaliações de fitotoxicidade aos 7, 14, 21 e 28 dias após a aplicação (DAA) e de matéria seca da parte aérea (MSPA) aos 28 DAA. Em ambos os experimentos os herbicidas bentazon, clomazone, diclosulam e ethoxysulfuron causaram baixa fitotoxicidade à cultura e baixa redução na MSPA. Os herbicidas atrazine, mesotrione, oxadiazon e atrazine + flumioxazin + carfentrazone-ethyl proporcionaram altos níveis de intoxicação e alta redução na MSPA. Os herbicidas bentazon, clomazone, diclosulam e ethoxysulfuron foram seletivos para aplicação em pós-emergência da cultura.

The effect of herbicides and weeds on the yield and composition of dill ( Anethum graveolens L.) oil

Kapanigowda, M., H., Perumal, R., Aiken, R. M., Herald, T. J., Bean, S. R. and Little, C. R. 2013. Analyses of sorghum [ Sorghum bicolor (L.) Moench] lines and hybrids in response to early-season planting and cool conditions. Can. J. Plant Sci. 93: 773–784. Early-season cold tolerance in sorghum contributes to emergence, seedling establishment, and early vegetative growth, and reduces damping-off diseases under chilling conditions. The objectives of this study were to identify cold-tolerant sources and to evaluate and optimize rapid screening techniques under a controlled environment. Field studies involving 48 genotypes, representing phases of the hybrid development process (landraces, elite and advanced breeding lines, recombinant inbred lines (RILs) and hybrids were conducted with early and normal planting dates in 2011 at Hays and Colby, Kansas. Studies under controlled environments were conducted at both locations using 18 genotypes that differ for emergence index (EI) and 30 d after emergence (DAE) shoot biomass based on field studies during 2011. Significant differences among the genotypes were recorded for all seedling traits (emergence percentage, EI, shoot biomass, plant height, and leaf number measured 30 DAE), and agronomic traits (days to 50% flowering, panicle exsertion, panicle length, and plant height at maturity). Eight advanced breeding lines: ARCH10731, ARCH10732, ARCH10736, ARCH10737, ARCH10738, ARCH10739, ARCH10744 and ARCH10749 and one RIL (RTx430/SQR-2) were found to be potential sources of cold tolerance with early EI, higher biomass and relatively early flowering. These genotypes are free from tannin, which helps to increase the feed grain efficiency of livestock, and hence were selected for test hybrid evaluation to assess fertility status, combining ability and yield performance. Significant correlation was observed between EI and biomass during early planting, which indicated that late-emerging genotypes produced greater biomass (30 DAE) compared with early-emerged genotypes. Significant correlation between growth chamber and field study for EI offers a potential and fast preliminary high-throughput screening technique for identification of cold-tolerant sorghum.

Estudios previos han demostrado que el sorgo [Sorghum bicolor (L.) Moench] se puede cultivar a escala comercial con éxito en áreas de la costa sur de Puerto Rico. Esto significa que puede ser un cultivo altemo y una manera de reducir la importación de grano para concentrado, que sobrepasa las 200,000 toneladas anuales, provenientes de los Estados Unidos y otros países con un valor de $16.0 millones. Se determinó el potencial de rendimiento y comportamiento agronómico de 10 híbridos de sorgo (siete de grano rojo y tres de grano blanco) en la subestación Experimental Agrícola de Fortuna, municipalidad de Juana Díaz. El experimento se sembró el 5 de mayo de 1993 y 23 de mayo de 1994 utilizando un diseño de bloques al azar con parcelas divididas con tres replicaciones. La parcela experimental consistió de tres hileras donde la hilera central se utilizó para obtener datos de rendimiento y de otras características. En promedio los 10 híbridos produjeron 5,020 kg/ha. El híbrido de mayor rendimiento fue el Cargill Ma Cau 90 con una producción de 6,240 kg/ha, significativamente mayor que la de los demás híbridos, excepto DK-65. El híbrido Cargill Appolo fue el de menor rendimiento. Los valores promedio para otros caracteres agronómicos fueron días a mitad de florecida, 63.9 días; altura de la planta, 150.4 cm; peso de 100 semillas, 3.44 g; índice de cosecha, 31%. Además, se encontró una correlación significativa (r = 0.34) entre altura de la planta y rendimiento de grano. El rendimiento demuestra que algunos de estos híbridos tienen potencial para ser sembrados a escala comercial y ayudar a reducir la dependencia de Puerto Rico en la importación de granos para concentrado de animales.