High-yielding Cultivars Research Articles

Selecting traits to improve the yield and water use efficiency of winter wheat under limited water supply

Using high-yielding cultivars is an important measure to maintain grain production, especially in dryland environments. A field study in the 2016/17 and 2017/18 seasons was conducted at Luancheng station in the North China Plain (NCP) to investigate winter wheat cultivars with high-yielding characteristics under water deficit conditions. The experiment contained two parts, with part one involving 10 cultivars of winter wheat grown under I0 (rainfed), I1 (one irrigation) and I2 (two irrigations) treatments and part two involving 32 cultivars grown under I1 treatment. The three irrigation regimes I0, I1, and I2 provided approximately 60 %, 70 % and 80 % of the seasonal potential evapotranspiration, respectively. Yield variations were up to 47 % among the 10 cultivars in the two seasons, and several cultivars could produce continuously higher yields than those of other cultivars under the different treatments. High-yielding cultivars produced higher water productivity than that of other cultivars. No single agronomic or physiological characteristics, except for biomass, could explain the yield differences among cultivars. However, canopy temperature (CT) during the grain filling stage had a continuous negative linear correlation with grain yield under limited water supply conditions in a high-yielding environment. The results indicated that the genetic variation in grain yield might be attributed to the ability to withdraw soil water, especially the deeper soil water, during the grain filling stage, which would result in a cooler canopy. CT as an indicator of high-yielding cultivars was further confirmed among the 32 cultivars under I1 treatment in the 2016/17. A relative adequate water supply during the grain filling stage also prolonged leaf greenness which was beneficial to dry matter production and grain yield. Therefore, the ability to efficiently utilize soil water and maintain dry matter production during the grain filling stage are two important characteristics for maintaining the high yield of winter wheat under water deficit conditions in the NCP.

English

The loss of maize landraces is of major global concern. Landraces provide the genetic building blocks for the development of high yielding pest- and drought-tolerant maize varieties, and their loss reduces the capacity to adapt to changing environmental conditions. The extinction of maize landraces is an incidental effect of the planting decisions of farmers. Although maize landraces are important both as a staple food and the source of traditional specialty foods required in particular cultural events and ceremonies, they are frequently displaced by high-yielding cultivars. The study considers the factors influencing on-farm maize diversity in the Lacandon tropical forest in the Mexican state of Chiapas. Using a censored regression model fitted with cross-sectional household farmer data, the factors behind crop choices was investigated, paying particular attention to the relation between crop diversity, wealth, and income transfers. It was found that maize diversity bears a non-monotonic relation to wealth, but is positively associated with both agricultural subsidies and poverty support. Key words: Crop choice, crop diversity, Lacandon forest, maize diversity, poverty, on-farm conservation, Mexico, censored regression. &nbsp

Discovery of simple sequence repeat (SSR) markers in hazelnut (Corylus avellana L.) by transcriptome sequencing and SSR-based characterization of hazelnut cultivars

ABSTRACT Current cultivation and breeding strategy based on selections from local and wild vegetation does not meet the hazelnut demand. This situation would benefit from the development of high-yielding cultivars with greater tolerance to abiotic and biotic stress conditions. Molecular markers are useful tools to support these breeding efforts. In the current study, EST-SSR markers were developed from RNA-sequencing data obtained from three hazelnut varieties. The transcriptome sequences contained 86,542 unigenes and a total of 25,391 SSRs, most of which (50.9%) were di-nucleotide repeats. A set of 40 primer pairs were randomly selected to validate their usefulness for investigating genetic diversity in 19 C. avellana cultivars and one accession of Corylus colurna. Of the 40, 28 were highly polymorphic with average values of observed heterozygosity, polymorphism information content and number of alleles per locus of 0.45, 0.67 and 6.11, respectively. The principal coordinate and dendrogram analysis separated the C. colurna accession from the C. avellana cultivars, and separated the cultivars for date of leaf bud burst. These new EST-SSRs and others that could be developed from the transcriptome sequences increase the number of markers for cultivar fingerprinting and may be useful for identifying marker-trait associations and further genetic diversity analyses.

Combining Ability of Extra-Early Maize Inbreds Derived from a Cross between Maize and Zea diploperennis and Hybrid Performance under Contrasting Environments

Knowledge of the genetic mechanisms conditioning drought tolerance in maize is crucial to the success of hybrid breeding programs aimed at developing high-yielding cultivars under drought. The objectives of this study were to determine the combining ability of extra-early inbreds, compute the heritability of measured traits, assess the performance of inbreds in hybrid combinations and investigate the associations among traits under drought and optimal conditions. A total of 252 hybrids generated by crossing 63 inbreds to four testers, along with four commercial hybrid checks, were evaluated for 2 years under drought and rainfed conditions. General combining ability (GCA) and specific combining ability (SCA) for the traits were significant. A total of 57.1% and 53.4% of the genotypic sum of squares were attributable to GCA effects for grain yield under managed drought and rainfed conditions, respectively. Hybrids TZdEEI 91 × TZEEI 21 and TZdEEI 55 × TZEEI 13 out-yielded the best checks under drought and optimal conditions by 49.13% and 39.05%, respectively. The most promising hybrids with consistently high grain yield under drought and rainfed conditions, were TZdEEI 54 × TZEEI 13, TZdEEI 91 × TZEEI 21 and TZdEEI 55 × TZEEI 21 and should be further evaluated for possible commercial production in sub-Saharan Africa.

High yielding ability of a large-grain rice cultivar, Akita 63

To increase the yield potential while limiting the environmental impact of N management practices is an important issue in rice cultivation. The large-grain rice cultivar Akita 63 showed higher N-use efficiency for grain production. To elucidate this, we analyzed yield characteristics of Akita 63 in comparison with those of a maternal cultivar, Oochikara with a large grain, a paternal cultivar, Akita 39 with a normal grain, and a Japanese leading cultivar, Akitakomachi. The yields of Akita 63 were 20% higher than those of Oochikara and Akita 39, and 50% higher than those of Akitakomachi for the same N application. Akita 63 showed superior N uptake capacity. Whereas a trade-off between single grain weight and grain number was found for Oochikara, Akita 63 did not show such a relationship. The success in Akita 63 breeding was due to overcoming such a trade-off. Akita 63 had the large-grain alleles of GS3 and qSW5. Thus, an enlargement of grain size can have a great impact on an increase in yield with improved N-use efficiency. However, an enlargement of sink capacity led to source limitation. Thus, both sink and source improvements are essential for a further increase in the yield of today’s high-yielding cultivars.

Cercospora beticola: The intoxicating lifestyle of the leaf spot pathogen of sugar beet.

Cercospora leaf spot, caused by the fungal pathogen Cercospora beticola, is the most destructive foliar disease of sugar beet worldwide. This review discusses C. beticola genetics, genomics, and biology and summarizes our current understanding of the molecular interactions that occur between C. beticola and its sugar beet host. We highlight the known virulence arsenal of C. beticola as well as its ability to overcome currently used disease management strategies. Finally, we discuss future prospects for the study and management of C. beticola infections in the context of newly employed molecular tools to uncover additional information regarding the biology of this pathogen.Taxonomy Cercospora beticola Sacc.; Kingdom Fungi, Phylum Ascomycota, Class Dothideomycetes, Order Capnodiales, Family Mycosphaerellaceae, Genus Cercospora.Host rangeWell‐known pathogen of sugar beet (Beta vulgaris subsp. vulgaris) and most species of the Beta genus. Reported as pathogenic on other members of the Chenopodiaceae (e.g., lamb's quarters, spinach) as well as members of the Acanthaceae (e.g., bear's breeches), Apiaceae (e.g., Apium), Asteraceae (e.g., chrysanthemum, lettuce, safflower), Brassicaceae (e.g., wild mustard), Malvaceae (e.g., Malva), Plumbaginaceae (e.g., Limonium), and Polygonaceae (e.g., broad‐leaved dock) families.Disease symptomsLeaves infected with C. beticola exhibit circular lesions that are coloured tan to grey in the centre and are often delimited by tan‐brown to reddish‐purple rings. As disease progresses, spots can coalesce to form larger necrotic areas, causing severely infected leaves to wither and die. At the centre of these spots are black spore‐bearing structures (pseudostromata). Older leaves often show symptoms first and younger leaves become infected as the disease progresses.ManagementApplication of a mixture of fungicides with different modes of action is currently performed although elevated resistance has been documented in most employed fungicide classes. Breeding for high‐yielding cultivars with improved host resistance is an ongoing effort and prudent cultural practices, such as crop rotation, weed host management, and cultivation to reduce infested residue levels, are widely used to manage disease.Useful website https://www.ncbi.nlm.nih.gov/genome/11237?genome_assembly_id=352037

The effect of short-term vs. long-term soil moisture stress on the physiological response of three cocoa (Theobroma cacao L.) cultivars

Understanding water stress signaling mechanisms and screening for tolerant cocoa cultivars are major challenges when facing prolonged dry and rainy seasons in cocoa-producing areas. While abscisic acid (ABA) and proline are supposed to enhance drought tolerance in cocoa, the role of polyamines remains unclear. The aim of this study was to investigate the biochemical response and phenological adaptation of cocoa (Theobroma cacao) on different soil moisture conditions, with a focus on short-term (20 days) and long-term (89 days) stress conditions, and to compare the performance of three cocoa cultivars. In a split plot design with four blocks, cocoa seedlings of an international high-yielding cultivar (TSH-565) and two locally selected cultivars (IIa-22 and III-06) from the drought-exposed Alto Beni region, Bolivia, were arranged in pots under a roof shelter (cultivar: three levels). The seedlings were exposed to strong (VERY DRY) and moderate (DRY) soil moisture deficits, water logging (WET) and regular irrigation (MOIST) that served as a control (moisture: four levels). We examined the growth performance and the levels of ABA, proline, and polyamines in the leaves. Growth was reduced already at a moderate drought, while severe drought enhanced seedling mortality. Severe drought increased the levels of ABA by 453% and of proline by 935%, inducing a short-term stress response; both compounds were degraded over the long-term period. The polyamine concentration was unrelated to soil moisture. The cocoa cultivars did not differ in their biochemical response to soil moisture stress (proline: p-value = 0.5, ABA: p-value = 0.3), but the local cultivar III-06 showed a stronger height growth increment than the international cultivar TSH-565 (237%, p-value = 0.002) under drought conditions.

The soil organic carbon stabilization potential of old and new wheat cultivars: a <sup>13</sup>CO<sub>2</sub>-labeling study

Abstract. Over the past decades, average global wheat yields have increased by about 250 %, mainly due to the cultivation of high-yielding wheat cultivars. This selection process not only affected aboveground parts of plants, but in some cases also reduced root biomass, with potentially large consequences for the amount of organic carbon (OC) transferred to the soil. To study the effect of wheat breeding for high-yielding cultivars on subsoil OC dynamics, two old and two new wheat cultivars from the Swiss wheat breeding program were grown for one growing season in 1.5 m deep lysimeters and pulse labeled with 13CO2 to quantify the amount of assimilated carbon that was transferred belowground and can potentially be stabilized in the soil. The results show that although the old wheat cultivars with higher root biomass transferred more assimilated carbon belowground compared to more recent cultivars, no significant differences in net rhizodeposition were found between the different cultivars. As a consequence, the long-term effect of wheat cultivar selection on soil organic carbon (SOC) stocks will depend on the amount of root biomass that is stabilized in the soil. Our results suggest that the process of wheat selection for high-yielding cultivars resulted in lower amounts of belowground carbon translocation, with potentially important effects on SOC stocks. Further research is necessary to quantify the long-term importance of this effect.

Evaluation of Foliar Diseases for Soybean Entries in the Pan-African Trials in Malawi and Zambia.

Soybean production has expanded worldwide including countries in sub-Saharan Africa. Several national and international agencies and research groups have partnered to improve overall performance of soybean breeding stocks and have introduced new germplasm from Brazil and the United States with the goal of developing new high-yielding cultivars. Part of this effort has been to test improved soybean lines/cultivars accumulated from private and public sources in multilocational trials in sub-Saharan Africa. These trials are known as the Pan-African Soybean Variety Trials, and the entries come from both private and public breeding programs. The objective of this research was to evaluate entries in the trials that include commercial cultivars or advanced experimental lines for the incidence and severity of foliar diseases. All trials were planted in December 2018 with six located in Zambia and one in Malawi. Plants were evaluated during the reproductive growth stages using a visual pretransformed severity rating scale. Foliar disease ratings were recorded for three bacterial diseases, six fungal diseases, one oomycete, and viruses. The overall occurrence of most of the diseases was high except for soybean rust and target spot, which were only found at two and one location, respectively. However, disease severity was generally low, although there were differences in disease severity ratings among the entries at some of the locations for brown spot, downy mildew, frogeye leaf spot, red leaf blotch, and soybean rust.

Elastic sowing dates with low seeding rate for grain yield maintenance in mechanized large-scale double-cropped rice production

Elastic sowing dates (ESDs) are correlated with rice grain yield. ESD is the easiest factor for farmers to manipulate in mechanized large-scale farming. In this study, field experiments were conducted over a 2-year period to determine the effects of different sowing dates on growth duration, effective accumulated temperature, and yield attributes in two early- and late-season machine-transplanted rice cultivars. In early rice (ER), a delay in the sowing date led to decreased grain yield and shorter growth duration. In late rice (LR), delayed sowing led to significantly lower grain yield and prolonged growth duration. In LR, significantly positive correlations were detected between effective accumulated temperature in the post-heading stage and both filling ratio and yield. Reproductive redundancy increased markedly in LR, by 7.72% over a 5-day interval. We determined that the ESDs for LR were 10 days later than the control, and that of ER was recommend early sowing rather than late sowing. These findings suggest a new strategy to meet the demands of mechanized large-scale rice farming: the development of thermal sensitive high-yield long-duration ER cultivars and high-yield short-duration LR cultivars.

Defoliation alleviates cold-induced oxidative damage in dormant buds of grapevine by up-regulating soluble carbohydrates and decreasing ROS

The number of pre-bloom, bloom and fruit-set source leaves are the most important determinant of tolerance of buds to low temperatures during winter. In this study, we tested whether pre-bloom (LR-PB), bloom (LR-FB) and fruit-set (LR-FS) hand defoliation are effective in interacting the cold hardiness and biochemical parameters in dormant buds (basal-medium and apical buds) of a high-yielding cultivar Karaerik during period of 2-year field study. In the LR-PB contrary to control (C) was found that basal-medium buds showed high-temperature exotherm (HTE) values and low-temperature exotherm (LTE) values at high temperatures than apical buds; therefore, basal-medium buds (1st, 2nd, 3rd, 4th and 5th) had less tolerance to low temperature than apical buds (6th, 7th, 8th, 9th and 10th). Additionally, the contents of the soluble carbohydrates increased in buds apical after the LR-PB treatment, while malondialdehyde (MDA), hydrogen peroxide (H2O2) and superoxide radical (O2·−) were decreased. The results from defoliation indicated that the LTE values are positively correlated with water content, MDA, H2O2 and O2·− and are negatively correlated with soluble carbohydrates content. Particularly, LR-PB treatment played the key role to explain the difference of cold hardiness between basal-medium and apical buds. Therefore, since LR-PB treatment does not have a negative effect on basal bud survival and increases the survival of apical buds in cool climatic regions, it could be used as a powerful technique for grape cultivars with poor basal buds fruitfulness.

Selection of winter wheat varieties most adapted to the conditions of the Aral Sea region

Relevance and methods. The purpose of the research presented in this article is to select the most suitable winter wheat varieties adapted to the conditions of the Aral Sea region. The recommendation for the production of the most adapted and high-yielding cultivars will help to improve the provision of food to the population. Results. In the conditions of the Republic of Karakalpakstan the most plastic, resistant to adverse climatic conditions and, accordingly, high-yielding are both domestic varieties of ASR, Karadarya and the foreign variety Antonina. These varieties also had the best grain characteristics, such as a mass of 1000 seeds, which can ensure their high seed quality.

Genetic variation and diversity for grain iron, zinc, protein and agronomic traits in advanced breeding lines of pearl millet [Pennisetum glaucum (L.) R. Br.] for biofortification breeding

Genetic improvements of iron (Fe) and zinc (Zn) content in pearl millet [Pennisetum glaucum (L.) R. Br.] may reduce the problems of anemia and stunted growth among millet dependent staple food consumers. The availability of variation in diverse-breeding lines is essential to improve grain micronutrients in high-yielding cultivars. This study aimed to determine the extent of variability, heritability and diversity for grain Fe, Zn and protein, along with key agronomic traits, in 281 advanced breeding lines bred at ICRISAT and evaluated across two seasons (environments). A pooled analysis of variance displayed significant variation for all these traits. Highest variability was recorded for Fe (35–116 mg kg−1), Zn (21–80 mg kg−1), and protein (6–18%), and a three-fold variation was observed for panicle length, panicle girth and 1000-grain-weight (TGW). Diversity analysis showed 10 clusters. Cluster-III had maximum lines (25%) and Cluster-V showed the highest mean values for Fe, Zn, protein and TGW. These results highlight the success of breeding program that aimed both the maintenance and creation of genetic variability and diversity. A significant positive correlation among Fe, Zn, protein and TGW indicated the potential for simultaneous improvement. Grain yield had a non-significant association with Fe and Zn, while protein showed a negative correlation. These results suggest that significant variability exists in elite-breeding lines, thus highlighting an opportunity to breed for biofortified varieties without compromising on the grain yield. The lines with high Fe, Zn and protein content can be used as hybrid parents and may also help in further genetic investigations.

Genetic Diversity, Population Structure and Marker-Trait Association for 100-Seed Weight in International Safflower Panel Using SilicoDArT Marker Information.

Safflower is an important oilseed crop mainly grown in the arid and semi-arid regions of the world. The aim of this study was to explore phenotypic and genetic diversity, population structure, and marker-trait association for 100-seed weight in 94 safflower accessions originating from 26 countries using silicoDArT markers. Analysis of variance revealed statistically significant genotypic effects (p < 0.01), while Turkey samples resulted in higher 100-seed weight compared to Pakistan samples. A Constellation plot divided the studied germplasm into two populations on the basis of their 100-seed weight. Various mean genetic diversity parameters including observed number of alleles (1.99), effective number of alleles (1.54), Shannon’s information index (0.48), expected heterozygosity (0.32), and unbiased expected heterozygosity (0.32) for the entire population exhibited sufficient genetic diversity using 12232 silicoDArT markers. Analysis of molecular variance (AMOVA) revealed that most of the variations (91%) in world safflower panel are due to differences within country groups. A model-based structure grouped the 94 safflower accessions into populations A, B, C and an admixture population upon membership coefficient. Neighbor joining analysis grouped the safflower accessions into two populations (A and B). Principal coordinate analysis (PCoA) also clustered the safflower accessions on the basis of geographical origin. Three accessions; Egypt-5, Egypt-2, and India-2 revealed the highest genetic distance and hence might be recommended as candidate parental lines for safflower breeding programs. The mixed linear model i.e., the Q + K model, demonstrated that two DArTseq markers (DArT-45483051 and DArT-15672391) had significant association (p < 0.01) for 100-seed weight. We envisage that identified DArTseq markers associated with 100-seed weight will be helpful to develop high-yielding cultivars of safflower through marker-assisted breeding in the near future.

Identifying Spring Barley Cultivars with Differential Response to Tillage

Cultivars and some cultivar mixtures of spring barley were grown under inversion and non-inversion tillage conditions for three or four years and assessed for disease and yield in order to obtain genotypes that can be used to determine the mechanisms of cultivation adaptation. In general, the higher-yielding cultivars under inversion tillage conditions gave lower yields under non-inversion tillage, whereas low-yielding older cultivars showed relatively smaller reductions in yield under non-inversion tillage. A few cultivars showed preferential yield performance for either inversion or non-inversion tillage and this was irrespective of their overall yield performance. There was no pedigree or breeding programme link between these cultivars and no above-ground gross morphological trait observed was associated with tillage adaptation. Root hairs may contribute to inversion tillage adaptation as a root hair absence mutant was associated with non-inversion adaptation and it is likely that other root-associated traits are responsible also for tillage adaptation. There was no overall cultivar or tillage interaction with rhynchosporium symptoms but a differential tillage interaction may occur in individual years. We have identified clearly contrasting cultivars and tested their across-season robustness with respect to tillage treatment for further detailed mechanistic studies and identification of tillage adaptation traits.

Polar Experiment Station of VIR: the northernmost outpost of potato research

The establishment and progress of potato cultivation in the Kola Peninsula are closely associated with the Polar Experiment Station of the N.I. Vavilov All-Russian Institute of Plant Genetic Resources (VIR). The data are presented on the development of early-ripening and high-yielding potato cultivars based on the source material from the VIR collection: ‘Imandra’, ‘Sestra Imandry’, ‘Murmansky’, ‘Snezhinka No. 3’, ‘Khibinsky ranny’, etc. Prominent breeders and scientists, who worked at different times at the Polar Station, contributed to the release of unique early-ripening potato cultivars: J. H. Eichfeld, M. N. Veselovskaya, I. A. Veselovsky, F. I. Manykov, M. A. Vavilova, N. N. Ivanova, L. A. Dremlyug, A. M. Kozeletskaya, S. A. Anikina, G. D. Melnichuk, etc. Some of the cultivars developed from 1937 to 1968 are still used in large-scale potato production in Murmansk Province. Every year the cultivar and species diversity of potatoes is planted in the fields of the Arctic North. Today, the extensive material from the potato collection makes it possible to study the impact of environmental factors, identify sources of earliness and productivity, and conduct breeding activities aimed at the release of early cultivars.

Apomixis Technology: Separating the Wheat from the Chaff.

Projections indicate that current plant breeding approaches will be unable to incorporate the global crop yields needed to deliver global food security. Apomixis is a disruptive innovation by which a plant produces clonal seeds capturing heterosis and gene combinations of elite phenotypes. Introducing apomixis into hybrid cultivars is a game-changing development in the current plant breeding paradigm that will accelerate the generation of high-yield cultivars. However, apomixis is a developmentally complex and genetically multifaceted trait. The central problem behind current constraints to apomixis breeding is that the genomic configuration and molecular mechanism that initiate apomixis and guide the formation of a clonal seed are still unknown. Today, not a single explanation about the origin of apomixis offer full empirical coverage, and synthesizing apomixis by manipulating individual genes has failed or produced little success. Overall evidence suggests apomixis arise from a still unknown single event molecular mechanism with multigenic effects. Disentangling the genomic basis and complex genetics behind the emergence of apomixis in plants will require the use of novel experimental approaches benefiting from Next Generation Sequencing technologies and targeting not only reproductive genes, but also the epigenetic and genomic configurations associated with reproductive phenotypes in homoploid sexual and apomictic carriers. A comprehensive picture of most regulatory changes guiding apomixis emergence will be central for successfully installing apomixis into the target species by exploiting genetic modification techniques.

Unlocking the genetic potential of chickpea through improved crop management practices in Ethiopia. A review

Chickpea (Cicer arietinum L.) production in Ethiopia is exclusively rainfed. The average national yield remains low comparing to the potentially attainable yield because of the common notion among producers that the crop does not need any nutrient inputs. The newly developed high-yielding cultivars have brought significant yield gains. However, their genetic potentials are still hampered by the traditional crop management practices used and the problematic Vertisol growing conditions. Yields of chickpea grown on Vertisols are limited by poor drainage when sown early and by drought when sown late. This calls for optimization of the balance with minimum tradeoffs in key economic traits. Here, we review research progress on chickpea over the past five decades in Ethiopia, with particular emphasis on crop management practices. The paper gives a comprehensive overview of research findings and information generated on the Vertisol cropping systems, where chickpea is the principal rotational crop under cereal-legume cultivation entailing substantial role in cropping system intensification. It has been noted that the productivity of Vertisol-grown chickpea is largely constrained more by lack of the use of best bet crop management practices than the genetics of a given cultivar. For instance, raised-bed method as compared to the conventional flatbed increased grain and biomass yields by about 74% and 58%, respectively. The current average farm yield of chickpea in Ethiopia is about 55% of the yield potential of the crop, suggesting that farmers can still have rooms to substantially increase yield using improved practices. Based on the cumulative evidences, it can be concluded that the yield potentials of genetically elite cultivars may not be realized without synergistic combination of improved management practices and adequate nutrient use. We, therefore, recommend the integrated use of improved crop management strategies, while the soil physical properties still deserve utmost research attention.

Characterizing Lentil Germplasm for Zinc Biofortification and High Grain Output

Micronutrient malnutrition particularly of zinc (Zn) attributes a worse situation mainly in South Asia in addition to the food security. Pulses contribute significantly towards providing calories to the masses in developing countries being the cheap source of protein. Zinc biofortification of pulses mainly of lentil can be a good strategy aimed at both increased profit as well as can combat Zn deficiency in humans. A field experiment was conducted to classify the lentil genotypes based on their higher grain output and grain Zn concentration. The 16 lentil genotypes were cultivated with the following Zn levels: 0, 6 and 9 mg kg−1 and recommended dose of primary nutrients (nitrogen (N), phosphorus (P) and potassium (K)) were applied with three replicates until maturity. Results revealed that application of Zn increased the plant growth, grain production and grain Zn concentration significantly. Zinc application at higher rates i.e. 9 mg kg−1 resulted in higher grain output and concentration of Zn in grain than lower application rate and control. The genotype Mansehra-89 was excellent in terms of high grain output and high Zn contents in their grains. The lentil genotypes, Mansehra-89, Punjab Masoor-2009, Masoor-2002 and Masoor-2006, were classified as high grain yield cultivars, and Line-10502, Mansehra-89, Line-11504 and Markaz-09 were categorized as Zn efficient/responsive genotypes. From the results, it was concluded that the lentil genotypes respond differently upon Zn fertilization and thus improved the crop yield and Zn enrichment of lentil grains. However, keeping in view the desired level of bioavailable Zn, further experimentation is required for general recommendations for right source and application methods. Moreover, these categorizations are helpful in future breeding ventures and to recommend the efficient cultivars aiming at increased Zn contents in grains.

Cultivar-specific nutritional status of potato (Solanum tuberosum L.) crops.

Gradients in the elemental composition of a potato leaf tissue (i.e. its ionome) can be linked to crop potential. Because the ionome is a function of genetics and environmental conditions, practitioners aim at fine-tuning fertilization to obtain an optimal ionome based on the needs of potato cultivars. Our objective was to assess the validity of cultivar grouping and predict potato tuber yields using foliar ionomes. The dataset comprised 3382 observations in Québec (Canada) from 1970 to 2017. The first mature leaves from top were sampled at the beginning of flowering for total N, P, K, Ca, and Mg analysis. We preprocessed nutrient concentrations (ionomes) by centering each nutrient to the geometric mean of all nutrients and to a filling value, a transformation known as row-centered log ratios (clr). A density-based clustering algorithm (dbscan) on these preprocessed ionomes failed to delineate groups of high-yield cultivars. We also used the preprocessed ionomes to assess their effects on tuber yield classes (high- and low-yields) on a cultivar basis using k-nearest neighbors, random forest and support vector machines classification algorithms. Our machine learning models returned an average accuracy of 70%, a fair diagnostic potential to detect in-season nutrient imbalance of potato cultivars using clr variables considering potential confounding factors. Optimal ionomic regions of new cultivars could be assigned to the one of the closest documented cultivar.