Agronomy, Volume 8, Issue 9 (September 2018) – 39 articles

The total or partial removal of sugarcane (Saccharum spp. L.) straw for bioenergy production may deplete soil quality and consequently affect negatively crop yield. Plants with lower yield potential may present lower concentration of leaf-tissue nutrients, which in turn changes light reflectance of canopy in different wavelengths. Therefore, vegetation indexes, such as the normalized difference vegetation index (NDVI) associated with concentration of leaf-tissue nutrients could be a useful tool for monitoring potential sugarcane yield changes under straw management. Two sites in São Paulo state, Brazil were utilized to evaluate the potential of NDVI for monitoring sugarcane yield changes imposed by different straw removal rates. The treatments were established with 0%, 25%, 50%, and 100% straw removal. The data used for the NDVI calculation was obtained using satellite images (CBERS-4) and hyperspectral sensor (FieldSpec Spectroradiometer, Malvern Panalytical, Almelo, Netherlands). Besides sugarcane yield, the concentration of the leaf-tissue nutrients (N, P, K, Ca, and S) were also determined. The NDVI efficiently predicted sugarcane yield under different rates of straw removal, with the highest performance achieved with NDVI derived from satellite images than hyperspectral sensor. In addition, leaf-tissue N and P concentrations were also important parameters to compose the prediction models of sugarcane yield. A prediction model approach based on data of NDVI and leaf-tissue nutrient concentrations may help the Brazilian sugarcane sector to monitor crop yield changes in areas intensively managed for bioenergy production. Full article

To determine if current university fertilizer rate and timing recommendations pose a limitation to high-yield corn (Zea mays subsp. mays) and soybean (Glycine max) production, this study compared annual Phosphorous (P) and Potassium (K) fertilizer applications to biennial fertilizer applications, applied at 1× and 2× recommended rates in corn–soybean rotations located in Minnesota (MN), Iowa (IA), Michigan (MI), Arkansas (AR), and Louisiana (LA). At locations with either soil test P or K in the sub-optimal range, corn grain yield was significantly increased with fertilizer application at five of sixteen site years, while soybean seed yield was significantly increased with fertilizer application at one of sixteen site years. At locations with both soil test P and K at optimal or greater levels, corn grain yield was significantly increased at three of thirteen site years and soybean seed yield significantly increased at one of fourteen site years when fertilizer was applied. Site soil test values were generally inversely related to the likelihood of a yield response from fertilizer application, which is consistent with yield response frequencies outlined in state fertilizer recommendations. Soybean yields were similar regardless if fertilizer was applied in the year of crop production or before the preceding corn crop. Based on the results of this work across the US and various yield potentials, it was confirmed that the practice of applying P and K fertilizers at recommended rates biennially prior to first year corn production in a corn–soybean rotation does not appear to be a yield limiting factor in modern, high management production systems. Full article

To improve sustainability of agriculture, high yielding crop varieties with improved water use efficiency (WUE) are needed. Despite the feasibility of assessing WUE using different measurement techniques, breeding for WUE and high yield is a major challenge. Factors influencing the trait under field conditions are complex, including different scenarios of water availability. Plants with C₃ photosynthesis are able to moderately increase WUE by restricting transpiration, resulting in higher intrinsic WUE (iWUE) at the leaf level. However, reduced CO₂ uptake negatively influences photosynthesis and possibly growth and yield as well. The negative correlation of growth and WUE could be partly disconnected in model plant species with implications for crops. In this paper, we discuss recent insights obtained for Arabidopsis thaliana (L.) and the potential to translate the findings to C₃ and C₄ crops. Our data on Zea mays (L.) lines subjected to progressive drought show that there is potential for improvements in WUE of the maize line B73 at the whole plant level (WUE_plant). However, changes in iWUE of B73 and Arabidopsis reduced the assimilation rate relatively more in maize. The trade-off observed in the C₄ crop possibly limits the effectiveness of approaches aimed at improving iWUE but not necessarily efforts to improve WUE_plant. Full article

The global demands for various grains, including durum wheat (Triticum turgidum L. subsp. durum (Desf.) Husn.), are expected to increase substantially in the coming years, due to the ever-growing human population’s needs for food, feed, and fuel. Thus, providing consistent or increased durum grain to the world market is one of the priorities for policy-makers, researchers, and farmers. What are the major achievements in agronomic advancement for durum wheat cultivation in recent decades? How might the current cropping systems be improved to increase crop yield and quality and improve resource use efficiencies while minimizing input costs and decreasing negative impact on the environment? Canada is one of the major durum wheat producers in the world, as Canada contributes about 50% to global trade of durum grain. Canada’s research achievements in durum wheat might serve as a guide for advancing the cultivation of the crop in other regions/countries on the planet. This review summarizes the major Canadian research findings in the aspects of durum wheat agronomics during the period 2001 to 2017 years. It highlights the main advancements in seeding and tillage, crop rotation and diversification, and use of pulse-induced microbiomes to improve soil health and feedback mechanisms. The genetic gain and breeding for resistance against abiotic and biotic stresses are discussed. Finally, we identified the main constraints and suggested some near-term research priorities. The research findings highlighted in this review will be of use for other areas on the planet to increase durum wheat productivity, improve soil fertility and health, and enhance long-term sustainability. Full article

Crop producers transitioning to an organic cropping system must grow crops organically without price premiums for 36 months before certification. We evaluated red clover-maize, maize-soybean, and soybean-wheat/red clover rotations in organic and conventional cropping systems with recommended and high inputs in New York, USA to identify the best rotation and management practices during the transition. Organic compared with conventional maize with recommended inputs in the maize-soybean rotation (entry crop) averaged 32% lower yields, $878/ha higher production costs, and $1096/ha lower partial returns. Organic maize compared with conventional maize with recommended inputs in the red clover-maize rotation (second transition crop) had similar yields, production costs, and partial returns. Organic compared with conventional soybean with recommended inputs in soybean-wheat/red clover or maize-soybean rotations had similar yields, production costs, and partial returns. Organic compared with conventional wheat with recommended inputs in the soybean-wheat/clover rotation had similar yields, $416/ha higher production costs, and $491/ha lower partial returns. The organic compared with the conventional soybean-wheat/red clover rotation had the least negative impact on partial returns during the transition. Nevertheless, all organic rotations had similar partial returns ($434 to $495/ha) so transitioning immediately, regardless of entry crop, may be most prudent. High input management did not improve organic crop yields during the transition. Full article

The pollen development of male-sterile lines should be conducted during the high temperature season to ensure the sterility of male-sterile line pollen and the safety of hybrid seed production in the breeding of thermosensitive genic male-sterile (TGMS) lines of early rice. However, the mature hybrid rice seeds are prone to pre-harvest sprouting (PHS) during hot, rainy days, which leads to the decrease of hybrid rice seed quality or a loss of utilization value. In this study, with an aim to bring a dormancy trait from the dormant genotype to the current low-dormant TGMS lines, a common wild rice “Chaling” (Oryza rufipogon), which has strong seed dormancy, a large black stigma, and a high exsertion rate, was hybridized with the early rice TGMS line “Zhu 1S,” which often exhibits PHS. After screening for early maturing and seed dormancy, the early rice “Yezao S” and “Yezhuzao S,” with the characteristic of seed dormancy, were selected. The critical temperature of high temperature sterility for these two male-sterile lines was below 23.5 °C. The stigma of “Yezao S” was black and its exsertion rate was 79.9%, while “Yezhuzao S” had a colorless stigma with an exsertion rate of 76.8%. The expression of the genes OsNCEDs in “Yezao S” and “Yezhuzao S” were significantly higher than that in “Zhu 1S” the 15th day after heading, and the abscisic acid (ABA) content was also higher than that of “Zhu 1S” the 20th day after heading. The results indicated that introducing the dormancy characteristics from wild rice “Chaling” into the early rice TGMS lines was an effective way to prevent PHS. Full article

The three main farm products from Canadian agriculture, i.e., proteins, vegetable oils, and carbohydrates, account for 98% of the land in annual crops in Canada. The intensities and efficiencies of these field crops in relation to their Greenhouse Gas (GHG) emissions were assessed for their value as land use change indicators. To facilitate spatial comparisons, this assessment was carried out at the Ecodistrict (ED) scale. The Unified Livestock Industry and Crop Emissions Estimation System (ULICEES) model was modified to operate at the ED scale, and used to quantify the GHG emission intensity of protein. GHG emissions were also calculated for plant products not used for livestock feed. The livestock GHG emissions and GHG-protein intensities estimated using ED scale inputs to ULICEES were reasonably close to GHG-protein intensities generated by the version of ULICEES driven by provincial scale census data. Carbohydrates were split into two groups, i.e., whether or not they supported livestock. Annual farm product data at 5-year intervals were used to generate GHG emissions from all farm operations. The range of GHG emissions from all farm operations in Western Canada was from 42 to 54 Mt CO2e between in 1991 and 2011, while GHG emissions from livestock ranged from 22 to 34 Mt CO2e over the same period. The Eastern Canadian GHG emissions from all farm operations declined gradually from 24 to 22 Mt CO2e over the period, with most of the eastern GHG emissions being from livestock. Ruminant livestock accounted for most of the livestock GHG emissions, particularly in the west. Provincial scale GHG emission efficiencies of the four farm product groups were assessed on a per-unit of GHG emissions basis for 2006. The most GHG-efficient province for protein was Ontario, whereas the most GHG-efficient province for all three plant products was Saskatchewan. The coastal provinces were the least GHG-efficient sources of all four farm product groups. Full article

In recent years, awareness on sustainable land use has increased. Optimizing the practice of nitrogen fertilization has become crucially imperative in cropping management as a result of this current trend. The effort to improve the availability of organic nitrogen has incurred a bottleneck while seeking to achieve a high yield and quality performance for organic winter cereals. Field experiments were conducted, under rainfed Mediterranean conditions, over a period of two subsequent growing seasons. The objective was to investigate the effect of soil and foliar S application on the performance of three durum wheat cultivars fertilized with either organic or inorganic N. The hypothesis to be verified was if different S fertilization strategies could improve grain yield and quality when coupled with mineral or organic N fertilizer. There were three levels of treatment with mineral N fertilizer (120, 160 and 200 kg ha⁻¹), two levels of organic N fertilizer (160 and 200 kg ha⁻¹), two levels of S fertilizer applied to the soil (0 and 70 kg ha⁻¹), and two levels of foliar S application at flag leaf stage (0 and 5 kg ha⁻¹). Cultivars were Dylan, Iride and Saragolla. Analyzed traits were grain yield, yield components and quality features of grain. Overall, at the same N rate, grain yield and quality were markedly higher for mineral than organic N source. Cultivar × Year × N treatment interactions significantly affected grain yield and quality indices. Iride showed a high yield stability throughout the mineral N rates in the most favorable year (2011) and, in the same year, was the top performing cultivar in organic N treatments. Dylan was the top performing cultivar for protein content, while Saragolla for the SDS sedimentation test. Soil S fertilization had no effect on grain quality, whereas it significantly increased grain yield (+ 300 kg ha⁻¹) when coupled with organic rather than a mineral N source. However, foliar S application at flag leaf stage did not affect grain yield, but it significantly enhanced quality indices such as test weight (81 vs. 79.9 kg hL⁻¹), protein content (13.7% vs. 12.9 %) and SDS value (72.5 vs. 70.5 mm). A rate of 160 kg ha⁻¹ of N (both mineral and organic) determined the optimal response for both grain yield and quality. Finally, soil and foliar application of S may help to contain the large yield and quality gap that still exists between mineral and organic fertilization of durum wheat. Full article

Improvement of nitrogen use efficiency is of great importance in maize (Zea mays L.) production. In the present study, an eco-friendly growth substance, polyaspartic acid (PASP), was applied to maize seedlings grown with different nitrate (NO₃⁻) doses by foliar spraying, aimed at evaluating its effects on maize nitrogen assimilation at both the physiological and molecular level. The results showed that PASP promoted biomass and nitrogen accumulation in maize seedlings, especially under low NO₃⁻ doses. Among different NO₃⁻ conditions, the most noticeable increase in plant biomass by PASP addition was observed in seedlings grown with 1 mmol L⁻¹ NO₃⁻, which was a little less than the optimum concentration (2 mmol L⁻¹) for plant growth. Furthermore, the total nitrogen accumulation increased greatly with additions of PASP to plants grown under suboptimal NO₃⁻ conditions. The promotion of nitrogen assimilation was mostly due to the increase of nitrate reductase (NR) activities. The NR activities in seedlings grown under low NO₃⁻ doses (0.5 and 1.0 mmol L⁻¹) were extremely increased by PASP, while the activities of glutamine synthetase (GS), aspartate aminotransferase (AspAT), and alanine aminotransferase (AlaAT) were slightly changed. Moreover, the regulation of PASP on NR activity was most probably due to the promotion of the protein accumulation rather than gene expression. Accumulation of NR protein was similarly affected as NR activity, which was markedly increased by PASP treatment. In conclusion, the present study provides insights into the promotion by PASP of nitrogen assimilation and identifies candidate regulatory enzymatic mechanisms, which warrant further investigation with the use of PASP in promoting nitrogen utilization in crops. Full article

Unmanned aerial vehicles (UAVs), as emerging plant protection machinery, have the advantages of high operational efficiency, high speed, and low drift. The current study aimed to elucidate the characteristics of droplet distribution and drift, control efficiency on cotton aphids and spider mites, and attachment and absorption of cotton leaves during UAV spraying. Kromekote card and filter paper are used as samplers to collect droplets, and the droplet density, coverage rate, deposition, and drift percentage are statistically analyzed. The pooled results showed that the droplet uniformity, the droplet coverage rate, the deposition, and the drifting ability are higher when the UAV flight height was 2 m. The control effects by UAV spraying on cotton aphids and spider mites were 63.7% and 61.3%, respectively. These values are slightly inferior to those obtained through boom spraying. Cotton leaf attachment and absorption of spirodiclofen after UAV spraying were slightly lower than those after boom spraying, therefore, the control efficiency of cotton pests is slightly different. According to the different flight height operations by the UAV sprayer, the drift capability of the droplets at 2 m flight height was large, and the droplet uniformity and deposition were satisfactory. The research results could provide the theoretical basis and technical support for UAV operation. Full article

Gossypium hirsutum L. is a worldwide economical crop; however, premature leaf senescence reduces its production and quality which is regulated by stresses, hormones, and genes. DNA binding with the one zinc finger (Dof) transcription factors (TFs) participate widely in plant development and responses to biotic and abiotic stresses, but there have been few reports of these TFs in cotton. Here, we perform a genome-wide study of G. Hirsutum L. Dof (GhDof) genes and analyze their phylogeny, duplication, and expression. In total, 114 GhDof genes have been identified and classified into nine subgroups (A, B1, B2.2, B2.1, C1, C2.1, C2.2, D1, and D2) based on phylogenetic analysis. An MCScanX analysis showed that the GhDof genes expanded due to segmental duplications. Quantitative real-time polymerase chain reaction (qRT-PCR) analysis showed that GhDofD9.6 was not only differentially expressed between CCRI10 (with premature senescence) and Liao4086 (without premature senescence) but also responded to salinity stress; GhDofA5.7, GhDofA7.4, GhDofA8.2, GhDof11.1, GhDofD7.2, and GhDofD11.3 signfificantly responded to cold (4 °C) stress. This work lays the foundation for further analysis of the function of GhDof genes in G. hirsutum, which will be helpful for improving the production and quality of cotton. Full article

This experiment was carried out in a greenhouse to evaluate the effects of selenium application (as Na₂SeO₃) on mineral concentration (as N, P, K, Ca and Se), biomass, yield and total antioxidant status (TAS) of tomato fruit. The study consisted of two experiments: an irrigation experiment with the application of selenium at 0, 2.5 and 5 mg L⁻¹ on the fertilizer solution in soil and perlite; and the foliar application experiment with selenium application at 0, 10, and 20 mg L⁻¹ in foliar spray every 20 days. Results showed that mineral content (as K, Ca, Mg and P) was not modified by selenium application. However, N decreased due to the Se applied in fertilizer solution 5 mg L⁻¹, and a negative correlation was found between the selenium applied in foliar form and the nitrogen concentration. The Se concentration, TAS, and biomass increased in plants in all Se treatments. However, the best response in TAS and Se in fruits was observed with foliar spray every 20 days at concentrations of 10 mg L⁻¹, without negative responses in biomass or mineral content. Full article

Jerusalem artichoke tubers have diverse applications in the food industry as well as in biotechnology. Their suitability depends mostly on the inulin content. Seasonal fluctuations of fructan exohydrolase activity responsible for inulin degradation was investigated in the tubers of three Jerusalem artichoke cultivars. The changes of fructan exohydrolase activity positively correlated with the changes of the content of total and short fructooligosaccharides. Therefore, to extract inulin with higher degree of polymerization for biotechnological purposes, the tubers of Jerusalem artichoke should be uprooted in autumn before the level of fructan exohydrolase reaches its maximum. If short fructooligosaccharides are desirable, the tubers in late autumn or spring tubers overwintered in soil are suitable. Full article

Vermicompost is the product of composting or breaking down organic matter through the use of earthworms. It is rich in essential plant nutrients, and has the ability to enhance the condition and increase the quality of the soil. In the present study, a field trial was conducted from January 2015 until March 2016 to elucidate the effects of vermicompost application (compared to supplementation with chemical fertilizer and no fertilizer) on the sandy loam soil and plant nutrients of pineapple (Ananas comosus var. MD2). The morphophysiology and yield performance of MD2 pineapple grown with vermicompost in the field were also evaluated. In this study, vermicompost was applied onto the sandy loam soils during transplanting, followed by a second application at seven MAP (months after planting) at the rate of 10 t ha⁻¹. On the other hand, the chemical fertilizer was applied based on the normal conventional cultivation practice. The soil and D-leaf samples at six MAP (S1) and during the red bud stage (S2; 10 MAP) were used to determine the soil and plant nutrient contents. The morphology of the plants was evaluated every month, and the fruits that were produced were subjected to quality analysis. Data analysis revealed that soil pH was increased after a second supplementation of vermicompost and contained significantly higher total N (0.15%) in the soils compared to the control (0.07%). There was no significant difference between plants supplied with chemical fertilizer and vermicompost in terms of plant height, number of leaves, or the length and width of D-leaves. However, different fertilization treatments were found to affect the yield and physical characteristics of the resulting fruits. Plants supplied with chemical fertilizer produced the highest fruit yield (136.97 t ha⁻¹) with the largest fruit size, followed by vermicompost (121.39 t ha⁻¹) and the control (94.93 t ha⁻¹). However, fruits supplied with vermicompost were observed to have the smallest crowns. Taken together, these results indicated that the use of vermicompost produced pineapple plants with excellent growth performance, comparable to that obtained when chemical fertilizer was used. Also, based on the cost analysis conducted, it was shown that the total cost (fertilizer and labor) for plants grown with vermicompost was lower than plants grown with chemical fertilizer. However, the usage of vermicompost as the single source of nutrients is not suggested for this type of soil and field conditions, but can be used as a supplement to maintain the soil quality and ensure agricultural sustainability. Full article

Natural rubber (NR) is currently sourced from a single species Hevea brasiliensis, which is primarily grown in Southeast Asia and Africa. The Taraxacum kok-saghyz (L.E. Rodin) (TK) plant, which grows in temperate climates and has NR in its roots, has been identified as an additional source for NR in the future. A major challenge to TK becoming a crop is direct seeding. This paper presents research on determining strategies for improving establishment of TK through direct seeding. Field trials were conducted in 2014 and 2015 in Ohio on a Wooster silt loam soil (2.4–2.9% OM) using “wild” TK seed. The study evaluated the impacts of different planting dates (April and May), planter types (broadcasting raw seed and drilling pelleted seed), companion crops, and compost mulch strips on plant stands (i.e., visible TK plant/TK seed drop). Results indicated that drilling of pelleted seed to a depth of 0.6 cm into a thin layer (<1.27 cm) of compost mulch after soil temperatures reach 16 °C (mid-May in Northern Ohio) would give the highest stand by the fall harvest season. These studies provide insight into direct seeding of TK and a baseline to use for evaluating future generations of TK. Full article

The present study aimed to characterize the simple sequence repeat markers in cotton using the cotton expressed sequence tags. A total of 111 EST-SSR polymorphic molecular markers with trinucleotide motifs were used to evaluate the 79 accessions of Gossypium L., (G. darwinii, 59 and G. barbadense, 20) collected from the Galapagos Islands. The allele number ranged from one to seven, with an average value of 2.85 alleles per locus, while polymorphism information content values varied from 0.008 to 0.995, with an average of 0.520. The discrimination power ranks high for the majority of the SSRs, with an average value of 0.98. Among 111 pairs of EST-SSRs and gSSRs, a total of 49 markers, comprising nine DPLs, one each of MonCGR, MUCS0064, and NAU1028, and 37 SWUs (D-genome), were found to be the best matched hits, similar to the 155 genes identified by BLASTx in the reference genome of G. barbadense, G. arboreum L., and G. raimondii Ulbr. Related genes GOBAR_DD21902, GOBAR_DD15579, GOBAR_DD27526, and GOBAR_AA04676 revealed highly significant expression 10, 15, 18, 21, and 28 days post-anthesis of fiber development. The identified EST-SSR and gSSR markers can be effectively used for mapping functional genes of segregating cotton populations, QTL identification, and marker-assisted selection in cotton breeding programs. Full article

In plants, transposable elements (TEs) represent a large fraction of the genome, with potential to alter gene expression and produce genomic rearrangements. Epigenetic control of TEs is often used to stop unrestricted movement of TEs that would result in detrimental effects due to insertion in essential genes. The current review focuses on the effects of methylation on TEs and their genomic context, and how this type of epigenetic control affects plant adaptability when plants are faced with different stresses and changes. TEs mobilize in response to stress elicitors, including biotic and abiotic cues, but also developmental transitions and ‘genome shock’ events like polyploidization. These events transitionally lift TE repression, allowing TEs to move to new genomic locations. When TEs fall close to genes, silencing through methylation can spread to nearby genes, resulting in lower gene expression. The presence of TEs in gene promoter regions can also confer stress inducibility modulated through alternative methylation and demethylation of the TE. Bursts of transposition triggered by events of genomic shock can increase genome size and account for differences seen during polyploidization or species divergence. Finally, TEs have evolved several mechanisms to suppress their own repression, including the use of microRNAs to control genes that promote methylation. The interplay between silencing, transient TE activation, and purifying selection allows the genome to use TEs as a reservoir of potential beneficial modifications but also keeps TEs under control to stop uncontrolled detrimental transposition. Full article

Onions (Allium cepa L.) are a medicinally and economically important vegetable species rich in sulphur compounds, polyphenols, and antioxidants. In Korea, most of the onion cultivars are of the open-pollinated, heterozygous, short duration, and early spring type, which are generally harvested in April. Precise varietal identification is crucially important to warrant the authenticity of supreme onion genotypes, which aid in affirming the genetic identity of breeding materials at both the breeders and farmers levels. A set of markers identified from the double-digest restriction-site associated DNA sequencing (ddRAD-seq) database of Allium cepa L. and involving single nucleotide polymorphisms (SNPs) were deployed for genotyping deoxyribonucleic acid (DNA) samples extracted from seven genetically diverse onion cultivars collected in Korea and Japan. The validation process led us to designating 43 SNPs out of 48 that unequivocally identified all seven genotypes with high statistical validity (p < 0.001). Phylogenetic relationships and varietal identity among the cultivars were ascertained by Bayesian clustering and ordination analyses. Two genotypes, Singsingball and Taegeukhwang of Korean origin, showed a greater genetic distance from the five other onion cultivars. The SNP markers deployed in this study effectively authenticated the DNA fingerprints of the early spring onion cultivars utilizing a high-throughput genotyping protocol. The method exploited in this study provides an efficient pathway of verifying genetic identity of onion genotypes for their quality control. The markers developed are highly useful in the management and conservation of elite onion breeding materials at the farmers’ level. Full article

Thousand kernel weight (TKW) is an important parameter for the evaluation of grain yield. The traditional measurement method relies on manual steps: weighing and counting. In this paper, we developed a system for the automated evaluation of thousand kernel weight that combines a weighing module and Android devices, called “gainTKW”. The system is able to collect the weight information from the weighing module through a serial port using the RS232-micro USB cable. In the imaging process, we adopt a k-means clustering segmentation algorithm to solve the problem of uneven lighting. We used the marker-controlled watershed algorithm and area threshold method to count the number of kernels that are touching one another. These algorithms were implemented based on the OpenCV (Open Source Computer Vision) libraries. The system tested kernel images of six species taken with the Android device under different lighting conditions. The algorithms in this study can solve the segmentation problems caused by shadows, as well. The appropriate numbers of kernels, of different species, are counted with an error ratio upper limit of 3%. The application is convenient and easy to operate. For the experiments, we can prove the efficiency and accuracy of the developed system by comparing the results between the manual method and the proposed application. Full article

Low forage quality of available perennial warm-season grasses during mid-summer through late summer affects the production of stocker cattle in the U.S. Southern Great Plains (SGP). Finger millet (Eleusine coracana Gaertn L.), which is a drought tolerant annual grass, could be a promising forage for the SGP. This field study assessed the adaptability and forage characteristics of 11 finger millet accessions originally sourced (1964–1981) from different parts of the world. Results of this study suggested that finger millet can generate forage yields ranging from 5.0 to 12.3 Mg ha⁻¹ 165 days after planting. Finger millet forage contained 105 to 156 g kg⁻¹ crude protein, 598 to 734 g kg⁻¹ neutral detergent fiber, 268 to 382 g kg⁻¹ acid detergent fiber, 597 to 730 g kg⁻¹ in vitro true digestibility, and 387 to 552 g kg⁻¹ neutral detergent fiber digestibility. Ten of the 11 accessions flowered and produced grains with yields varying from 60 to 1636 kg ha⁻¹. Overall, finger millet has the potential to serve as an alternative crop for the production of forage and possibly grain in the SGP. Further research needs to be focused on developing strategies for agronomic management and evaluating the capacity of finger millet under different grazing and hay production settings in the SGP. Full article

The purpose of this study was to demonstrate interest in applying simple and multiple logistic regression analyses to the marketability probability of commercial tomato (Solanum lycopersicum L.) cultivars when the tomatoes are harvested as loose fruit. A fruit’s firmness and commercial quality (softening or over-ripe fruit, cracking, cold damage, and rotting) were determined at 0, 7, 14, and 21 days of storage. The storage test simulated typical conditions from harvest to purchase-consumption by the consumer. The combined simple and multiple analyses of the primary continuous and categorical variables with the greatest influence on the commercial quality of postharvest fruit allowed for a more detailed understanding of the behavior of different tomato cultivars and identified the cultivars with greater marketability probability. The odds ratios allowed us to determine the increase or decrease in the marketability probability when we substituted one cultivar with a reference one. Thus, for example, the marketability probability was approximately 2.59 times greater for ‘Santyplum’ than for ‘Angelle’. Overall, of the studied cultivars, ‘Santyplum’, followed by ‘Dolchettini’, showed greater marketability probability than ‘Angelle’ and ‘Genio’. In conclusion, the logistic regression model is useful for studying and identifying tomato cultivars with good postharvest marketability characteristics. Full article

Saline stress severely affects the growth and productivity of plants. The activation of hormonal signaling cascades and reactive oxygen species (ROS) in response to salt stress are important for cellular detoxification. Jasmonic acid (JA) and the enzyme SOD (superoxide dismutase), are well recognized markers of salt stress in plants. In this study, the application of chitosan-polyvinyl alcohol hydrogels (Cs-PVA) and copper nanoparticles (Cu NPs) on the growth and expression of defense genes in tomato plants under salt stress was evaluated. Our results demonstrate that Cs-PVA and Cs-PVA + Cu NPs enhance plant growth and also promote the expression of JA and SOD genes in tomato (Solanum lycopersicum L.), under salt stress. We propose that Cs-PVA and Cs-PVA + Cu NPs mitigate saline stress through the regulation of oxidative and ionic stress. Full article

Blueberry (Vaccinium spp.) has been recognized worldwide as a valuable source of health-promoting compounds, becoming a crop with some of the fastest rising consumer demand trends. Fruit firmness is a key target for blueberry breeding as it directly affects fruit quality, consumer preference, transportability, shelf life, and the ability of cultivars to be machine harvested. Fruit softening naturally occurs during berry development, maturation, and postharvest ripening. However, some genotypes are better at retaining firmness than others, and some are crispy, which is a putatively extra-firmness phenotype that provides a distinct eating experience. In this review, we summarized important studies addressing the firmness trait in blueberry, focusing on physiological and molecular changes affecting this trait at the onset of ripening and also the genetic basis of firmness variation across individuals. New insights into these topics were also achieved by using previously available data and historical records from the blueberry breeding program at the University of Florida. The complex quantitative nature of firmness in an autopolyploid species such as blueberry imposes additional challenges for the implementation of molecular techniques in breeding. However, we highlighted some recent genomics-based studies and the potential of a QTL (Quantitative Trait Locus) mapping analysis and genome editing protocols such as CRISPR/Cas9 to further assist and accelerate the breeding process for this important trait. Full article

Adenophora triphylla (Thunb.) A.DC., three-leaf lady bell, is an important medicinal plant used against cancers and obesity. It has been well-established that the temperature regime affects plant growth and development in many ways. However, there is no study available correlating the growth of A. triphylla seedlings with different day and night temperature regimes. In order to find an optimal temperature regime, growth and physiology were investigated in A. triphylla plug seedlings grown in environment-controlled chambers at different day and night temperatures: 20/20 °C (day/night) (TA), 25/15 °C (TB), and 20/15 °C (TC). The seedlings in plug trays were grown under a light intensity of 150 μmol·m⁻²·s⁻¹ PPFD (photosynthetic photon flux density) provided by white LEDs, a 70% relative humidity, and a 16 h (day)/8 h (night) photoperiod for six weeks. The results showed that the stem diameter, number of roots, and biomass were significantly larger for seedlings in TB than those in TA or TC. Moreover, the contents of total flavonoid, total phenol, and soluble sugar in seedlings grown in TB were markedly higher than those in seedlings in the other two treatments. Soluble protein content was the lowest in seedlings in TC, while starch content was the lowest in seedlings grown in TA. Furthermore, seedlings grown in TB showed significantly lower activities of antioxidant enzymes such as superoxide dismutase, catalase, ascorbate peroxidase, and guaiacol peroxidase. Native PAGE (polyacrylamide gel electrophoresis) analysis further proved low activities of antioxidant isozymes in TB treatment. Meanwhile, the lowest content of hydrogen peroxide was observed in seedlings grown in TB. In conclusion, the results suggested that the 25/15 °C (day/night) temperature regime is the most suitable for the growth and physiological development of A. triphylla seedlings. Full article

Monitoring and improving environmental stress in crops is vital for the sustainable development of agriculture and food security. Traditional experimental methods are costly and time-consuming, yet crop growth models focus mainly only on water and nutrient stresses. In this study, a new World Food Studies (WOFOST) model, WOFOST-ES, was developed by the addition of a general environmental stress factor (ES). To calibrate and validate WOFOST-ES, two-year micro-plot experiments and one-year field experiments with sunflower were conducted in the Hetao Irrigation District, China. The results of the micro-plot experiments indicated that the WOFOST model failed to simulate sunflower growth correctly but that the WOFOST-ES model was highly accurate in simulating both yield (R² = 0.99, root mean square error (RMSE) = 56 kg/ha) and leaf area index (LAI) (R² = 0.86, RMSE = 0.44). A statistical method for estimating ESs based on the dominant stress factor (salt at our study site) was also proposed as a supplemental tool for WOFOST-ES, and micro-plot and field experiments conducted in 2013 and 2017 both proved acceptable accuracy of the statistical method when using WOFOST-ES. Comparison between ESs and the water and salt stress factors of Feddes-type stress reduction functions indicated that ESs failed to reveal actual environmental stresses during the sunflower seeding stage but did reflect other environmental stresses in addition to water and salt during the bud, flowering, and maturity stages. Although the present WOFOST-ES model proved to be accurate, stable, and practical, future studies should be performed, focusing on the physical separation of ESs, their mechanistic quantification, and their evaluation at small time steps using more observations. Full article

Molybdenum (Mo) is required in enzymes involved in a number of different metabolic processes, and is crucial for the survival of plants and animals. The influence of nutrient solutions containing four levels of molybdenum (0, 0.5, 1.5, and 3.0 µmol/L) on growth, yield, and quality of lettuce, escarole, and curly endive grown in a hydroponic floating system was evaluated. Biometric, nutrient, and quality analyses were conducted to assess the response of each species to Mo. The results demonstrated that molybdenum is essential for harvesting marketable plants. Lettuce, escarole, and curly endive plants differed significantly in their response to molybdenum fertilization. The increase of Mo concentration in the nutrient solution was not harmful for plants and had no influence on yield and morphological traits of the leafy vegetables; however, it significantly affected some quality characteristics. Mo fertilization raised the nutritional quality by increasing ascorbic acid content up to 320.2, 139.0, and 102.1 mg kg⁻¹ FW (fresh weight), and reducing nitrate content down to 1039.2, 1047.3, and 1181.2 mg kg⁻¹ FW for lettuce, escarole, and curly endive, respectively. The addition of Mo in the nutrient solution increased the Mo content of plants up to 0.50, 4.02, and 2.68 μg g⁻¹ FW for lettuce, escarole, and curly endive, respectively. Increasing Mo supply to lettuce, escarole, and curly endive up to 3.0 µmol L⁻¹ could lead to a higher nutritional quality with no significant morphological alteration or yield loss. Full article

Stevia leaves, which are commonly used as a natural sweetener in food products, have increased in importance for antioxidant delivery due to their high content of phenolic compounds. In this study, the influence of the drying process on stevia leaves, with regards to phenolic content and antioxidant activity during drying kinetics 40 °C for 7 h, was studied. The effect of solvent concentration and extraction time using a 3² factorial design on total phenol content (TPC), and on antioxidant activity of extracts obtained from dried stevia leaves, by ultrasound assisted extraction (UAE) as alternative method was evaluated. Steviol glycosides contents were also evaluated by a conventional and UAE method. Phenols identification, quantification and purification were performed by Ultra Performance Liquid Chromatography-Electrospray Ionization-Mass Spectrometry (UPLC-ESI-MS), Ultra Performance Liquid Chromatography-Photodiode Array (UPLC-PDA) and advanced automated flash purification, respectively. Drying time affected the moisture content of stevia leaves. A constant weight was reached after six hours of drying, and higher antioxidant activity was observed, while the highest TPC was obtained after seven hours of drying. The highest TPC (91.57 ± 8.8 mg GAE/g dw) and antioxidant activity (603.24 ± 3.5 μmol TE/g dw) in UAE method was obtained when ethanol 50% at 5 min was used. Steviol glycosides extracted by UAE were recorded with a content of 93.18 ± 1.36 mg/g dw and 98.97 ± 1.75 mg/g dw for stevioside and rebaudioside A respectively. Six phenolic compounds including four phenolic acids and two flavonoids were identified and quantified by UPLC-PDA, and confirmed by ESI-MS reporting its fragmentation pattern. Diosmin and chlorogenic acid were the most abundant compounds with values of 2032.36 μg/mL and 434.95 μg/mL respectively. As a novelty we found that the antioxidant activity evaluated in partially purified fractions suggested that biological activity might be attributed to the synergistic effect of the six phenols present in the stevia leaves extract. In addition to its sweeting properties, stevia leaves constitute a potential source of polyphenolic compounds, with antioxidant activity that could be used as a food additive. Full article

The recommended sowing rate of alfalfa (Medicago sativa L.) is about 10 kg pure live seed ha⁻¹, but it is debated if increasing the sowing rate enhances forage yield and quality in the sowing year. This study was conducted to: (i) determine the optimal sowing rate to maximize forage yield; and (ii) determine the relationship between plant and stem density with forage yield and nutritive value. Experiments were conducted at three sites in North Dakota between 2013 and 2016. Six sowing rates [1, 5, 10, 15, 20, and 25 kg ha⁻¹ pure live seed (PLS)] were evaluated. Results indicated that total forage yield in the sowing year was lower only with the lowest sowing rate. Maximum total forage yield in the sowing, first, second, and third production years was obtained with 73, 52, 37, and 36 plants m⁻² and 575, 495, 435, and 427 stems m⁻², respectively. In the sowing and first production year, both plant and stem density predicted forage yield similarly. In older stands, stem density predicted forage yield slightly better. Forage nutritive value was similar among sowing rates indicating an increase in sowing rate does not enhance forage nutritive value. In conclusion, increasing the sowing rate above the recommended rate (10 kg PLS ha⁻¹) does not increase forage yield or quality. Full article

Water imbalance condition (WIC) in a maize-soybean relay intercropping system is the main abiotic stress limiting biomass production and seed yield and, consequently, seed-quality. This experiment was started to study the effects of WIC on soybean, in which two soybean genotypes ND12 and C103 were grown in pots with roots split equally between two soil column and six WIC treatments (%) T1 (100), T2, (100:50), T3 (100:20), T4 (50:50), T5 (50:20), and T6 (20:20) field capacity on both sides of soybean roots were used. Results showed that both genotypes responded significantly to WIC treatments for all the parameters; however, the level of response differed between genotypes. Maximum osmoprotectants (except proline), biomass, yield and yield-related traits and superior seed quality were observed with ND12. Among WIC treatments, T2 and T3 produced 94% and 85%, and 93% and 81% of T1 biomass and yield, respectively. Similarly, treatments T2 and T3 also improved the oil quality by maintaining the content of unsaturated fatty acids and isoflavone content, while opposite trends were observed for protein content. Overall, moderate water reduction (T2 and T3) can improve soybean seed-quality and by selecting drought-resistant genotypes we can increase the soybean yield under intercropping systems. Full article

Moringa oleifera Lam is a plant that has recently gained importance as a food because of its nutritional value and bioactive compound content and because practically all the organs are usable. The use of nanoparticles has appeared as an alternative to increase bioactive compounds in plants. The goal of this work was to determine if the application of copper nanoparticles would increase the content of bioactive compounds and antioxidant capacity in M. oleifera. Copper (Cu) nanoparticles were applied to the leaves at four different times throughout crop growth. The biocompounds were analyzed after the second, third, and fourth applications. The results show that application of Cu nanoparticles has a beneficial effect on the accumulation of bioactive compounds in M. oleifera leaves. In addition, the antioxidant capacity and carotenoid and chlorophyll contents in the leaves of M. oleifera increased after Cu nanoparticles application. The same effect was not observed in the fruit of M. oleifera. Here, the bioactive compound contents diminished. Therefore, the use of Cu nanoparticles can be an important alternative to improve the quality of this plant, particularly that of the leaves. Full article