Biochemical changes in pear fruits during storage at ambient conditions

‘Patharnakh’ (PN) (Pyrus pyrifolia Burm. Nakai) and ‘Punjab Beauty’ (PB) [Pyrus communis L. × Pyrus pyrifolia Burm. (Nakai)] are leading low-chill pear cultivars of subtropics of India. Diurnal temperature and relative humidity during fruit harvest period is high which considerably affect the shelf life of fruits. Fruits of ‘PN’ and ‘PB’ pear harvested at physiological maturity were stored for 12 days at ambient temperature and effects of storage temperature on physical and qualitative parameters were studied. Both cultivars showed reduction in fruit weight and firmness, reducing sugars, sucrose, starch and pectin content. However, total soluble solids and juice acid content increased during storage. Sucrose synthase activity and sucrose content showed significant positive correlation in ‘PN’ cultivar. Activities of fruit softening enzymes such as polygalacturonase (PG) and cellulase was enhanced; whereas, pectinmethylesterase (PME) was reduced during storage. Fruit firmness was negatively correlated with PG in both the cultivars. In ‘PN’ cultivar, fruit firmness was positively correlated with cellulase and negatively with PME enzyme but reverse trend was observed in ‘PB’ cultivar. Fruit minerals content didn’t show any substantial disparities in both the cultivars during storage. ‘Patharnakh’ and ‘Punjab Beauty’ fruits maintain desirable quality parameters up to 6-9 days and 3-6 days, respectively, during storage at ambient conditions.

Comparison of wild and domesticated hot peppers fruit: volatile emissions, pungency and protein profiles

Capsicum plant species are globally cultivated in warm and temperate regions, being important for agro-economic, biological and cultural aspects. While their worldwide spread and their ability of cross-pollination to easily hybridize play an important role in the formation of numerous species and varieties but also create confusion for their classification. For this reason, the categorization of species and varieties is complex and several methods have been used to evaluate pepper plant origin and evolution. Therefore, the objectives of this study were to compare a wild pepper (Capsicum chacoense) with other two domesticated cultivars belonging to different species such as Capsicum annuum and C. baccatum and draw conclusions about their origins using different approaches. For this purpose three methodologies have been used and compared: the comparison of their fruits volatile organic compounds (VOCs) emissions , their capsaicin and dihydrocapsaicin content and the leaves proteomic profiles. The VOCs analysis has been conducted by a time-of-flight mass spectrometry (ToF-MS) with an innovative approach to better identify all the compounds detected, in particular using two different ionization agents (H3O+ and NO+) to better identify all the compounds detected. The VOCs and pungency analyses were then used to build back propagation neural networks (BPNN) and a Random Tree classifier to conduct a multivariate analysis and evaluate the most species-specific volatiles. The outcomes appeared to be a most accurate approach with respect to the traditional varieties descriptors used for peppers discrimination. The BPNN led to the identification of several putative volatiles as good candidates for the recognition of these species or significant nodes in a decision learning tool. Finally, protein profiles have been obtained by SDS-PAGE analysis on the leaves to perform a fast proteomic comparison among the species. The protein profiles showed the C. baccatum and C. chacoense were more similar to the domesticated pepper C. annuum.

Investigation of modified WPM medium for the best meristem proliferation of Corylus avellana L.

Cultivation of Corylus avellana L. in Turkey is performed generally in the northern regions where it is an important source of livelihood for the local farmers. More than 70% of world hazelnut production is supplied by Turkey, but compared with other countries, Turkey’s hazelnut production area is quite narrow. In this study was aimed to develop an effective in vitro production for seven local cultivars of C. avellana. Therefore, WPM medium supplemented with 6-Benzylaminopurine (BAP) was modified by using single or in combination of Fe-EDDHA, AgNO3, H3BO3, charcoal and gibberellic acid. In all varieties, the best regeneration rates varying between 68% and 94% were obtained from WPM medium supplemented with 4.4 µM BAP, 27.8 µM Fe-EDDHA and 10g/L Charcoal. Genetic stability of shoots derived from meristem culture using the best medium was analysed using ISSR primers, when the gel images of the PCR products were examined, no polymorphic band was observed in samples collected from seven provinces, and the genetic stability was determined as 100%.

Genetic diversity and trait profiles of some Amaranthus genotypes

Knowledge of the pattern of trait variation among accessions, and the trait profiles of the accessions is crucial for improvement of a crop. Twenty-one Amaranthus accessions were evaluated in 2018 and 2019 to investigate the extent of genotypic diversity among the amaranth accessions and their trait profiles. Data were subjected to analysis of variance, and correlation and principal component analyses. Taking stem weight (SWT) as the yield, the accession × yield-trait combination (GYT) biplot was employed to investigate the trait profiles of the accessions. Accession, year, and accession × year mean squares were significant (P≤0.05/0.01) for most of the measured traits. The first three principal components explained 88.18% of observable variation among the accessions and identified plant height (PHT), number of leaves per plant (NOL), and root weight (RWT) as the major contributors. Significant (P≤0.01) correlation was observed in the association of SWT with NOL, TBM, and RWT. Accessions NGB00019 and NGB00061 were associated with the sector containing all the YT combinations considered. However, NGB00019 was identified as the best combiner of yield with other traits. Further studies involving more traits should determine the trait profiles of the remaining accessions.

Artificial medium for in vitro pollen germination of some ornamental Linum species

For the first time components of the nutrient medium were identified for the successful germination of pollen in such ornamental species of the Linum genus as L. grandiflorum, L. hirsutum, L. pubescens and L. thracicum. It was shown that the media with PEG-2000 in concentrations of 20-30% in combination with boric acid and calcium chloride in the concentrations of 200 mg/l ensure germination of Linum pollen up to 40-50%. The addition of sucrose and PEG with higher molecular weight adversely affects the germination of pollen. This will allow anyone to evaluate the quality of flax pollen quickly and efficiently and more successfully implement many genetic and breeding programs.

Effect of vine and fruit pruning on yield attributes of two watermelon (Citrullus lanatus) cultivars

This study was carried out to determine the effect of vine and fruit pruning on watermelon (Citrullus lanatus) yield. Five pruning methods: P1=no pruning at all, P2=pruning to four vines with two fruits per vine, P3=pruning to four vines with one fruit per vine, P4=pruning to three vines with two fruits per vine and P5=pruning to three vines with one fruit per vine were evaluated on two watermelon cultivars: ‘Sugar baby’ and ‘Julie F1’ under a factorial randomized complete block design with three replications. Investigations were carried out in the seasons 2017A (short rains) and 2017B (long rains) at Karama and Rubona experimental sites belonging to Rwanda Agriculture and Animal Resources Development Board. The obtained results indicated a significant difference among the different cultivars and pruning methods tested during both seasons and at two sites. Generally, all studied parameters recorded higher values during season 2017B than in season 2017A at Rubona site. A similar trend was recorded at Karama site except that the fruit yield per plant and per hectare for plants which were pruned to three vines with one fruit reduced during season 2017B as compared to season 2017A. The highest number of fruits per plant, fruit weight, fruit yield per plant and per hectare was recorded in ‘Julie F1’ compared to ‘Sugar baby’ at both sites and during both seasons. Higher fruit weight was obtained when both cultivars were pruned to three or four vines with one fruit per vine. Higher number of fruits per plant and higher fruit yield per plant was observed under pruning to four vines with two fruits per vine at Rubona site; while at Karama site, higher fruit yield per plant was recorded under pruning to three vines with one fruit or two fruits per vines and pruning to four vines with two fruits per vine. A similar trend was observed in fruit yield per hectare. Based on results of the current study, cultivation of the hybrid ‘Julie F1’ and pruning to three vines with one fruit per vine is recommended for optimum watermelon yield with big-sized fruits.

Prospects for improvement of Plectranthus edulis (Vatke) Agnew: A high potential food security crop

Plectranthus edulis (Vatke) Agnew is a tuber crop originated and cultivated in Ethiopia for food and medicinal uses. It has higher quality nutrient composition than other tuber crops. The cultivation of P. edulis is under threat because of introduction of exotic species, land use change, habitat destruction, population pressure, selection of only few local varieties by farmers and climate change. Although P. edulis is a high potential food security crop, there is no any improved variety as there has been very little research on the crop. This lack of research attention including absence of improved varieties and lack of conservation strategy may lead to significant genetic erosion of this crop. Previous studies of P. edulis include documentation of indigenous knowledge, analysis of nutritional composition and the use of its starch in drug formulation, traditional cultivation practices, micropropagation, in vitro regeneration, and morphological and molecular genetic diversity. However, more extensive research in all aspects is required for its improvement, use and conservation. Therefore, it is imperative to review the research results of this crop for the research community. This article reviewed research findings of this crop and presents it in a comprehensive way so that the readers will get ample information and can refer original research findings for the details.

Genetic diversity in Colocasia esculenta and Xanthosoma mafaffa in Togo, West Africa

Taro and new cocoyam are root and leaf crops commonly grown in tropical to warm temperate regions. In Togo, they are neglected and underutilised. Here we report the genetic diversity of 26 accessions of taro and 101 accessions of new cocoyam. Analysis of simple sequence repeats revealed low polymorphic information content of 0.43 and 0.25 in taro and new cocoyam, respectively. PCA scatterplots and Neighbour Joining dendrograms based on the SSR data clustered accessions into groups that more-or-less correspond to morphological diversity in both species. AMOVA within and between morphological groups revealed greater variances within groups than between. This indicates weak genetic differentiation between morphological groups, particularly for taro. Genetic diversity was greater among taro cultivars. Taro has a longer history of introduction and dispersal in Africa, and has had more opportunity for multiple introduction and local cultivar development. Different strategies are suggested for future development of these crops in Togo and Africa. For taro, further studies of existing diversity and recent experimental introduction, has spread widely in Africa with little genetic diversity. For this crop, international collaboration is needed to clarify taxonomy, and to introduced further cultivars for evaluation under local conditions in Africa.

Effect of growth temperature levels on photosynthetic ability and fruit quality of ‘KU-PP2’, a new low-chill peach cultivar

Temperature is a crucial factor in growing plants in a forcing system. Our goal was to introduce low-chill peach cultivars into a forcing culture for early-season peach production with high fruit quality. However, the effects of growth temperature on plant growth and fruit quality during fruit development of the ‘KU-PP2’ peach cultivar have not yet been evaluated. ‘KU-PP2’ trees were grown in containers and transferred to phytotrons after fruit set in April 2019. The air temperature was set at 20, 25, and 30°C until harvest. Photosynthetic ability, leaf characteristics, and fruit quality under each treatment were determined. Long exposure to lower growth temperatures did not cause a change in leaf characteristics or a reduction in photosynthetic ability and fruit quality in the ‘KU-PP2’ peach cultivar. In contrast, the 30°C was found to be associated with a decrease in leaf size and thickness, stomatal density, photosynthesis, chlorophyll content, and fruit size. Conversely, the high-temperature condition enhanced coloration of the fruit peel and hastened the harvesting period, compared with the lower-temperature treatments. These results indicated that long-term exposure to the moderately high temperature of 30°C negatively affected plant growth and fruit productivity through changed leaf characteristics and a disrupted photosynthesis.

Genetic diversity assessment of ancient mulberry (Morus spp.) in Lebanon using morphological, chemical and molecular markers (SSR and ISSR)

Lebanon has ancient mulberry trees which are the remnants of the abundant orchards that dominated its lands during the nineteenth century. Lebanese mulberry germplasm has not been assessed yet. This study aims to collect local old rainfed mulberry accessions from different geographical regions and assess their diversity by using morphological and molecular markers (SSR and ISSR). Genetic diversity of 70 accessions of mulberry were evaluated by using 27 morphological traits. The dendrogram based on the morphological attributes showed a relative separation of the different accessions based on fruits color and taste. Molecular analysis was performed for the accessions by using selected SSR and ISSR primers. The primers marked a high discriminating power (0.7 to 0.89). The dendrogram constructed on the base of UPGMA method showed 13 different groups. The clustering patterns indicated no location nor local name specificity among mulberry accessions. The combination of SSR and ISSR primers was informative for estimating the extent of mulberry genetic diversity. It can be concluded that there is a high level of genetic diversity within mulberry trees in Lebanon. These results will be useful for mulberry germplasm management in terms of biodiversity protection and as a valuable source of gene pool for crop improvement.