Exploring the Bush yam (Dioscorea praehensilis Benth) as a Source of Agronomic and Quality Trait Genes in White Guinea yam (Dioscorea rotundata Poir) Breeding

Yam (Dioscorea spp.) is an important food security crop in the tropics and subtropics. However, it is characterized by a narrow genetic base within cultivated and breeding lines for tuber yield, disease resistance, and postharvest traits, which hinders the yam breeding progress. Identification of new sources of desirable genes for these traits from primary and secondary gene pools is essential for this crop improvement. This study aimed at identifying potential sources of genes for yield and quality traits in a panel of 162 accessions of D. praehensilis, a semi-domesticated yam species, for improving the major yam species, D. rotundata. Significant differences were observed for assessed traits (p < 0.05), with D. praehensilis genotypes out-performing the best D. rotundata landraces for tuber yield (23.47 t ha−1), yam mosaic virus (YMV) resistance (AUDPC = 147.45), plant vigour (2.43) and tuber size (2.73). The study revealed significant genotypic (GCV) and phenotypic (PCV) coefficients of variance for tuber yield, YMV severity score, and tuber flesh oxidation. We had also a medium-to-high broad-sense heritability (H2b) for most of the traits except for the dry matter content and tuber flesh oxidation. This study identified some promising D. praehensilis genotypes for traits such as high yield potential (WNDpr76, CDpr28, CDPr7, EDpr14, and WNDpr63), resistance to YMV (WNDpr76, CDpr7, EDpr14, CDpr28, and EDpr13), high dry matter content (WNDpr76, CDpr28, and WNDpr24), low tuber flesh oxidation (WNDpr76, CDpr5, WNDpr31, CDpr40, and WNDpr94) and high number of tubers per plant (WNDpr76, CDpr7, CDpr68, CDpr29, and CDpr58). These genotypes could, therefore, be employed in breeding programmes to improve the white Guinea yam by broadening its genetic base.

Droplet evaporation patterns of wheat seed leakages differ following treatments with arsenic at ultra-high dilution level

Introduction “Agro-homeopathy” plays an important role in sustainable agriculture providing cost-saving and residue-free plant treatments for the improvement of yield and the management of diseases and pests [1]. However, one of the main difficulties in “agro-homeopathy” is the exact choice of the right remedy and dilution, which requires the performance of many time-consuming trials. The droplet evaporation method could constitute a screening method for evaluating the efficacy of extremely low doses and high dilutions on plants. Droplet patterns prepared out of wheat seed leakages show differences in their complexity in relation to the seed vigour [2]. Here we show that this structure-forming capacity of seed leakages prepared in water or in ultra-high diluted (UHD) solutions may give a reliable picture of the treatment’s stimulating or inhibiting influence on plant vitality. Materials and Methods Part of the seeds was stressed with 0.1% As2O3 (As) aqueous solution [3]. The droplet patterns were prepared out of four samples: non-stressed (ns) seeds in water, ns-seeds in As 45x, stressed (s) seeds in water, s-seeds in As 45x. The experiment was performed in a 3 day repetition, 3 replicates per day, and 5 droplets per each replicate. The resulting patterns were evaluated by means of the ImageJ software [4] for their local connected fractal dimension (LCFD) values. The plant vigour of the four samples was evaluated by means of in vitro wheat growth [5, 6]. Results The mean LCFD of patterns deriving from s-seeds was significantly lower (1.4) vs. ns-seeds (1.7). Moreover, for both ns- and s-seeds, the LCFD was significantly higher with treatment As 45x vs. water (1.8 vs. 1.7 for ns-seeds, and 1.5 vs. 1.2 for s-seeds). The results of the growth test showed a significant vigour decrease caused by As stress (shoot length 19.7mm) vs. ns-seeds (22.4mm); a significant stimulating effect following As 45x treatment was observed for both s-seeds (25.1mm) and ns-seeds (31.4). Discussion The droplet patterns seem to be a sensitive tool for visualizing the effectiveness of UHD on seeds. The experiment showed that the pattern complexity increased with the application of the treatment for both ns- and s-seeds. The growth test provided a further verification of these results. Conclusions Further confirmations are required, but even as it is now the droplet evaporation method may be considered a promising tool for “agro-homeopathic” screening tests. Authors declare that there is no conflict of interest and that this study received no funding. References Betti L, Trebbi G, Majewsky V, Scherr C, Shah-Rossi D, Jaeger T, Baumgartner S. Use of homeopathic preparations in phytopathological models and in field trials: a critical review. Homeopathy 2009; 98: 244-266. Kokornaczyk MO, Dinelli G, Marotti I, Benedettelli S, Nani D, Betti L. Self-organized crystallization patterns from evaporating droplets of Common wheat grain leakages as a potential tool for quality analysis. TheScientificWorldJ. 2011; 11: 1712-1725. Brizzi M, Elia V, Trebbi G, Nani D, Peruzzi M, Betti L. The efficacy of ultra molecular aqueous dilutions on a wheat germination model as a function of heat and aging-time. e-CAM 2011; Article ID 696298: 11p. doi: 10.1093/ecam/nep217. Collins TJ. ImmageJ for microscopy. BioTechniques. 2007; 43: 25-30. Betti L, Brizzi M, Nani D, Peruzzi M. Effect of high dilutions of Arsenicum album on wheat seedlings from seed poisoned with the same substance. Br. Homeopath. J. 1997; 86: 86-89. Brizzi M, Lazzarato L, Nani D, Borghini F, Peruzzi M, Betti L. A biostatistical insight into the As2O3 high dilution effects on the rate and variability of wheat seedling growth. Forsch. Komplementmed. 2005; 12: 277-283.

Comparing the effects of crude and refined Mammea americana (Mamey apple) leaf extracts on Doralis symphyti (aphids) on ochro (Hibiscus esculentus) plants

The aphid, Doralis symphyti (Homoptera: Aphididae), a harmful pest of many crops, causes direct damage by consuming all plant parts, reducing plant vigour, and indirect damage by honeydew secretion and transmission of several viruses. Due to the problem of pesticide resistance, alternative techniques for chemical control, such as the use of natural insecticides with minimal effects on the environment and natural enemies also coincide with organic agriculture have been the objective of this research. The effects of Mammea (Mammey americana) leaf extracts on the mortality of aphids were evaluated. The mammey extracts (Crude and refined) were tested in the laboratory (bioassays) at 100%, 90%, 80%, 70% and 60% dilution. The 80% was determined to be the most efficient dilution. The refined extract resulted in 100% mortality at 84 hours while the dry leaf and green leaf extracts gave 100% mortality in 96 hours. In the field, the refined extract resulted in 65% mortality, dry leaf crude extract obtained in 43% mortality and the green leaf crude extract gave 25% mortality. The mamey leaf extracts were efficient against the aphid in the laboratory since 100% mortality was obtained for all treatments. The field study found that the green leaf extract obtained 29% mortality, dry leaf extract achieved 47% mortality and the refined extract attained 63% mortality of aphids.

The response of alfalfa genotypes to different concentrations of mobile aluminium

The morphological traits of alfalfa under acid soil conditions with different mobile aluminium (Al) concentrations were investigated. The study site was Vėžaičiai Branch of the Lithuanian Research Centre for Agriculture and Forestry, 55°70 N, 21°49 E. The experiment featuring the 30 most Al-tolerant alfalfa accessions (populations and cultivars), determined from laboratory trials was established on a Bathygleyic Dystric Retisol in 2018. In 2019 and 2020, the biological and morphological traits were evaluated: plant regrowth, plant height before flowering, wintering, leafiness, stem thickness, plant vigour, stem density, seed yield and resistance to spring black stem leaf spot. The resistance of alfalfa to mobile Al toxicity was determined using a filter-based screening method of selection cycles C1 and C2. The accessions grown in the soil with mobile Al (20.6–23.4 mg/kg) showed better tolerance to Al toxicity in the cycle C2. The hypocotyl tolerance index of these accessions was better at 8, 16, 32 and 64 mm AlCl3 concentrations in the cycle C2. The correlation analysis showed strong significant positive and negative relationships between the morphological traits. A cluster analysis showed that the accessions, grown in the soil with mobile Al (20.6–23.4 mg/kg) were the most resistant to Al toxicity in the cycle C2. These accessions produced a better seed yield and demonstrated lower values of morphological traits compared to cluster 2. Also, these accessions are considered as tolerant to mobile Al toxicity and might be used as donors in breeding for Al toxicity tolerance.

Performance Evaluation of Exotic and Local Landraces of Tomatoes for the Mid-Hill Conditions of Nepal

The productivity of tomato in Nepal is very low due to lack of high yielding, disease and pests resistant varieties. An experiment was carried out to evaluate horticultural traits of 50 genotypes obtained from World Vegetable Centre (WorldVeg), Taiwan and SAARC region, and local collections during March to August 2020 in open field conditions at National Horticulture Research Centre, Khumaltar, Lalitpur. The objectives were to identify promising open-pollinated tomato cultivars for high yield, appropriate fruit size, and disease resistant. The experiment was carried out in a randomized complete block design with three replications. Results showed significant differences in yield and yield attributing characters including virus infection. The highest yield (39.6 mt ha-1) was produced by HRA43 and it was followed by HRA33 (26.4 mt ha-1). Among the WorldVeg OP lines, AVTO1429 produced the highest yield (16.21 mt ha-1) and it was followed by AVTO1717 (12.95 mt ha-1), AVTO0922 (11.83 mt ha-1) and AVTO1219 (11.7 mt ha-1) respectively. Most of the WorldVeg lines performed better than the check variety ‘Pusa Ruby’. Genotype HRA43, Red Local and Sindhupalchock Local were not affected by virus while Yellow Local showed 3.3% infection. Among the WorldVeg lines, AVTO1712 (20%), AVTO1717 (20%) and AVTO1718 (13%) and AVTO1219 (15%) showed less than 20% virus infection in the open field conditions. Cluster analysis using the unweighted paired group method with arithmetic mean showed that cluster-1 was the largest cluster comprised of 40 genotypes followed by cluster-2 and cluster-4. Genotypes from cluster-4 showed the higher fruit yield (25.1 mt ha-1) and resistant to the virus and the highest number of fruits per plot (1978 in 4.5 m2 area). The yield was low in cluster-1 which could be due to the heavy rainfall during the vegetative and reproductive stages. Genotypes Red Local and Sindhupalchock Local could be used in future tomato breeding program due to their resistant to TYLCV, higher potential yield and highest plant vigour in open field conditions at the mid-hill of Nepal. Considering the overall performance, genotype HRA43, HRA33 and AVTO1429 were promising lines with performance for yield and other horticultural traits.

Response of Hops to Algae-Based and Nutrient-Rich Foliar Sprays

Over recent years, some hopyards of northeast Portugal have presented poorly developed plants and reduced productivity. In this study, an attempt was made to improve the homogeneity of hop fields and restore their productivity by using plant biostimulants as foliar sprays. The experimental apparatus included four field trials carried out in four plots of different plant vigour, as evaluated by farmers over previous years (weak, fair, good and very good). The experiments were arranged as a factorial of foliar treatment (two plant biostimulants containing extracts of seaweed algae and an untreated control) and year (2017 and 2018). The plot and the year influenced greatly almost all the measured variables related to tissue nutrient concentration and crop performance. In the control plots, cone dry matter (DM) yield varied from 83.3 to 394.4 g plant−1 from the weak to the very good plots. In 2018, cone DM yield was significantly higher than in 2017. The use of foliar sprays influenced less the elemental composition of plant tissue than the plot or the year. The use of foliar sprays only increased significantly crop yield in the plot of weak plant vigour. The foliar treatments did not increase α- and β-acid concentration in the cones; in the control treatment of the most productive plot, the values were, respectively, 11.2 and 3.9%. Although seaweed extracts tend to help plants cope with several abiotic and biotic stresses, they showed to be effective in mitigating the stress that is affecting these plants, which probably is poor soil drainage caused by the flooding irrigation system, only under conditions of severe stress.

​Influence of Pre-sowing Treatments, Sowing Positions and Age of Stones after Extraction from Fruit on Germination and Vigour of Mango

Background: Mango stones are in general recalcitrant. Moreover, they are available only during April- May months which are the drier parts of the year. So stone germination and plant vigour are very low. Proper seed orientation, age of stones after extraction from fruit and pre-sowing treatments need to be taken into consideration for inducing early germination, boosting growth, enhancing the seedling vigour and reducing the mortality. Methods: The experiment was laid out in factorial completely randomized design with forty two treatment combinations replicated thrice. The treatments were comprised of two sowing positions viz., flat and stalk end up, three age of stones after extraction from fruit, viz., fresh extracted, 10 days and 20 days after extraction and seven pre-sowing treatments viz., 100 ppm GA3, 200 ppm GA3, 1 ppm KNO3, 2 ppm KNO3, cow dung slurry, water, control and their combinations. Result: Stalk end up sowing of freshly extracted stones pre-treated with 200 ppm GA3 for 24 hours recorded better germination and vigour of mango seedlings.

The effect of cane vigour on the kiwifruit (Actinidia chinensis) and kiwiberry (Actinidia arguta) quality

Kiwifruit has not been studied as much as other well-known fruits especially when it comes to studies about plant vigour and training systems. The aim of the study was to determine the importance of cane vigour of Actinidia chinensis var. deliciosa ‘Hayward’ and Actinidia arguta ‘Issai’ in order to develop the proper pruning technique that results in the best fruit quality. In addition, the effect of storage parameters such as weight, firmness and quality of the fruit was also studied. The study showed that the fruit size and weight are lower in low vigour canes in A. arguta, in contrast to A. chinensis, where the fruit size and weight are smaller on high-vigorous canes. For A. arguta, it is recommended to choose high-vigour canes as the optimal fruit wood during pruning. In this way, the fruits will ripen more evenly. The other possibility is to perform the harvest two to three times per season to achieve a more uniform fruit quality. In the case of A. chinensis the fruit are less variable between different cane vigour, so harvesting can be done in a single picking. In A. chinensis the less vigorous canes tend to show a slightly better fruit quality.

Assessment of Agro-Ecological Apple Replant Disease (ARD) Management Strategies: Organic Fertilisation and Inoculation with Mycorrhizal Fungi and Bacteria

Apple replant disease (ARD) impacts the economic yield of orchards by physiological and morphological suppression of apple trees on replanted soils. The complexity of replant disease caused by a plethora of biological interactions and physical properties of the soil requires complex management strategies to mitigate these effects. Based on expert recommendations, we selected two management strategies linked to agroecological principles of (a) organic fertilisation with a specific mulch composition (MDK) and (b) biofertilisation with arbuscular mycorrhizal and bacterial strains (AMFbac), applied by a composition of existing products. For both management strategies we provide a proof-of-concept, by pot and field experiments. Both treatments have the potential to mitigate ARD effects on plant vigour. ARD effect was fully mitigated by MDK treatment in the short-term (one year) and was mitigated by up to 29% after seven years of MDK treatment (long-term). MDK provides an additional substrate for root growth. AMFbac has the potential to mitigate ARD effects on plant vigour but with non-replicable plant-beneficial effects in its current form of application. Thereby our results show a principal potential to mitigate economic effects but not to overcome replant disease inducing effects. While the MDK treatment is found resource intensive but reliable, the AMFbac treatment was found more user-friendly.

Effect of Cane Vigour on the Kiwifruit Quality of A. Deliciosa and A. Arguta

Kiwifruit has not been studied as much as other well-known fruits especially when it comes to studies about plant vigour and training systems. The aim of the study was to determine the importance of cane vigour of Actinidia deliciosa 'Hayward' and Actinidia arguta 'Issai' in order to develop the proper pruning technique that results in the best fruit quality. In addition, the effect of storage parameters such as weight, firmness and quality of the fruit was also studied. The study showed that the fruit size and weight are lower in low vigour canes in A. arguta, in contrast to A. deliciosa, where the fruit size and weight are smaller on high-vigorous canes. For A. arguta, it is recommended to choose high-vigour canes as the optimal fruit wood during pruning. In this way, the fruits will ripen more evenly. The other possibility is to perform the harvest two to three times per season to achieve a more uniform fruit quality. In the case of A. deliciosa the fruit are less variable between different cane vigour, so harvesting can be done in a single picking. In A. deliciosa the less vigorous canes tend to show a slightly better fruit quality.