Avoid Yield Loss Research Articles

Avoidable yield losses caused by major insect pests on okra

Avoidable yield losses caused by major insect pests on okra

Assessment of avoidable yield losses due to major pests of lentil in Eastern India

Assessment of avoidable yield losses due to major pests of lentil in Eastern India

Assessment of Yield Losses due to Meloidogyne incognita on Cucumber (Cucumis sativus L.)

The experiment was carried out in the field of Department of Nematology Odisha University of Agricultural and Technology, Bhubaneswar during the rabi, 2021–2022 to estimate the avoidable yield losses in 12 Patra variety of cucumber due to root-knot nematode, Meloidogyne incognita in nematode infested field. Ten replications of the experiment were set up using the paired plot technique. Required quantity of Carbofuran granules@2kg a.i./ha was applied two days before sowing. Ten plots were treated and another ten plots were kept untreated control (without carbofuran application). The findings exhibited that application of carbofuran significantly reduced the number of galls, egg masses and nematode population -80.01, -84.49, -27.23 respectively. Avoidable yield losses were recorded to the tune of 66.23 percent on cucumber plants by M. incognita.

Characteristics of Extreme Precipitation and Their Effect on Bean Yield in Rwanda

This study examines the characteristics of extreme precipitation and its effect on bean yield in Rwanda from 1981 to 2017. Over the study area, two rainy seasons, March to May (MAM) and September to December (SOND), account for approximately 80% of total rainfall. The spatial distribution of rainfall over Rwanda revealed that the first three EOF modes of MAM rainfall vary by 72.72 percent over the study period, while the first three EOF modes of SOND rainfall vary by 57.48 percent. The spatial analysis of extreme precipitation reveals that during wet years, the majority of the country's western regions receive significantly more precipitation than the rest. Throughout the study period, the analysis revealed an increasing trend in all extreme precipitation indices. After 2009, a significant increase in the number of wet days (R1mm) and consecutive dry days (CDD) was observed, as was an increase in the number of consecutive wet days (CWD) after 2005. From 1981 to 1989, bean yield increased; however, after 1990, the trend became stationary and began to decline after 2012. Except for R1mm, CDD, and CWD, which showed a negative correlation, the correlation analysis revealed a positive relationship between extreme precipitation indices and bean yield. Despite the fact that there is a weak negative correlation between bean yield and CDD, CDD can be used as a predictor of bean yield due to the significant Granger causality test at the 95% confidence level. Farmers are advised to use alternative methods to increase soil moisture and water holding capacity during the CDD period to avoid yield loss.

Impact of Stripe Rust on Yield Loss of Wheat and Its Status In Haryana, India

Stripe rust caused by Puccinia striiformis f. sp. tritici (Pst) is a major constraint in all wheat-growing countries. Surveys conducted during 2015-19 in Haryana, maximum stripe rust severity recorded in Yamuna Nagar (28.57%) followed by Ambala (23.33%) and least observed in Fatehabad (5%).Two commonly prevalent pathotypes 46S119 and 110S119 were in all 4 crop seasons followed by 238S119 occurrence in two seasons. Infection range was 0-80S in varieties HD2967, Shri Ram152, Shri Ram171, Shri Ram3132, Barbett, WH147 and HD2851. Maximum terminal disease severity contracted by WH 147 (100%), HD2967 (100%) and PBW 343(96.66 %) in seedling stage disease appearance followed by tillering stage and least disease severity was observed on milk development. Stripe rust symptoms produced 14 days after artificial inoculation with urediniospores (106/ml) of Puccinia striiformis f. sp. tritici. Maximum avoidable yield loss was obtained in WH 147 (73.14%) followed by HD2967 (68.35%), PBW343 (60.08%) and least recorded in WH1105 (20.26%) on seedling stage. Minimum yield loss in varieties was recorded at milk development stage. There was significant correlation (0.90) between disease severity and avoidable yield loss with the coefficient of determinant, R2= 0.80. Bangladesh J. Bot. 51(4): 647-653, 2022 (December)

Irrigation modulates the effect of increasing temperatures under climate change on cotton production of drip irrigation under plastic film mulching in southern Xinjiang.

Warming and drought brought about by climate change seriously harm sustainable agricultural production in southern Xinjiang. It is still unclear how irrigation can improve the ability of crops to cope with climate change. Therefore, in this study, we calibrated and validated the AquaCrop model using data collected in cotton production from 2017 to 2018. The model effectively simulated the growth, biomass, and yield of cotton plants at the experimental site under different warming and irrigation conditions. The meteorological data collected from 1987 to 2016 were used in a simulation to predict cotton production under 3 temperature scenarios (temperature increased by 0°C, 1°C, and 2°C) and 6 levels of irrigation (198, 264, 330, 396, 495, and 594mm) to explain the modulating effect of plastic film mulching-coupled drip irrigation on cotton production in terms of increasing temperatures under climate change in southern Xinjiang. Model prediction showed that an increase in temperature reduced cotton yield under a low irrigation level, while an increase in irrigation mitigated the impact of climate change on cotton yield. An increase of 1°C did not significantly reduce cotton yield at 198-330 mm of irrigation. Under a 2°C increase, 396-594 mm of irrigation was required to ensure plant growth and yield formation. Both aboveground biomass and yield increased with the rise in the irrigation level at the same temperature. High water use efficiency was achieved at 495mm of irrigation without significant yield loss. Therefore, in the low-temperature scenario, it can be preferentially considered to achieve sustainable water use through water management, while in the high-temperature scenario innovative agricultural measures are required to avoid yield loss. Optimizing irrigation strategies can reduce warming-induced damage to crops under climate change.

LCHC-DFT: A Low-Cost High-Coverage Design-for-Testability Technique to Detect Hard-to-Detect Faults in STT-MRAMs in the Presence of Process Variations

This paper proposes a low-cost yet high-coverage design-for-testability (DFT) scheme for improving the detection of hard-to-detect (HtD) faults in STT-MRAMs. It is based on introducing a voltage mismatch in the sense amplifier (SA). This mismatch along with the defects in the cell may bias the SA, leading to an incorrect read output which in turn make the HtD faults detectable. The efficacy of the proposed scheme is evaluated by calculating its detection capability in the presence of resistive defects. Evaluation results obtained for a 20nm STT-MRAM memory design show that the proposed scheme provides HtD fault coverage of 81.8% and 86.5%, on average, for intra-cell and inter-cell defects, respectively, with a negligible area overhead (1.1% for a 2Kbit array). In comparison with conventional March tests, which only detect easy-to-detect (EtD) faults, the proposed DFT technique covers both HtD and EtD faults with a faster approach, namely by using a single read operation. Furthermore, to guarantee that the cells affected by HtD faults trigger an incorrect read output under process variation (PV), a timing strategy based on modifying the control unit of the proposed DFT is suggested. The strategy controls the stress introduced by the DFT unit by altering the timing of DFT control signals. The timing alteration enables the detection of HtD faults in the devices with higher deviations from the nominal one due to PV, avoiding yield loss or test escapes.

Bt maize can provide non-chemical pest control and enhance food safety in China.

China is the world's second-largest maize producer and consumer. In recent years, the invasive fall armyworm Spodoptera frugiperda (J.E. Smith) has adversely affected maize productivity and compromised food security. To mitigate pest-inflicted food shortages, China's Government issued biosafety certificates for two genetically modified (GM) Bt maize hybrids, Bt-Cry1Ab DBN9936 and Bt-Cry1Ab/Cry2Aj Ruifeng 125, in 2019. Here, we quantitatively assess the impact of both Bt maize hybrids on pest feeding damage, crop yield and food safety throughout China's maize belt. Without a need to resort to synthetic insecticides, Bt maize could mitigate lepidopteran pest pressure by 61.9-97.3%, avoid yield loss by 16.4-21.3% (range -11.9-99.2%) and lower mycotoxin contamination by 85.5-95.5% as compared to the prevailing non-Bt hybrids. Yield loss avoidance varied considerably between experimental sites and years, as mediated by on-site infestation pressure and pest identity. For either seed mixtures or block refuge arrangements, pest pressure was kept below established thresholds at 90% Bt maize coverage in Yunnan (where S. frugiperda was the dominant species) and 70% Bt maize coverage in other sites dominated by Helicoverpa armigera (Hübner) and Ostrinia furnacalis (Guenée). Drawing on experiences from other crop/pest systems, Bt maize in se can provide area-wide pest management and thus, contribute to a progressive phase-down of chemical pesticide use. Hence, when consciously paired with agroecological and biodiversity-based measures, GM insecticidal crops can ensure food and nutrition security, contribute to the sustainable intensification of China's agriculture and reduce food systems' environmental footprint.

Weed control and sustainable rice production through rice intensification system and conventional practices of weed competition periods and age of transplanted seedlings

Rice is an important cereal crop of global interest based on its daily uses. It was observed that the average yield of rice is low than its potential production due to the traditional growing techniques and weed intensification. Recently, the rice intensification system (RIS) has emerged as an alternative to the conventional rice cultivation system. A two-year field study was carried out to investigate the impact of seedling age (14, 21 & 28 days) and the weed competition periods (weedy check, 20, 40, 60, 80 DAT and weed-free throughout the growing season) in rice cultivated through RIS. Weedy check and weed-free for the growing season were kept as a control treatment. The results of our study revealed that a maximum dry weight (108.7 and 111.79 gm-2) and weeds density (101.7 and 110.6 plants m-2) of weed recorded in weedy check plot where 28 days old seedlings was transplanted while minimum dry weight (11.01 and 10.3 gm-2) and weeds density (9.7 and 10.9 m-2) were achieved in plots where 21 days old seedlings were transplanted and remain weed free. It was noted that weed density and weed dry biomass were gradually increased with increasing weed competition period at all ages of the rice seedling. Purple nutsedge (C. rotundus) exhibited maximum relative proportion in total weed’s density and dry biomass and also ranked first by weed summed dominance ratio (WSDR). Agronomic yield and yield contributing traits such as number of fertile tillers per hills (58.1 and 56.0), plant height (130.5 cm and 125.6 cm), kernels per plant (186.4 and 179.4), straw yield (7.8 t ha-1 and 7.5 t ha-1) and kernel yield (5.2 and 5.0 t ha-1) were maximum in plot that remained weed-free throughout the growing season with a seedlings age of 21 days during 2010 and 2011 respectively. Percent yield losses were minimum in plots with 21 days old seedling transplantation and at 20 days of weed competition period. Hence, present study concludes that 21 days old fine rice seedlings should be transplanted and weeds should be controlled within 20 DAT under SRI for effective weed control to avoid yield losses.

Progress and prospectus in genetics and genomics of Phytophthora root and stem rot resistance in soybean (Glycine max L.)

Soybean is one of the largest sources of protein and oil in the world and is also considered a "super crop" due to several industrial advantages. However, enhanced acreage and adoption of monoculture practices rendered the crop vulnerable to several diseases. Phytophthora root and stem rot (PRSR) caused by Phytophthora sojae is one of the most prevalent diseases adversely affecting soybean production globally. Deployment of genetic resistance is the most sustainable approach for avoiding yield losses due to this disease. PRSR resistance is complex in nature and difficult to address by conventional breeding alone. Genetic mapping through a cost-effective sequencing platform facilitates identification of candidate genes and associated molecular markers for genetic improvement against PRSR. Furthermore, with the help of novel genomic approaches, identification and functional characterization of Rps (resistance to Phytophthora sojae) have also progressed in the recent past, and more than 30 Rps genes imparting complete resistance to different PRSR pathotypes have been reported. In addition, many genomic regions imparting partial resistance have also been identified. Furthermore, the adoption of emerging approaches like genome editing, genomic-assisted breeding, and genomic selection can assist in the functional characterization of novel genes and their rapid introgression for PRSR resistance. Hence, in the near future, soybean growers will likely witness an increase in production by adopting PRSR-resistant cultivars. This review highlights the progress made in deciphering the genetic architecture of PRSR resistance, genomic advances, and future perspectives for the deployment of PRSR resistance in soybean for the sustainable management of PRSR disease.

Digital gene expression profiling of the transcriptional response to Sclerotinia sclerotiorum and its antagonistic bacterium Bacillus amyloliquefaciens in soybean.

Soybean Sclerotinia stem rot caused by Sclerotinia sclerotiorum is a common disease in soybean, and effective biological control is urgently needed. We have previously confirmed that Bacillus amyloliquefaciens can effectively antagonize S. sclerotiorum in a plate competition experiment and a soybean seedling inoculation experiment. In this study, the mechanisms underlying plant death caused by S. sclerotiorum and soybean resistance to S. sclerotiorum induced by B. amyloliquefaciens were evaluated. The stems of potted soybean seedlings were inoculated with S. sclerotiorum (Gm-Ss), B. amyloliquefaciens (Gm-Ba), and their combination (Gm-Ba-Ss), using scratch treatments as a control, followed by dual RNA sequencing and bioinformatics analyses. Global gene expression levels in the Gm-Ss treatment were much lower than those in the Gm-Ba, Gm-Ba-Ss, and Gm groups, suggesting that S. sclerotiorum strongly inhibited global gene expression in soybean. In a pairwise comparison of Gm-Ss vs. Gm, 19983 differentially expressed genes (DEGs) were identified. Down-regulated DEGs were involved in various KEGG pathways, including ko01110 (biosynthesis of secondary metabolites), ko01100 (metabolic pathways), ko01120 (microbial metabolism in diverse environments), ko00500 (starch and sucrose metabolism), and ko04075 (plant hormone signal transmission), suggesting that S. sclerotiorum inoculation had a serious negative effect on soybean metabolism. In Gm-Ba vs. Gm, 13091 DEGs were identified, and these DEGs were significantly enriched in ko03010 (ribosome) and ko03008 (ribosome biogenesis in eucaryotes). Our results suggest that B. amyloliquefaciens increases the expression of genes encoding the ribosomal subunit, promotes cell wall biogenesis, and induces systemic resistance. S. sclerotiorum strongly inhibited metabolism in soybean, inhibited the synthesis of the cytoskeleton, and induced the up-regulation of programmed death and senescence-related genes via an ethylene signal transduction pathway. These results improve our understanding of S. sclerotiorum-induced plant death and soybean resistance to S. sclerotiorum induced by B. amyloliquefaciens and may contribute to the improvement of strategies to avoid yield losses.

Response of turmeric to saline water irrigation on growth, physiology, antioxidant defence mechanism and productivity

Aim: The aim of the present study was to study the effect of saline water irrigation on growth, physiology, biochemical signal and economic yield of turmeric. Methodology: Pot experiment was conducted with five salinity levels (0 dSm-1, 2 dSm-1, 4 dSm-1, 6 dSm-1 and 8 dSm-1) replicated four times in RCBD. Salinity level were prepared using NaCl, CaCl2, MgCl2 and MgSO4 to maintain Cl:SO4 ratio in 7:3. Salinity treatments were imposed according to treatment scheduled 30 day after transplanting of seedling and continued till crop maturity. In each pot 2 l of saline water was applied at 10 days interval according to the treatment. The control plants were irrigated with equal amount of distilled water. Observations on morphological, chlorophyll, canopy temperature, Normalized difference in vegetative index, phenol and protein content Ascorbate peroxidase, Superoxide dismutase and yield parameters were recorded. Results: The results showed that irrigation with saline water induced changes in growth and yield parameters in turmeric crop. Plant height at different levels of salinity stress was affected significantly, the lowest (37.9cm) plant hight was observed at 8 dSm−1 salinity. A slight increase in salinity by 2 dsm-1 reduced the growth of turmeric by 15.7% as compared to control. Number of tillers, leaves per plant and leaf area was also significantly reduced. With increase in salinity levels, the chlorophyll and NDVI of leaves were reduced. The lowest fresh rhizome yield (19.8 g per plant) was recorded at 8 dSm−1 and in turn, it resulted in the lowest dry yield (2.5 g per plant) and dry recovery (12%). Interpretation: Salinity is highly detrimental to turmeric crop and leads to drastic reduction in growth, yield and productivity by reducing physiological and biochemical functions. Thus, the use of saline water in irrigation should be carefully looked inorder avoid yield loss. Key words: Chlorophyll, Dry recovery, Membrane stability, Salinity, Turmeric

Enhanced Prediction of Diseases in plants using Machine Learning and Climatology

Automatic prediction of diseases in plants is a challenging task with technology intervention. In addition, proper maintenance of plant growth requires several steps, including research on environmental factors and management of water supply for proper plant growth. Traditional irrigation procedures stay inefficient additionally unpredictable. Every year, about 18% of the yield is lost to pests around the world. Identifying plant viruses remain the key to avoiding yield losses on agricultural products that are difficult to do manually. This paper presents an architecture that allows users to perform prediction of plant diseases using machine learning and climatology based data in real time, allowing farmers to view farm details automatically without manual intervention. Disease detection of visually visible symptoms of plants using image processing is proposed and treatment to reduce the level of damage is proposed to farmers. Therefore, the proposed system will increase productivity and benefit the irrigation sector. The main problem facing farmers in agriculture is the lack of water due to the effective irrigation separators on small farms. However, this technique consumes several weaknesses that can be improved, a method called the Automatic Irrigation System with weather forecasts for the efficient use of water resources. This overcomes the shortcomings of the AISPF process. The method uses available aquatic assets extra capacity by measuring atmospheric pressure, or barometric pressure (in inches), apart from measuring the water present-day in the topsoil and actually predicting the weather. This system uses a soil moisture sensor and a pneumatic sensor for performing measurements to be processed by the algorithm and water is discharged accordingly. This enables efficient use of water automatically. The system provides better accuracy than state of the art techniques for plant disease prediction and water flow control, which could be useful for irrigation.

Estimation of crop loss caused by important insect-pests of mango

A field experiment was conducted at Regional Horticultural Research Station, ASPEE College of Horticulture and Forestry, Navsari Agricultural University, Navsari (Gujarat) during 2009-10 to 2010-11. Application of recommended as well as need based insecticides in protected plots resulted in significantly lower hoppers (3.95 hoppers/twig or panicle), thrips (5.47 thrips/twig or panicle), damages of leaf gall midge (7.24% leaf damage), leaf webber (3.54 web/tree) and fruit fly (7.86% fruit infestation) as compared to the unprotected plots. Number of fruits set at stone (378.54/tree) and harvest stages (232.25/tree) were higher in protected trees giving significantly higher yield in protected (58.06 kg/tree) over untreated (21.82 kg/tree) trees followed by significant lower fruit dropping (38.51%) in the former over the latter (50.58%). The avoidable yield losses due to insect-pests was to the tune of 61.51% resulting into net profit of Rs. 69,780/ ha. in protected trees over control.

Fixing critical limits of boron in rice soils of Karaikal region, Puducherry union territory, India

Boron is relatively immobile in plants and its deficiency can cause serious yield reduction in rice by retarding panicle formation. Karaiakal region of Puduchuerry union terittory includes different soils with varying fertility status thus supplying boron at optimum level is a must concern to enhance the rice productivity.A pot experiment was conducted to fix critical limits of boron in soils and rice of this Karaikal region. Forty surface soil samples (0-15 cm) were collected from Inceptisol, Entisol and Vertisol soil orders of different locations in Karaikal region. The experiment was conducted with three levels of boron viz., 0, 1 and 2 ppm applied through borax in a factorial completely randomized design with three replications. The available B content of soil was estimated with five extractants. The critical limits of hot water, hot 0.01 M CaCl2, 0.05 M HCl, 1.0 M NH4OAc, 0.01M CaCl2+ 0.05 M Mannitol extractable B were found to be 0.50, 0.58, 0.46, 0.45 and 0.39 ppm in Inceptisol, 0.48, 0.59, 0.44, 0.39 and 0.48 ppm in Entisol and 0.45, 0.54, 0.45, 0.44 and 0.41ppm in Vertisol and a critical limit of 31.0, 39.0 and 34.0 ppm B in rice plant for Inceptisol(0.5ppm), Entisol(0.48 ppm) and Vertisol(0.45 ppm) as determined by Cate and Nelson’s graphical procedure. Among the extractants the hot water extractant showed the highest significant and positive correlation with Bray’s percent yield(0.48,0.47and 0.48), plant B content(0.041*, 0.019* and 0.271*) and B uptake(0.012*, 0.646* and 0.293*), respectively in Inceptisol, Entisol and Vertisol. From this study, the indicating knowledge of critical limit of boron will help to avoid yield loss of rice in the study region.

Juvenile heat stress tolerance in Triticum durum-Aegilops tauschii derived synthetics: a way forward for wheat improvement.

Exponentially increasing population and everchanging climatic conditions are two major concerns for global food security. Early sowing in the second fortnight of October is an emerging trend with farmers in Indo Gangetic Plains to avoid yield losses from terminal heat stress. This also benefits the use of residual soil moisture of rice crop, conserving about one irrigation. But most of the available wheat cultivars are not well adapted to early-season sowing. Two in-house developed SHWs, syn14128 and syn14170, were screened for juvenile heat stress. Seedling length, biochemical parameters, and expression of amylase gene immediately after heat shock (HS) of 45°C for 12h and 20h, and 24h indicated significantly lower malondialdehyde, hydrogen peroxide, and higher free radical scavenging activities. Syn14170 reported higher total soluble sugar (TSS) under both HS periods, while syn14128 had a sustainable TSS content and amylase activity under HS as well as the recovery period. Both the SHWs had lower oxidative damage along with high free radical scavenging under heat stress. The higher expression of amy4 along with sustainable TSS after heat stress in syn14128 indicated it as a potential source of juvenile heat stress tolerance. Variable response of SHWs to different biochemical parameters under heat stress opens future perspectives to explore the enzymatic pathways underlying these responses.

A review of approaches to control bacterial leaf blight in rice.

The Gram-negative bacteria Xanthomonas oryzae pv. oryzae, the causative agent of bacterial leaf blight (BLB), received attention for being an economically damaging pathogen of rice worldwide. This damage prompted efforts to better understand the molecular mechanisms governing BLB disease progression. This research revealed numerous virulence factors that are employed by this vascular pathogen to invade the host, outcompete host defence mechanisms, and cause disease. In this review, we emphasize the virulence factors and molecular mechanisms that X. oryzae pv. oryzae uses to impair host defences, recent insights into the cellular and molecular mechanisms underlying host-pathogen interactions and components of pathogenicity, methods for developing X. oryzae pv. oryzae-resistant rice cultivars, strategies to mitigate disease outbreaks, and newly discovered genes and tools for disease management. We conclude that the implementation and application of cutting-edge technologies and tools are crucial to avoid yield losses from BLB and ensure food security.

Comparison of exemplary crop protection strategies in Swiss apple production: Multi-criteria assessment of pesticide use, ecotoxicological risks, environmental and economic impacts

Plant protection products (PPP) are used to protect apples from pests and diseases and to maintain high yields and fruit quality. Alternatively, non-chemical plant protection measures can be applied to reduce the use and ecotoxicological risks of PPP. However, additional materials, energy or labor are needed, which can have an impact on the environmental or economic performance. To investigate possible trade-offs, this multi-criteria analysis examined different apple production systems based on exemplary crop protection strategies in Switzerland. One integrated crop protection strategy complying with the Swiss Proof of Ecological Performance (PEP2018) was used as a reference, and three exemplary strategies were compared to this reference. The integrated «PPP Reduced» strategy assumed a minimal use of synthetic PPPs in combination with a range of alternative plant protection measures to avoid yield losses. The conventional «High yield» strategy assumed maximum yields with minimal restrictions on the use of synthetic PPPs and fertilizer. Finally, the «Organic» strategy represented typical organic apple production without the use of synthetic PPPs. To compare the performance of these strategies, 13 indicators were calculated, covering four aspects. PPP use was analyzed with the treatment frequency index, local ecotoxicological risks for next-to-field habitats were modeled with SYNOPS, global environmental impacts of 1 kg apple were analyzed with life cycle assessment (LCA) and economic impact on farms was assessed with a full-cost calculation. Compared to the «PEP2018» strategy, the «PPP Reduced» strategy performed much better in terms of ecotoxicological risks and biodiversity, but was not profitable due to high investments resulting in a negative farmer's hourly wage. The ecotoxicological risks were comparable between the «PEP2018» and «High yield» strategies, with the latter performing much worse in terms of biodiversity and global warming potential. Despite the high capital and labor input, the «High yield» strategy was much better in terms of resource use and farmer's hourly wage. The «Organic» strategy had the largest impact (per kg of apples) on most global environmental indicators, but performed much better on ecotoxicological risks and also on farmer's hourly wage. The results of this study show that reducing the use of PPP and the associated risks in apple orchard without environmental or economic compromises is challenging. None of the strategies examined performed better than the other strategies in all indicators assessed. However, this approach could contribute to identify and design more sustainable crop protection systems in apple production.

Assessment of Yield Losses Due to Sucking Pests in BT cottton

Field experiment was conducted during kharif 2019 to determine the avoidable yield losses due to sucking insect pests on four cotton cultivars BG II (US 81& RCH 776), non Bt F-2228 and Desi LD 949 at two sowing dates (timely-25th April; and late 27th May) at the Punjab Agricultural University, Ludhiana. Significantly higher incidence of whitefly Bemisia tabaci (Genn.) (20.61 adults), jassid Amrasca biguttula biguttula (Ishida) (12.97 nymphs) and thrips Thrips tabaci (Lindeman) (7.32 adults/ 3 leaves) was observed under late sown conditions, compared to the timely sown one with less incidence- B. tabaci (14.51 adults), A. biguttula biguttula (11.37 nymphs) and T. tabaci (6.58 adults)/ leaves. Significantly less B. tabaci (16.69 adults), A. biguttula biguttula (13.74 nymphs) and T. tabaci (5.86 adults) were observed with desi cotton (LD 949) as compared BG II cultivars (RCH 776, US 81) and non Bt F 2228. Significantly less avoidable yield loss (16.41%) was observed with timely sown crop as compared to 18.45% losses under late sown conditions. Significantly less yield loss was observed in desi cotton (16.01%) as compared to US 81 (16.55%), RCH 776 (17.20) and F 2228 (19.98%).

​Pathogenicity of Root Knot Nematode (Meloidogyne incognita) and its Effect on Yield of Cowpea [Vigna unguiculata (L.) Walp

Background: Cowpea [Vigna unguiculata (L.) Walp.] is an important food legume in the drier region and an essential component of the tropics and subtropics for the cropping system. Heavy infestation of cowpea by root knot nematode Meloidogyne incognita led to early senescence of the crop. The experiment was carried out to determine the potential level and the extent of yield loss in cowpea due to root knot nematode. Methods: A pot culture study and a field experiment were conducted to determine pathogenic potential level of root knot nematode and to determine the yield loss in cowpea with various treatment of 10, 100, 1000 and 10000 freshly hatched juveniles. Result: The treatment with nematicide, Carbofuran 3G @ 3 kg a.i./ha, reduced the final nematode population i.e., 50.94% in soil, 46.12% on root and 46.51% decrease in root knot index. The present study revealed that 1000 J2/pot was the ETL level that reduced all the growth parameters of cowpea and avoidable yield loss of 15.78% was recorded in Ccowpea due to M. incognita.