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Jackson Teixeira Lobo, Ítalo Herbert Lucena Cavalcante, Augusto Miguel Nascimento Lima, Yuri Alysson Carvalho Vieira, Pedro Igor Rodrigues Modesto and Jenilton Gomes da Cunha

Adequate nutritional status is fundamental for the fruiting process of mango trees (Mangifera indica L.). In this context, plant biostimulants are substances that promote physiological and nutritional changes, benefiting production. The present study evaluated the effect of biostimulants on the nutritional status and fruit production of ‘Kent’ mango trees. The experiment was carried out in the Brazilian semiarid region over 2 consecutive years, 2016 and 2017. Leaf treatments with biostimulants were applied in three phases (preflowering, beginning of flowering, and full flowering) during both seasons. The treatments were as follows: T1) control (without biostimulants); T2) biostimulants containing nutrients and L-α-amino acids; T3) biostimulants containing nutrients and Lithothamnium algae extract; T4) biostimulants containing nutrients and sucrose; and T5) biostimulants containing nutrients, free amino acids, and Lithothamnium algae extract. The results show that there was no effect of the biostimulants for chlorophyll a, b, and total indices or for total leaf soluble carbohydrates. Some of the treatments affected the leaf concentrations of N, K, Mn, Fe, and Zn, whereas only T2 in 2016 and T5 in 2017 increased the number of fruits per panicle if compared with nontreated plants. In 2016, the production per tree was higher in T5 compared with the other treatments, whereas it was greater in 2017 in both T2 and T5 with increases of 37.4 and 23.1 kg per tree, respectively, compared with the control treatment. Biostimulants containing soluble nutrients, L-α-amino acids, free amino acids, and Lithothamnium algae extract benefit the nutritional status and increase the fruit production of mango ‘Kent’.

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Robert F. Polomski

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John R. Clark, Margaret Worthington and Taunya Ernst

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Lingdi Dong, Waltram Ravelombola, Yuejin Weng, Jun Qin, Wei Zhou, Gehendra Bhattarai, Bazgha Zia, Wei Yang, Linqi Shi, Beiquan Mou and Ainong Shi

Previous investigations showed that accumulations of Na+ and Cl in leaves resulted in reductions in chlorophyll content, thereby affecting photosynthesis. Understanding how chlorophyll content evolves over time will help plant breeders to select cowpea genotypes with better tolerance to salinity by allowing them to choose those with more stable chlorophyll content under salt stress. The objective of this study was to assess how the chlorophyll content of cowpea genotypes changed over the course of 24 d of salt stress at the seedling stage. A total of 24 cowpea genotypes with different salt responses were used in this study. The experiment used a split-plot design with salt treatment as the main plot and cowpea genotypes as the subplot. In the main plot, there were two salt treatments: 0 mm (ionized water) and 200 mm NaCl. In the subplot, the cowpea genotypes were arranged as a completely randomized design with three replicates per genotype. The results revealed that: a1) the time × genotype interaction was significant under conditions with and without salt; 2) chlorophyll content slowly decreased in the salt-tolerant genotypes; 3) chlorophyll content slightly increased on day 6 and day 9 of salt stress in both moderate and sensitive genotypes, but it decreased at a faster rate than in the salt-tolerant genotypes; and 4) salt-sensitive genotypes were completely dead on day 24 of salt stress, whereas the salt-tolerant genotypes were able to maintain a significant amount of chlorophyll content. These results can be used to advance breeding programs for salt tolerance in cowpea.

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Jasim Uddain, Sanzida Islam Tripti, Mohammad Shah Jahan, Nasrin Sultana, Md Jahedur Rahman and Sreeramanan Subramaniam

The present research was undertaken with the aim of justifying the effect of morphological, physiological, and nutritional properties in organically produced zucchini squash. The experiment consisted of two factors: three levels of pruning (P0 = no pruning, P1 = primary pruning at 20 days after transplanting (DAT), and P2 = secondary pruning at 30 DAT) and four levels of vermicompost application (V0 = control, V1 = 5 t/ha, V2 = 10 t/ha, and V3 = 15 t/ha). The results demonstrated that morphological parameters, reproductive components, and yield and proximate compositions were significant differences among the treatments. Increased male and female flower production were recorded from primary pruning with 10 t/ha vermicompost treatment plots compared with control treatments. Finally, increased fruit number, individual fruit weight, fruit length, fruit diameter, total yield, carbohydrate, protein, crude fat, fiber, and ash were reported from the same treatment combination (P1V2). Taken together, 10 t/ha vermicompost with primary pruning appear to provide maximum output in terms of yield and nutrient value compared with other treatments.

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Vi Nguyen Tuong Do, Shan-Te Hsu and Yung-I Lee

The aim of this study was to develop an efficient protocol for shoot tip culture from adult plants of Paphiopedilum Pfitzer. A considerable seasonal effect on explant collection was observed in the aseptic cultures established from adult plants, including the survival and microbial contamination of explants. The shoot tip explants excised from adult plants in February and May showed higher survival and had less contamination than those explants excised in August and November. Moreover, the season of explant collection also affected the subsequent shoot forming capacity and multiplication of axillary buds. In Paphiopedilum ‘In-Charm Silver Bell’, higher shoot forming capacity was observed in February and May, whereas higher shoot multiplication was observed only in February. In Paphiopedilum ‘Hsinying Maudiae Leopard’, both February and May were optimal timing for shoot forming capacity and multiplication. We also demonstrated the effectiveness of transcinnamic acid (tCA), an antiauxin chemical in diminishing the apical dominance of shoot tip explant and thus improving the axillary bud outgrowth. In P. ‘In-Charm Silver Bell’, the addition of 100 μM tCA plus 13.3 μM 6-benzylaminopurine (BA) for 1 month promoted axillary shoot bud formation from shoot tip explants as compared with the control.

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John Rojas, Julian Quintero, Yhors Ciro and Javier Silva

The global annual production of shrimp is nearly 4.8 million metric tons, generating almost half this weight in waste. The aim of this study was to assess the development and crop production of legumes fertilized with alkaline sonicated shrimp waste under greenhouse conditions. Plants were grown separately under the following fertilization regimes: untreated soil, untreated cotton substrate, two commercial fertilizers [commercial organic fertilizer (COF) and commercial synthetic fertilizer (CSF)], and shrimp waste having hydrolysis degrees of 0%, 15%, 18%, and 25%. Electrical conductivity of shrimp-based fertilizers (SBFs) decreased with hydrolysis degree. However, pH (6.7–6.9), densification (0.2–0.3 g·cm–3) and conductivity (10–21 µS·cm–1) of soil was unaffected by fertilization. Furthermore, CSF had the greatest ionic exchange capability. Sonolysis resulted in an assimilable source of C, N, and O, mainly derived from carbohydrates and proteins, and increased the availability of minerals such as Ca and phosphate. The greatest plant growth in both legumes was achieved when treated with CSF, whereas the raw shrimp waste caused a beneficial plant growth and crop yield mainly for Phaseolus vulgaris. All fertilizers showed typical type II isotherms, and soil substrate per se exhibited the largest water uptake. The soil microbiota increased during the growing cycle and then decreased as the reproductive phase started. In fact, soil planted with Phaseolus vulgaris showed a greater microbial population than Pisium sativum. These shrimp waste hydrolysates can be used as alternative organic soil fertilizers and are suggested as substitutes for synthetic fertilizers.

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Celina Gómez, Christopher J. Currey, Ryan W. Dickson, Hye-Ji Kim, Ricardo Hernández, Nadia C. Sabeh, Rosa E. Raudales, Robin G. Brumfield, Angela Laury-Shaw, Adam K. Wilke, Roberto G. Lopez and Stephanie E. Burnett

The recent increased market demand for locally grown produce is generating interest in the application of techniques developed for controlled environment agriculture (CEA) to urban agriculture (UA). Controlled environments have great potential to revolutionize urban food systems, as they offer unique opportunities for year-round production, optimizing resource-use efficiency, and for helping to overcome significant challenges associated with the high costs of production in urban settings. For urban growers to benefit from CEA, results from studies evaluating the application of controlled environments for commercial food production should be considered. This review includes a discussion of current and potential applications of CEA for UA, references discussing appropriate methods for selecting and controlling the physical plant production environment, resource management strategies, considerations to improve economic viability, opportunities to address food safety concerns, and the potential social benefits from applying CEA techniques to UA. Author’s viewpoints about the future of CEA for urban food production are presented at the end of this review.

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Fan Cao, Xinwang Wang, Zhuangzhuang Liu, Yongrong Li and Fangren Peng

Pecan cuttings are difficult for rooting. This study describes the pecan hardwood rooting process based on anatomic characteristics to understand root formation mechanisms of pecan cuttings. The expressed proteins of different periods during the adventitious rooting process of pecan seedling hardwood cuttings were identified and analyzed to evaluate the rooting mechanism. The expressed proteins of pecan cutting seedlings were also compared with other cultivar cuttings during the rooting period. Pecan seedling cuttings were developed at different air and substrate temperatures to induce root formation. Adventitious root formation of pecan hardwood cuttings was described, and the phloem at the base of the prepared cuttings was selected as the sample for the differential protein analysis. The results showed that adventitious root formation of pecan hardwood cuttings was the only product of callus differentiation, which originated from the cells of the cambium or vascular ray parenchyma. Such adventitious root primordia were developed from those calluses that formed the regenerative structure, and the expressed proteins during the adventitious rooting of pecan hardwood cutting were identified and analyzed by matrix-assisted laser desorption ionization–time of flight–mass spectrometry (MALDI-TOF-MS) to evaluate the rooting mechanism. Eight differentially expressed proteins were found in the rooting periods, and 15 differential proteins were found by comparing pecan cutting types, which were analyzed by peptide mass fingerprinting homology. The results show that the primordial cells were differentiated from the meristematic cells. Furthermore, the differentially expressed proteins contained energy metabolism proteins, adversity stress proteins, and signal transmission proteins. The energy metabolism-related proteins were adenosine triphosphate (ATP) synthase, photosynthesis-related proteins, and enolase. The adversity-stress proteins containing heat shock-related proteins and signal transmission proteins were mainly cytochrome enzymes and heme-binding proteins. Adventitious root formation of pecan cultivar hardwood cuttings was difficult. More trials should be performed from the potential aspects of high defensive protection and phloem morphologic structure.

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Lumariz Hernandez Rosario, Juan O. Rodríguez Padilla, Desiree Ramos Martínez, Alejandra Morales Grajales, Joel A. Mercado Reyes, Gabriel J. Veintidós Feliu, Benjamin Van Ee and Dimuth Siritunga

The Solanaceae family is one of the largest and well-distributed plant families in the world. It contains species of agricultural and economical importance, such as Solanum tuberosum, Solanum melongena, Solanum lycopersicum, Nicotiana tabacum, and Capsicum annuum. In Puerto Rico, there are ≈46 species of Solanaceae of which six are endemic: Brunfelsia densifolia, Brunfelsia lactea, Brunfelsia portoricensis, Goetzea elegans, Solanum ensifolium, and Solanum woodburyi. Our objective was to use DNA barcoding to identify the Solanaceae species in Puerto Rico, including the endemics, and to assess the species relationships between them. To accomplish our objective, two chloroplast regions (psbA-trnH and matK) and a nuclear region [internal transcribed spacer (ITS)] were assessed. Pairwise distance and phylogenetic analysis demonstrate that DNA barcoding can be used to discriminate at the species level among these taxa in Puerto Rico. For all three markers, the genus that showed the highest pairwise distance between represented species was Solanum, whereas the genus that displayed the least was Capsicum. Phylogenetic trees of single and concatenated regions were generated from sequences obtained in this study and from data downloaded from the National Center for Biotechnology Information database. Our results show that this technique can be used to identify species with one, two, or three combinations of DNA barcode markers depending on the taxon. In addition, this is the first study to include the endemic species S. woodburyi in a molecular phylogenetic analysis, and it was found to have a close relationship with S. ensifolium, also endemic to Puerto Rico, and to Solanum bahamense from the Bahamas and Greater Antilles. Therefore, we suggest that S. woodburyi might be part of the Bahamense clade.