Morphological and Physiological Characterization of Sweetpotato Roots after Skinning

Sweetpotato is an important staple crop, and a supplementary source of nutrients; minerals, carbohydrates, and vitamins, for the food industry. Quality of sweetpotatoes depends on cultivar, preharvest management practices, and harvest equipment causing skinning. Information on morph-physiological characteristics of storage roots is needed for preharvest management decisions, cultivar selection, and application of harvest aids and harvesting procedures for postharvest storage durability of sweetpotatoes. Also, devices to measure skinning properties of storage roots are needed. This research was conducted to measure skin toughness of various sweetpotato cultivars. The number of skin layers was determined using fluorescent microscopy, and lignin content was determined with the Near Infrared System. Preharvest cultural practices, such as devining to enhance skin set and lignin content, were applied 1, 3, 7 days preharvest, and Ethephon at the rate of 1.68 ha-and 0.84 kg ha-1 applied at 1, 3, and 7 days preharvest. In addition, curing to enhance skin healing and lignin content was evaluated. This research was conducted in the field and in the greenhouse environments. The force gauge and the torquometer were the most accurate and precise devices to measure the force needed to break the skin of the various sweetpotato cultivars. The cultivars, “L07-6R”, “L07-146”, and “Beauregard-14” had the toughest skin compared to the other cultivars. However, “Covington” and “Hatteras” had the highest lignin content. Fluorescent microscopy showed that the cultivars “L07-6R” and “L07-146” had 12 and 10 cell layers, respectively, and the treatment of Ethephon at 1.68 Kg∙ha-1 3 days and 7 days before harvest resulted in the highest lignin content in the skin. Divining 3 days preharvest, and applying Ethephon at 0.84 kg∙ha-1 at 1day and 3days preharvest resulted in the highest lignin content. In addition, the treatments with Ethephon at 1.68 Kg∙ha-1 applied at 3 days and 7 days preharvest resulted in the hardest skin as indicated by torquometer and the force gauge. Curing for 7 days resulted in higher lignin content compared to the others pretreatments. When wounded and cured for 7 days, the healing process was enhanced greatly, resulting in rapid skin set of sweetpotato storage roots

Insights into the Interaction of Copper Oxide Nanoparticles with Sweetpotato (Ipomoea batatas (L.) Lam.): The Role of Lignin on Copper Uptake and Translocation

Sweetpotato [Ipomoea batatas (L.) Lam.] is widely cultivated in many countries worldwide. The world production of sweetpotato is around 127 billion tons and it is ranked seventh in the world as a staple food. After harvesting, sweetpotato storage roots are treated with fungicides to prolong shelf life. Lignin plays an important role in the conservation of the storage roots. One of the practices to activate the lignification pathway is called “curing process.” The roots are placed under 80% relative humidity at a temperature of 29 °C for a period of 7 to 15 days, followed by a cooling period at 10 - 18 °C. Until recently, storage roots were protected against pathogens by using the fungicide dicloran, but foods with dicloran residues are no longer accepted in many markets including infant foods, organic foods, and exports. Thus, other fungicides, including copper, have been used. Thus far, only ionic copper compounds had been utilized to protect the plants against the fungus diseases in crop fields; therefore, new copper products—including the nano forms—may have great potential to be used to preserve the quality of the plants in open fields and the roots in shelves. Currently, there is a lack of information concerning the interaction of copper-based engineering nanomaterials (ENMs) with the skin components of the roots, the lignin content, and the interaction with the physiological process like chlorophyll content, photosynthesis, and carbohydrates production. The objectives of this study were: (1) to determine the effects of curing and lignin content of the periderm in the retention of copper ions/particles, and (2) to study the physiological effects of copper oxide (CuO) nanoparticles or compounds in sweetpotato plant growth and production. This study was performed in two phases. In phase I, commercial roots of Beauregard-14, low lignin content) and Covington (COV, high lignin content) were exposed to CuO nanoparticles (nCuO), bulk CuO (bCuO) and copper chloride (CuCl2) at the concentration of 0-125 mg/L, before and after curing. After treatment, root tissues were analyzed by inductively coupled plasma-optical emission spectroscopy (ICP-OES) or scanned with a two-photon microscope to study the possible penetration of Cu particles into the storage root tissues. At 25 mg/L, only bCuO showed higher Cu concentration in the periderm and cortex of B -14 (2,049 mg/kg and 76 mg/kg before curing; 6,769 mg/kg and 354 mg/kg after curing, respectively) and in cortex of COV (692 mg/kg before curing and 110 mg/kg after curing), compared with controls (p ≤ 0.05). In medulla, the most internal tissue, only B-14 exposed to 125 mg/L bCuO showed significantly (p ≤ 0.05) more Cu before curing (17 mg/kg) and after curing (28 mg/kg), compared with control (p≤ 0.05). In Phase II, slips from the two varieties were planted in plastic pots containing 3 kg of soil each amended with the three copper compounds at 25, 75, and 125 mg/kg and cultivated under full sun exposure. Gas exchange parameters, root production, and nutritional composition of the roots were evaluated at the physiological maturity of the plants. After harvesting, roots were classified by size and analyzed for nutrient element contents or changes in macromolecules. The interaction of copper compounds with photosynthesis showed that the higher variance was due to differences in lignin content between varieties. The ICP-OES data showed no increase of Cu in medulla, except for B-14 plants exposed to CuCl2 at 125 mg/kg, which had 622% more Cu in medulla, compared with control (p ≤ 0.05). The fresh weight of B-14 storage roots was higher in plants exposed to bCuO at 75 and 125 mg/kg, compared with nCuO at 125 mg/kg, but there were no differences with control. The root length was increased by nCuO at 25 mg/kg in COV, compared with the other treatments. None of the treatments affected the protein content in storage roots. The sugar content was significantly increased by 75 mg/kg nCuO by 140%, respect to the control (p ≤ 0.05). Starch was reduced by 71% in B-14 and by 80% in COV roots exposed to bCuO at 25 mg/kg). Additionally, at 125 mg/kg, bCuO and CuCl2 showed a reduced number of starch grains per sample, and most of them were misshaped. The prospective use of nCuO during root curing, plus the increase in sugar and root length on soil grown plants suggest that nCuO may represent a good alternative to protect sweetpotato plants during cultivation and increase the shelf life of the roots

Caracterización y evaluación preliminar de los cultivares de tomate (Lycopersicum esculentum willd) y aspectos agronómicos utilizados en Tisma

En este estudio se realizó una caracterización y evaluación preliminar de los cultivares de tomate Rio Grande, Romo y Chilca, y los aspectos agronómicos utilizado en Tisma, Así como de los métodos empleados en la selección de semilla. Se determinó que en el cultivar Rio Grande existe una menor variedad dentro de sus características morfológicas y un mayor porcentaje de fructificación y con cualidades para el procesamiento industrial, no siendo así el cultivar Romo y Chilca que presentaron en una heterogeneidad para los indeterminados, con frutos de características para el consumo fresco pero con una variabilidad bien marcada, presentando un potencial para trabajos de selección. En el uso agroquímicos existente diferencias bien marcadas ente los productores muestreados por la frecuencia de las aplicaciones y el uso de pesticidas provocándose en la zona un desequilibrio en la lucha contra las plagas y enfermedades. Otro aspecto importante es el método de selección de la semilla ya que ellos se autoabastecen de semilla seleccionado al momento del tercer corte sin hacer una previa selección de las ‘plantas en el campo, facilitando la transmisión de patógenos que disminuyen los rendimientos considerablemente

Effect of copper oxide nanoparticles on two varieties of sweetpotato plants

Little information is available on the interaction of CuO nanoparticles (nCuO) with tuberous roots.In this study,Beauregard-14(B-14,lowlignin) and Covington COV,highlignin) sweet potato varieties were cultivated until maturity in soil amended with nCuO,bulk copper oxide(bCuO)andCuCl2at25–125mg/kg.TheCu treatments hadno significant influence on chlorophyll content.Gase xchangeparameterswerenotaffectedinB-14.InCOV,however,at125mg/kgtreatments,bCuO reducedtheintercellularCO2(11%),whileCuCl2increaseditby7%,comparedwithcontrol(p≤0.035).At25mg/kgnCuOincreasedthelengthofCOVroots (20.7 ± 2.0cmvs.14.6 ± 0.8cm,p≤0.05).InperidermofB-14,nCuO,at125mg/kg,increasedMgby232%,whiletheequivalentconcentrationofCuCl2 reducedPby410%,comparedwithcontrol(p≤0.05).ThedatasuggestthepotentialapplicationofnCuOasnanofertilizerforsweetpotatostoragerootproduction