Varietal Mixtures Research Articles

Mix and manage: Cultivar mixtures can maintain yield under high wheat blast disease pressure

Originating in South America, wheat blast disease has spread to both Asia and Africa and is considered a significant threat to food security. Bangladesh experienced the first outbreak of wheat blast outside of the Americas in 2016. Shortly thereafter, the blast-resistant variety BARI Gom 33 was released. Seeds of this variety are however not as widely available as required, although the disease threat remains. While varietal mixtures have been shown to mitigate some symptoms and yield losses associated with other fungal diseases in wheat, there is a complete research gap on this topic as it pertains to wheat blast. As such, we evaluated the potential of using BARI Gom 33 as a component of a variety mixture under high disease pressure in Bangladesh. During three cropping seasons, blast symptoms and yield were determined in a field experiment for the highly blast-susceptible variety BARI Gom 26, the moderately susceptible BARI Gom 30, the resistant BARI Gom 33, and seven mixture combinations of the three varieties using artificial inoculation to increase disease pressure. In addition to wheat blast, Bipolaris leaf blight (BpLB) symptoms were observed and evaluated. While yields of the susceptible varieties were severely affected by blast even after fungicide application, disease-inflicted yield loss without fungicide was only 15% for sole BARI Gom 33 and did not differ significantly from yield losses in BARI Gom 33 and BARI Gom 30 mixtures. Furthermore, in the mixture containing 67% BARI Gom 33 and 33% BARI Gom 30, blast incidence and severity were reduced by 25% and 16%, respectively, in comparison to weighted values in sole stands. Conversely, mixing varieties tended to increase the symptoms of BpLB. Under high wheat blast pressure, fungicide protection against blast was relatively weak, underscoring the importance of resistant varieties. Although variety mixtures did not increase yield, the yield advantage of BARI Gom 33 was maintained when its seeds were mixed with the less resistant BARI Gom 30. This study confirms recommendations that farmers should use BARI Gom 33 as a first line of defense against wheat blast in Bangladesh. Yet where farmers cannot access sufficient BARI Gom 33 seed for planting, our data suggest that agricultural extension services can recommend this variety with non-resistant cultivars as interim strategy without significant risk of yield loss.

Effects of environmental factors and storage periods on sesame seed quality and longevity

AbstractSesame is one of the world’s oldest oil seed crops grown mainly for its seeds. Lengthened storage time, inappropriate staking, back warded threshing method and poor storage facilities are major causes for postharvest and quality losses of sesame seed. Therefore, the objective was to review the effect of storage time and storage conditions on sesame seed quality and longevity. Seed quality and longevity are mostly governed by moisture content, temperature, humidity, storage period, pre-storage conditions, and pest infestations. Moisture content is a pre-requisite for long-term seed storage, and is the most important factor affecting seed longevity. Sesame seeds remain consistent and viable up to 12 months under appropriate storage facilities and conditions, otherwise it get lessened its viability. The crop should be harvested at the appropriate time and seeds should be stored at 6% or lower moisture content. In the tropics where temperature is as high as 33 °C and relative humidity of about 80%, seeds deteriorate rapidly. Varietal mixtures and harvest conditions affect longevity of seeds in storage. Pests such as, Mites, Indian mealy moth, Weevils, Flour beetles, are serious problems in stored sesame seeds. Under low seed moisture content and temperature, insects may not be a problem. Oil seeds require high-quality constructions to prevent leakages and to allow easy access to the bin for sampling and monitoring. Therefore, sesame seeds should be stored in well-constructed room/ware house to maintain seed viability and longevity.

Upland rice varietal mixtures in Madagascar: evaluating the effects of varietal interaction on crop performance.

Rice plays a critical role in human livelihoods and food security. However, its cultivation requires inputs that are not accessible to all farming communities and can have negative effects on ecosystems. simultaneously, ecological research demonstrates that biodiversity management within fields contributes to ecosystem functioning. This study aims to evaluate the mixture effect of four functionally distinct rice varieties in terms of characteristics and agronomic performance and their spatial arrangement on the upland rice performance in the highlands of Madagascar. The study was conducted during the 2021-2022 rainfall season at two close sites in Madagascar. Both site differ from each other's in soil properties and soil fertility management. The experimental design at each site included three modalities: i) plot composition, i.e., pure stand or binary mixture; ii) the balance between the varieties within a mixture; iii) and for the balanced mixture (50% of each variety), the spatial arrangement, i.e., row or checkerboard patterns. Data were collected on yields (grain and biomass), and resistance to Striga asiatica infestation, Pyricularia oryzea and bacterial leaf blight (BLB) caused by Xanthomonas oryzae-pv from each plot. Varietal mixtures produced significantly higher grain and biomass yields, and significantly lower incidence of Pyricularia oryzea compared to pure stands. No significant differences were observed for BLB and striga infestation. These effects were influenced by site fertility, the less fertilized site showed stronger mixture effects with greater gains in grain yield (60%) and biomass yield (42%). The most unbalanced repartition (75% and 25% of each variety) showed the greatest mixture effect for grain yield at both sites, with a strong impact of the varietal identity within the plot. The mixture was most effective when EARLY_MUTANT_IAC_165 constituted 75% of the density associated with other varieties at 25% density. The assessment of the net effect ratio of disease, an index evaluating the mixture effect in disease reduction, indicated improved disease resistance in mixtures, regardless of site conditions. Our study in limited environments suggests that varietal mixtures can enhance rice productivity, especially in low-input situations. Further research is needed to understand the ecological mechanisms behind the positive mixture effect.

Mixing effects and yield performance of rice varietal mixture (VarMix) in selected areas in the Philippines

Research around the world has established the good performance of the varietal mixture (VarMix) approach in mitigating the ill effects of biotic stresses on various crops. Thus, the efficiency of this approach against abiotic stresses is also being studied. In the Philippines, the evaluation of VarMix is limited especially in large rice areas that experience water scarcity and unpredictable occurrence of pests and diseases. In this study, yield performances of 12 VarMix combinations and their corresponding single varieties were evaluated in 12 environments nationwide that suffer from water scarcity. VarMix ADCEF yielded highest at 7.7t/ha. Analysis of mixing effects showed that 10 of the 12 combinations gained positive MErelml mean ranging from 0.25 to 17.37%. This shows that their mean yield was higher by 0.25% to 17.37% than the yield mean of their single component varieties in different environments. VarMix ABCE achieved the highest MErelml value of 175.86% in Carmen, Bohol with a 17.37% mean. ABCE also had positive MErelml (1.44% to 19.76%) in Agusan del Norte; Aurora; Nabonton, Ligao, City Albay; Batac City, Ilocos Norte; Iloilo; Nueva Ecija; PhilRice Batac, and PhilRice Bicol. Further, ABCE had the highest positive MEmaxml value of 100.79% (found in Bohol), indicating that its yield was 100.79% higher than the maximum yield of its corresponding variety. Batac City and Iloilo likewise had positive MEmaxml of 1.40% and 0.90%. VarMix combinations BDE, AFE, ABCEF, and ABCDEF reached higher D(x)ml with the same mean values of 0.7 across the 12 locations. The highest D(x)ml of 1.9 was found in BDE and BCD. Based on the static measure of all genotype stability, BDE and single variety NSIC Rc 298 attained small �!i values of 2.0, where the lower the value of variability the more stable they were. In the analysis on responsiveness to environmental productivity, ADCEF was the most responsive and the largest stability (bi) value of 1.2 followed by ACDE, ABC and AFE with 1.1; bi >1 means they have higher responses to a given environment. VarMix combinations that showed yield increase through the mixing effects analysis in actual field conditions will facilitate the selection of elite VarMix for future deployment in areas with similar environment. Results from this study highlighted the potential of VarMix as a stop-gap approach for increasing yield in rice production areas with limited source of water and unpredictable occurrences of pests and diseases.

Sahelian smallholders’ varietal mixtures reconcile yield and agrobiodiversity conservation

In the current setting, marked by the major challenges of growing food demand and climate change impacts, the ability of sub-Saharan agriculture to meet population needs depends on the resilience and adaptation capacity of this system. Using agrobiodiversity to promote agricultural sustainability is a strategy that has garnered much attention lately. Research suggests that mixing species or varieties within crop fields could increase the yield and/or stability. This mixing is also geared towards the conservation of crop diversity while ensuring that the various associated products and services will be available at the farm level.Few recent research studies have highlighted the benefits of varietal mixtures for Africa. This lack of research is a concern, given that this continent is considered to be highly vulnerable to climate change. This study was carried out to test whether plots with varietal mixtures would outperform monovarietal plots in terms of yield and pathogen regulation under smallholder farming conditions in Senegal. Together with farmers, we conducted 30 experiments in which mixtures of early- and late-flowering pearl millet landraces were grown in these farmers’ fields, while monitoring their low input management. We noted a significant positive effect of varietal mixtures on grain yield (mean gain of 63 ± 31.5 kg ha−1 for mixture plots, p = 0.046) with a relative yield total (RYT) averaging 1.87 ± 0.94. Both early- and late-flowering landraces benefited from mixtures, with a greater impact on late-flowering landraces. Higher fertility in terms of the seed number, percentage of fertile tillers and number of panicles per tiller, was documented in mixture plots. We did not find a significant effect of mixture on fodder, striga or weed infestation.In water and nutrient resource limiting conditions, such as in Sahelian agroecosystems, growing mixtures of early- and late-flowering landraces appeared to be an efficient way to increase productivity while ensuring agrobiodiversity conservation. Perhaps even more importantly, mixtures allowed farmers to harvest multiple products with different uses in an agrosocioecosystem context with constantly increasing land pressure.

Diversity matters in wheat mixtures: A genomic survey of the impact of genetic diversity on the performance of 12 way durum wheat mixtures grown in two contrasted and controlled environments.

In ecology, an increase in genetic diversity within a community in natural ecosystems increases its productivity, while in evolutionary biology, kinship selection predicts that relatedness on social traits improves fitness. Varietal mixtures, where different genotypes are grown together, show contrasting results, especially for grain yield where both positive and negative effects of mixtures have been reported. To understand the effect of diversity on field performance, we grew 96 independent mixtures each composed with 12 durum wheat (Triticum turgidum ssp. durum Thell.) inbred lines, under two contrasting environmental conditions for water availability. Using dense genotyping, we imputed allelic frequencies and a genetic diversity index on more than 96000 loci for each mixture. We then analyzed the effect of genetic diversity on agronomic performance using a genome-wide approach. We explored the stress gradient hypothesis, which proposes that the greater the unfavourable conditions, the more beneficial the effect of diversity on mixture performance. We found that diversity on average had a negative effect on yield and its components while it was beneficial on grain weight. There was little support for the stress gradient theory. We discuss how to use genomic data to improve the assembly of varietal mixtures.

Exploring Varietal Mixtures as a Strategy for Sustainable Management of Insect Pests Associated with Cabbage [Brassica oleraceaVAR. capitata L. (Brassicaceae)

Cabbage is a highly nutritious vegetable, yet faced with pest challenges. At present, synthetic pesticides are the major control measure and this has some side effects such as; resistance by pest, adverse effect on non-target organisms and hazardous effects on environment. All these problems bring the sustainability of ecosystem to danger. Exploring varietal mixture of cabbage as an alternative for sustainable pest management of cabbage was investigated during the rainy (April, – August 2020) and dry (November, 2020 – March, 2021) seasons. Treatments consisted of Purple-ball, GloriaF1, Oxylus (sole each and mixture) in ratio 1:1 respectively, all raised in nursery beds and transplanted to treatment plots, given a total of 7 treatments, all laid out in a Randomized Complete Block Design (RCBD) with three replicates each. The insect associated with the crop were sampled using sweep net, pitfall traps and the mechanical hand-picking methods. The phytochemical components of each variety were also carried out. Results showed that cabbage which was mixed with purple-ball variety showed reduced attack by insects as compared with Gloria and Oxylus planted sole. This could be attributed to the higher value of cardiac glycoside, tannins, steroids and anthraquinone in Purple-ball variety than other varieties. These compounds are responsible for plant defence which may have caused the low insect population in Purple-ball variety. The yields from Purple-ball variety plots in both seasons were however significantly lower compared with other varieties in both seasons. Notwithstanding, the yield from the mixture of purple-ball with other varieties was not significantly different from others. Therefore, the inclusion of Purple-ball variety in GloriaF1 and Oxylus production is recommended as this may serve as a natural defence against insect pests. Also, the use of this cropping system is not only effective but inexpensive and safe for human health and the environment relative to synthetic insecticides.

Evaluation of yield and agronomic performance of leafed and semi‐leafless pea blends

AbstractField pea (Pisum sativum L.) has two distinct leaf morphologies, leafed (L) and semi‐leafless (SL). Grown together, SL and L pea blends have better weed control and higher crop yield than sole crops of either leaf type. Previous studies have only investigated mixing leaf types from two distinct varieties, and therefore the blend could be affected by traits specific to each pea variety rather than the difference in leaf type. To determine if yield and agronomic improvement of pea leaf blends are due solely to leaf type, this study (a) compared leaf blends of near‐isogenic lines with the same varieties grown in monoculture, and (b) determined whether intercepted solar radiation, disease‐resistance, lodging performance, biomass, and yield were improved by growing a varietal mixture. Five field experiments tested all possible pairings of four near‐isogenic L and SL lines in a single ratio (75:25, SL/L), compared with monocultures (100% SL or 100% L). The results found that the leaf‐type blends had 11% less lodging than the L monoculture and had an 8.5% greater seed yield than the L monoculture in one variety. The near‐isogenic blends and non‐isogenic blends did not differ significantly for foliar disease, lodging, biomass, yield, and yield stability. Consequently, the exhaustive comparison of near‐isogenic or non‐isogenic blends grown under multiple environments indicates that SL and L pea blends have nonsignificant yield and agronomic advantages compared with SL monocultures.

Combining computer vision and deep learning to classify varieties of Prunus dulcis for the nursery plant industry

AbstractVarietal control to avoid unwanted varietal mixtures is an important objective for the nursery plant industry. In this study, we have developed and analyzed the capabilities of a computer vision system based on deep learning for the control of plant varieties in the nursery plant industry and for evaluating its capabilities. For this purpose, three datasets of nursery plant images were compared. The datasets came from two varieties of almond trees (Prunus dulcis) named Soleta and Pentacebas. Each dataset contained images with three different scales: whole plant, leaf, and venation. The Gradient‐weighted Class Activation Mapping (Grad‐CAM) technique was used to unveil the most important features to discriminate between both varieties. The three datasets provided classification accuracies above 97% in the test set, being the leaf dataset, with a 98.8% accuracy, the one providing the best results. Concerning the most important features of the plants, the Grad‐CAM showed that they are located in the center of the leaf, that is, the venation. In conclusion, we have shown that computer vision is a promising technique for the control of plant varietal mixtures.

​Effects of Genotypic Diversity on Insect-pests of Soybean

Background: Intercropping and mixed cropping based on two or more different crops have been widely used in Insect Pest Management to manage the population density of insect pests in various crops like maize with soybean, sorghum with soybean and sunflower with soybean. Genotypic diversity is the mixture or combination of various varieties/lines/genotypes of a crop. It decreases the insect-pests population by unfitness of crop to them due to intraspecific diversity such as mixture of susceptible and resistant varieties. Also, it increases the natural enemy population more due to longer period of flowering, availability of wide diverse food, more movement of herbivores etc. This concept has also been used successfully to manage insect-pests in maize, wheat and potato. In India, this connect is used in very small scale in crop. The objective of this study was to determine effects of genotypic diversity by comparing the population densities of major insect pests between monoculture of single variety and mixture of varieties. Methods: To test the effects of genotypic diversity on soybean insect-pest and their natural enemy population an experiment was laid in kharif 2018 and 2019 at the ICAR-Indian Institute of Soybean Research, Indore. All recommended agronomic package of practices were followed for raising of crop. Randomized block design with three replication having plot size of 9 rows of 5 meter row length was used. Totally 20 treatments were chosen for this experiment and out of 20 four treatments namely, T1, T6, T11 and T16 were the treatments of four varietal mixture treatments of almost similar maturity duration and agronomic traits and rest of treatments were of sole varietal treatments. Observations were made on insect-pests from 10 selected plants in each plot on three leaves selected at top, middle and lower portion of plant. Result: Effects of genotypic diversity in soybean revealed that for whitefly management T11 (NRC-86, JS-335, JS-2098 and RKS-45) was found most effective treatment. In case of mite, thrips and treehoppers management T1 (JS-9560, JS-20-34, MAUS-47 and MAUS-1460) was found most effective treatment. For leafhopper and mealy bug T6 (JS-9305, JS-2029, RVS-2001-4 and Dsb-28-3) was found most effective treatment. While for spittlebug T16 (NRC-37, JS-9752, RSC-1046 and RKS-113) was found most effective treatment. So, genotypic diverse treatments were found more effective than their respective sole varietal treatments.

Plant neighbour-modulated susceptibility to pathogens in intraspecific mixtures.

As part of a trend towards diversifying cultivated areas, varietal mixtures are subject to renewed interest as a means to manage diseases. Besides the epidemiological effects of varietal mixtures on pathogen propagation, little is known about the effect of intraspecific plant-plant interactions and their impact on responses to disease. In this study, genotypes of rice (Oryza sativa) or durum wheat (Triticum turgidum) were grown with different conspecific neighbours and manually inoculated under conditions preventing pathogen propagation. Disease susceptibility was measured together with the expression of basal immunity genes as part of the response to intra-specific neighbours. The results showed that in many cases for both rice and wheat susceptibility to pathogens and immunity was modified by the presence of intraspecific neighbours. This phenomenon, which we term 'neighbour-modulated susceptibility' (NMS), could be caused by the production of below-ground signals and does not require the neighbours to be infected. Our results suggest that the mechanisms responsible for reducing disease in varietal mixtures in the field need to be re-examined.

Landscape-dependent effects of varietal mixtures on insect pest control and implications for farmer profits.

Intraspecific plant diversity can significantly impact insect herbivore populations in natural systems. Yet, its role as an insect pest control strategy in agriculture has received less attention, and little is known about which crop traits are important to herbivores in different landscape contexts. Moreover, empirical economic analyses on the cost‐effectiveness of varietal mixtures are lacking. We used varietal mixtures of Brassica oleracea crops on working farms to examine how two metrics of intraspecific crop diversity, varietal richness and number of plant colors (color richness), affect crop damage and the incidence and abundance of two insect pest species: Pieris rapae and Phyllotreta spp. We evaluated the context‐dependency of varietal mixtures by sampling early‐ and late‐season plantings of B. oleracea crops in farms across a gradient of landscape composition. We developed crop budgets and used a net present value analysis to assess the impact of varietal mixtures on input and labor costs, crop revenues, and profit. We found context‐dependent effects of varietal mixtures on both pests. In early‐season plantings, color richness did not affect Phyllotreta spp. populations. However, increasing varietal richness reduced Phyllotreta spp. incidence in simple landscapes dominated by cropland, but this trend was reversed in complex landscapes dominated by natural habitats. In late‐season plantings, color richness reduced the incidence and abundance of P. rapae larvae, but only in complex landscapes where their populations were highest. Varietal richness had the same effect on P. rapae larvae as color richness. Unexpectedly, we consistently found lower pest pressure and reduced crop damage in simple landscapes. Although varietal mixtures did not affect crop damage, increasing color richness corresponded with increased profits, due to increased revenue and a marginal reduction in labor and input costs. We demonstrate varietal mixtures can significantly impact pest populations, and this effect can be mediated by intraspecific variation in crop color. However, the strength and direction of these effects vary by season, landscape composition, and pest species. The association between varietal color richness and profitability indicates farmers could design mixtures to enhance economic returns. We recommend additional research on the benefits of intraspecific trait variation for farmers.

CHANGE IN VARIETAL PURITY OF FLAXSEEDS WHEN THEY ARE CLOGGED WITH SEEDS OF INTER-GARLIC FORM OF FLAX IN THE PROCESS OF THEIR REPRODUCTION IN PRIMARY SEED FARMING NURSERIES

The most common reason for the appearance of varietal impurities in flax crops is the non-compliance with the main provisions of on-farm control when working with two or more varieties of flax on the farm or during variety changer. Field testing does not always give a correct assessment of the condition of crops by varietal purity. Due to the unevenness of the crops in the field, the morphological assessment of individual plants with a handful analysis does not allow to reliably determine the percentage of biological impurities of the baggage type. The purpose of the research was to study the dynamics ofpropagation of varietal pollutant-type admixture, which has a yellow color of seeds, in the seeds of flax littered by it at a 3-year reseeding. Clarify the index of varietal purity of flax seed OS category in GOST R 52325-2005. Studies were conducted in 2015-2017 in the field of the Experimental Field of the Institute of Flax (Torzhoksky District, Tver Region). The object of the study was plants and seeds of flax Antey variety (control). The use of varietal mixtures with marker traits made it possible to accurately determine its content in the crop during the successive propagation of seeds in primary seedfarming nurseries. It has been established that over three years of reproduction, the amount of varietal impurity in the crop according to the experimental variants with the impurity content from 0.2 to 0.7% increased by 0.2 ... 0.3%; with a clogging of 1.0%, there was a more significant increase in its yield by 0.4% in 2015 and by 1.6% in 2017. Under conditions of excessive moisture in 2016, the content of varietal admixture seeds decreased by 0.1% compared to the previous year.

Multifaceted functional diversity for multifaceted crop yield: Towards ecological assembly rules for varietal mixtures

Abstract Ecological theories suggest that higher plant genetic diversity can increase productivity in natural ecosystems. So far, varietal mixtures, that is, the cultivation of different genotypes within a field, have shown contrasting results, notably for grain yield where both positive and negative mixing effects have been reported. Such discrepancy between ecological theories and agronomical applications calls for a better understanding of plant–plant interactions in crops. Using durum wheat Triticum turgidum ssp. durum as a model species, we investigated the effect of functional trait composition on productivity and grain quality of varietal mixtures by growing 179 highly diverse genotypes in pure stands and 197 two‐way mixtures in field conditions. We quantified the agronomic performance of the mixtures relative to their components grown in pure stands on two variables related to productivity, vegetative biomass yield and grain yield, and one variable related to grain quality, grain protein content. We then analysed the relationship between the relative performance of the mixtures and their functional composition that we characterized with trait means and trait differences on 19 above‐ and below‐ground traits. We found that biomass and grain yield increased by 4% overall in mixtures relative to single varieties, but that mixing effects were non‐significant for grain protein content. The combined effects of trait means and trait differences explained 12%, 17% and 22% of the variability of relative grain yield, biomass yield and grain protein content, respectively, with different traits affecting productivity and grain quality. Clustering varieties into functional groups allowed us to identify the most beneficial associations for multifaceted agronomic performance. Synthesis and applications. Functional traits explained a significant part of the relative agronomic performance of mixtures compared to monocultures (12%–22%, depending on the yield component). They can thus serve as a basis to identify groups of varieties whose combinations are expected to generate positive mixing effects, especially for productivity, and without compromising grain quality. Selection could then target convergence between groups for some traits and divergence between groups for other traits using empirically derived relationships between functional traits and agronomic performance as a guideline.

Crop Varietal Mixtures as a Strategy to Support Insect Pest Control, Yield, Economic, and Nutritional Services

Most on-farm diversification strategies to enhance ecosystem services, such as insect pest control and yield, have focused on expanding crop species diversity. While polycultures often provide valuable services, logistical constraints with planting and harvesting can hamper implementation on large scales. An alternative diversification strategy is to increase within-field intraspecific crop diversity through the use of crop varietal mixtures. Here, we evaluate an interdisciplinary body of research to determine the potential for crop varietal mixtures to support food security by providing ecological, economic, and nutritional services. Previous literature has synthesized the link between varietal mixtures and yield and insect pest suppression services. We expand on prior analyses by considering hypotheses generated from species-level research and assessing whether they also provide a useful framework for predicting how varietal mixtures affect crop productivity and insect pest suppression. In addition, we evaluate the potential for varietal mixtures to increase farm resilience and growers’ profits. While there is a growing effort to quantify the economic value of ecosystem services provided by agrobiodiversity in terms of enhanced yield or revenue, much less attention has been given to quantifying the production costs associated with diversification schemes. Consequently, we know little about the effect of diversification practices on farm profitability, the metric of ultimate importance to farmers. We address this issue by evaluating the ability of varietal mixtures to reduce production costs associated with other types of agrobiodiversity and outline areas for future research to better understand the profit implications of varietal mixtures. Further, we review evidence that varieties of some crop species differ in phytochemical content—a functional trait important for insect pest suppression and human dietary diversity—suggesting that varietal mixtures could be designed to simultaneously support insect pest control and human nutrition services. Given that little research has explicitly addressed the capacity for varietal mixtures to support human nutrition, we outline predictions for where we would expect to see the greatest nutritional impact of mixtures, providing a foundation for future human nutrition research. Taken together, our review suggests that varietal mixtures are a promising and logistically feasible strategy that could simultaneously support multiple services.

Role of Intra-Specific Varietal Mixture in Pollination Services: A Case Study in Buckwheat (Fagopyrum esculentum Moench)

Buckwheat is one of the crops on which pollination services from honeybees and other insect pollinators are necessary for obtaining quality and higher grain yield. Increasing plant biodiversity is an important strategy to attract and restore pollinators in an agro-ecosystem. Among many ways to increase plant biodiversity, the present study aimed to identify whether the increasing intra-specific crop diversity enhances pollinator diversity in buckwheat (Fagopyrum esculentum Moench). The field experiment was conducted at research field of Hill Crop Research Program, Kabre, Dolakha district, Nepal at an altitude of 1750 m asl during 2016. Thirteen treatments, each representing either a single or combination of two or three buckwheat genotypes were laid out in randomized complete block design (RCBD) with two replications. Pollination diversity or richness as well as their foraging behavior in the buckwheat flowers and associated yield parameters were measured for each treatment. Plots with higher intra-specific varietal mixture were found to attract more pollinators and had higher yield than plots with two or single genotypes. Pollinator visitation was higher during morning hour of the day (9 am to 10 am), which was followed by mid-day (12 noon to 1 pm) and the least visitation was observed during late afternoon (3 pm to 4 pm). The benefit of increasing intra-specific crop diversity on pollination services is not optimized and practiced under current farming practices. Hence, multi-location and multi-season studies are recommended to strengthen the current findings for future endeavors.

Development of a methodology to analyze leaves from Prunus dulcis varieties using near infrared spectroscopy

Near-infrared spectroscopy (NIRS) can be a faster and more economical alternative to traditional methods for screening varietal mixtures of nursery plants during the propagation process to ensure varietal purity and to avoid errors in the dispatch batches. The global objective of this work was to develop and optimize a NIR spectral collection method for construction of robust multivariate discrimination models. Three different varieties of Prunus dulcis (Avijor, Guara, and Pentacebas) of agricultural interest were used for this study. Sources of variation were investigated, including the position of the leaves on the trees, differences among trees of the same variety, and differences at the varietal level. Three types of processed samples were investigated. Fresh leaves, dried leaves, and dried leaves in powder form were included in each analysis. A study of spectral pre-treatment methods was also performed, and multivariate methods were applied to analyze the influence of different factors on classification. These included principal component analysis (PCA), partial least squares discriminant analysis (PLS-DA), and ANOVA simultaneous component analysis (ASCA). The results indicated that variety was the most important factor for classification. The spectral pre-treatment that provided the best results was a combination of standard normal variate (SNV), Savitzky-Golay first derivative, and mean-centering methods. With regard to the type of processed sample, the highest percentages of correct classifications were obtained with fresh and dried powdered leaves at both the training set and test set validation levels. This study represents the first step towards the consolidation of NIRS as a method to identify Prunus dulcis varieties.

QUANTITATIVE DETERMINATION OF PHENOL CARBOXYLIC ACIDS IN POMEGRANATE FRUIT PULP BY THE HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY WITH ULTRAVIOLET DETECTION

Objective: Pomegranate (Punica granatum L.) is a broadly used plant possessing a wide range of medicinal properties. In this research, we have mainly focused on the investigation of phenolic compounds of pomegranate fruit pulp (PFP).Methods: Fresh fruits of “Çəhrayı Gülöyşə,” “Kizil-anor,” and pomegranate varietal mixture were used as samples. High-performance liquid chromatography-ultraviolet (HPLC-UV) analysis of phenol carboxylic acids was performed with metal column Kromasil® C18 (4.6×250 mm, particle size 5 μm) and the acetonitrile-water-concentrated acid phosphoric system (400:600:5) under isocratic elution conditions (flow rate of 0.5 ml/min). Detection was carried out using a UV detector “GILSTON” UV/Visible model 151 at a wavelength of 280 nm.Results and Discussion: As a result of our research, we proposed chromatographic conditions for the separation of phenolic compounds, the conditions for sample preparation of PFP. Procedure for determination of phenolic carboxylic acids total content in terms of gallic acid by HPLC-UV method was developed. According to the obtained data, the content of phenolic carboxylic acids should be at least 0.7%.Conclusion: Procedure for the quantitative determination of gallic acid using the HPLC-UV method was developed. This method which can be used in the standardization of new medicinal plant raw materials - PFP, as well as extract preparations based on it in the future.

QUANTITATIVE DETERMINATION OF PHENOL CARBOXYLIC ACIDS IN POMEGRANATE FRUIT PULP BY THE HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY WITH ULTRAVIOLET DETECTION

Objective: Pomegranate (Punica granatum L.) is a broadly used plant possessing a wide range of medicinal properties. In this research, we have mainly focused on the investigation of phenolic compounds of pomegranate fruit pulp (PFP).Methods: Fresh fruits of “Çəhrayı Gülöyşə,” “Kizil-anor,” and pomegranate varietal mixture were used as samples. High-performance liquid chromatography-ultraviolet (HPLC-UV) analysis of phenol carboxylic acids was performed with metal column Kromasil® C18 (4.6×250 mm, particle size 5 μm) and the acetonitrile-water-concentrated acid phosphoric system (400:600:5) under isocratic elution conditions (flow rate of 0.5 ml/min). Detection was carried out using a UV detector “GILSTON” UV/Visible model 151 at a wavelength of 280 nm.Results and Discussion: As a result of our research, we proposed chromatographic conditions for the separation of phenolic compounds, the conditions for sample preparation of PFP. Procedure for determination of phenolic carboxylic acids total content in terms of gallic acid by HPLC-UV method was developed. According to the obtained data, the content of phenolic carboxylic acids should be at least 0.7%.Conclusion: Procedure for the quantitative determination of gallic acid using the HPLC-UV method was developed. This method which can be used in the standardization of new medicinal plant raw materials - PFP, as well as extract preparations based on it in the future.

Varietal mixtures and multispecies mixtures – strengths and constraints

Varietal mixtures and multispecies mixtures – strengths and constraints