Supplying atmospheres with partial pressures of O 2 as low as 0.4 kPa in combination with up to 5 kPa CO 2 has proved an effective alternative to the use of post-harvest chemical treatments, e.g. diphenylamine, for control of superficial scald in 'Bramley's Seedling' apples. However, the use of such 'extreme' CA conditions has occasionally caused injury to the skin and the flesh of the fruit, and the risk of injury holds back use of these techniques to replace chemical treatments. Working on the hypothesis that such injury is caused by a transient high CO 2 concentration in the fruit shortly after store loading, we investigated the effect of delaying establishment of such 'extreme' CA conditions on the subsequent development of CO 2 -injury. 'Bramley's Seedling' apples were cooled at a typical commercial rate and subjected to a 20-day treatment with CO 2 at 5, 10 or 20 kPa (in 1 kPa O 2 ) established by flushing at 0, 5, 10, 15 and 20 days after loading. The incidence of external CO 2 -injury in fruit treated with 5, 10 and 20 kPa CO 2 decreased following a 0, 5 and 10 day delay respectively and a 20-day delay resulted in less than 5% of injured fruits at the most damaging CO 2 concentration (20 kPa), compared with 83% damaged fruits when flushed at day 0 (i.e. no delay). Internal CO 2 -injury responded in a similar way to external injury, although the flesh was generally less susceptible to injury than the skin. A 5-day delay in sealing CA containers was sufficient to prevent external and internal CO 2 -injury where 5 kPa CO 2 (in 1 kPa O 2 ) was established by fruit respiration as opposed to flushing, although this result was achieved in a year of low potential for CO 2 -injury. The incidence of external and internal injury varied according to the source of fruit. High resistance to gas diffusion was associated with increased internal injury but was not related to the extent of external injury. The application of diphenylamine prior to establishment of the most damaging treatment (20 kPa CO 2 at day 0) gave complete protection against skin injury and partial protection against internal damage.
A diverse assemblage of insect visitors can provide functional complementarity within plant pollination due to differences in characteristics such as their physical traits, visitation rate and foraging time of day or year. In a horticultural context, greater functional complementarity may play a crucial role in enhancing fruit yield and quality by improving pollination. We tested whether the identity of the crop pollinators (bumblebee Bombus terrestris and hoverfly Eupeodes corollae) independently and additively influenced commercial strawberry yield, quality, and nutritional parameters such as vitamin C and sugar concentration. Fragaria x ananassa “Malling Champion” plants received pollination treatments of either a) “control”: self-pollination where pollinators were excluded, b) “bee”: bumblebee Bombus terrestris, c) “hoverfly”: Eupeodes corollae, d) “combined”: both B. terrestris and E. corollae. Hoverflies and bumblebees exhibited distinct visitation patterns throughout the day, establishing a functional complementary relationship that enhances pollination success and crop output as well as vitamin C concentrations. Strawberries from plants receiving pollination by bumblebees, or bumblebees and hoverflies combined, had higher yields of higher marketable quality. They also had measurably higher vitamin C content than strawberries from plants pollinated by hoverflies alone, or the control (self-pollinating) plants. This study advances our understanding of niche complementarity and its impact on fruit yield and quality. By elucidating the behavioural and temporal dynamics of pollinators, we provide valuable insights for optimizing pollination strategies in agricultural contexts. Our findings highlight the significance of behavioural factors, such as handling time and number of visits, in determining fruit quality.
Abstract African yam bean (AYB; Sphenostylis stenocarpa ) is an underutilized legume indigenous to Africa with great potential to enhance food security and offer nutritional and medicinal opportunities. However, low grain yield caused by fungal diseases, including pod blight and leaf tip dieback, deters farmers from large‐scale cultivation. To determine the prevalence of fungal diseases affecting leaves, pods and flowers of AYB, a survey was conducted in 2018 and 2019 in major AYB‐growing areas in Nigeria. Leaf tip dieback, flower bud rot and pod blight were the most common symptoms. Morphological and molecular assays were conducted to identify the causal agents of the observed diseases. In all the samples examined, fungi from eight genera were isolated from diseased leaves, buds and pods. Koch's postulates were fulfilled only for fungi belonging to the Colletotrichum genus. Fungi from the other seven genera did not produce disease symptoms in healthy AYB tissues. Several Colletotrichum isolates were characterized by sequencing the rDNA internal transcribed spacer (ITS), glyceraldehyde‐3‐phosphate dehydrogenase , calmodulin and ApMAT loci. A combined phylogenetic analysis revealed four Colletotrichum species: C . siamense , C . theobromicola and C . fructicola , which were recovered from diseased leaves, and C . truncatum , recovered from diseased pods and buds. Our results are useful to gear efforts to develop integrated management strategies to control diseases affecting AYB in Nigeria and elsewhere. Availability of such strategies may stimulate greater AYB cultivation, which can contribute to diet diversification, something repeatedly advocated by a range of stakeholders to increase food security and prosperity of smallholder farmers.
Abstract Background : Fruit firmness and in particular the individual components of texture and moisture loss, are considered the key quality traits when describing blueberry fruit quality, and whilst these traits are genetically regulated, the mechanisms governing their control are not clearly understood. In this investigation, RNAseq was performed on fruits of two blueberry cultivars with very different storage properties, ‘Bluecrop’ and ‘Legacy’, at harvest, three weeks storage in a non-modified environment at 4 o C and after three weeks storage at 4 o C followed by three days at 21 o C, with the aim of understanding the transcriptional changes that occur during storage in cultivars with very different post-harvest fruit quality. Results : De novo assemblies of the transcriptomes of the two cultivars were performed separately and a total of 39,335 and 41,896 unigenes for ‘Bluecrop’ and ‘Legacy’ respectively were resolved. Differential gene expression analyses were grouped into four cluster profiles based on changes in transcript abundance between harvest and 24 days post-harvest. A total of 264 unigenes were up-regulated in ‘Legacy’ and down-regulated in ‘Bluecrop’, 103 were down-regulated in ‘Legacy’ and up-regulated in ‘Bluecrop’, 43 were up-regulated in both cultivars and 355 were down-regulated in both cultivars between harvest and 24 days post-harvest. Unigenes showing significant differential expression between harvest and following post-harvest cold-storage were grouped into classes of biological processes including stress responses, cell wall metabolism, wax metabolism, calcium metabolism, cellular components, and biological processes. Conclusions : In total 21 differentially expressed unigenes with a putative role in regulating the response to post-harvest cold-storage in the two cultivars were identified from the de novo transcriptome assemblies performed. The results presented provide a stable foundation from which to perform further analyses with which to functionally validate the candidate genes identified, and to begin to understand the genetic mechanisms controlling changes in firmness in blueberry fruits post-harvest.
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