Deficit irrigation influences yield and lycopene content of diploid and triploid watermelon

Many vegetable production regions in the southwestern US are strictly regulated on water use. In addition, demand for high quality and nutritious vegetables has increased. This study was performed to explore the effects of deficit irrigation on yield, fruit quality and lycopene content of red-fleshed diploid and triploid watermelon (Citrullus lanatus (Thunb) Matsum & Nakai) cultivars. Irrigation treatments were 1.0, 0.75 and 0.5 evapotranspiration (ET) rates. Cultivars used were ‘Summer Flavor 710’, ‘RWW 8036’, ‘Allsweet’, ‘Sugarlee’, and ‘SWD 7302’ (diploids) and ‘Summer Sweet 5244’, ‘SWT 8706’, ‘Sugar Time’, and ‘Tri-XSunrise’ (triploids). Total water applied through a subsurface drip system was 395, 298 and 173 mm, for the 1.0, 0.75 and 0.50 ET, respectively. Total yields were highest at 1.0 ET (53.9 t ha-1) compared with 0.5 ET (26.8 t ha-1). Triploids had a 34% higher total yield and fewer culls (2%) compared with diploid cultivars (25%). Highest yields were obtained for ‘Sunrise’, ‘SWT 8706’, and ‘SWD 7302’. Highest soluble solid content was measured for ‘Sugar Time’ (13.4%) and was significantly higher than other cultivars (range 9.7-11.0 %). Triploid cultivars had more firm flesh, compared with diploids (12.0 vs. 9.9 N). Lycopene content increased slightly with maturity (55.8 to 60.2 :g g-1 fw), and was significantly higher at 0.75 ET than 1.0 ET in melons at ripe and overripe maturity stages. Lycopene content averaged over all treatments was 60-66 :g g-1 fw for triploids and 45 to 80 μg g-1 fw for diploid fruit.The authors thank the Texas Department of Agriculture and USDA for their partial financial support, to Sakata, Novartis, Abbott & Cobb, Willwhite, and Sugar Creek Seeds for providing seeds, and to Tropical Star for growing the transplants

USCID fifth international conference

Presented at the fifth international conference on irrigation and drainage, Irrigation and drainage for food, energy and the environment on November 3-6, 2009 in Salt Lake City, Utah.Includes bibliographical references.The urban water demand in Southwest Texas has grown rapidly in recent years due to large population increase. Regulated deficit irrigation (RDI) is one important measure for saving water while maintaining crop yield/ net benefit. An RDI field experiment was conducted at the Texas AgriLIFE Research and Extension Center at Uvalde in the summer of 2008 to examine the water saving potential. Seven irrigation schemes and four varieties were assigned to the experimental field to test their effects on lint yield. The results showed that: 1) The threshold of the replacement ratio is between 0.7 and 0.8 in fixed ratio irrigation schemes. Dynamic irrigation schemes showed a higher potential to save irrigation water. 2) The fiber quality was affected more by varieties than by irrigation schemes. A 50X (fixed 50% ratio) scheme has the potential risk to produce relatively lower quality cotton fiber by affecting fiber length and fiber yellowness. Considering its negative effect on lint yield as well, the 50X scheme is definitely not recommended. The two dynamic irrigation schemes, 50D and 70D, showed no negative effect on fiber quality. The 70D scheme has some potential to increase the fiber quality in fiber length, uniformity, fiber strength and reflectance; however, this scheme uses more irrigation water that the 50D scheme. Although further research is needed before making definitive conclusions, both dynamic schemes could be applied to maintain lint yield and fiber quality while saving more water, compared to the fixed ratio irrigation schemes

Assessing Tomato Genotypes for Organic Hydroponic Production in Stressful Environmental Conditions

Identifying tomato genotypes that can thrive and produce abundantly under arid climatic conditions and addressing the growing food demand caused by population growth are pressing concerns for food security. This research aimed to assess the growth, physiological, phenological, fruit yield, and postharvest quality of tomato genotypes cultivated in an organic hydroponic system in Qatar, where abiotic stress conditions prevail. Ten different tomato genotypes were carefully evaluated, and comprehensive data regarding their growth and development were collected and analyzed. The performance of these tomato genotypes across all traits related to yield and quality showed significant variations. Notably, the ‘Velocity’ and ‘Sigma’ genotypes consistently exhibited robust vegetative growth and improved phenological characteristics compared with the other tomato cultivars. Specifically, ‘Velocity’ and ‘Sigma’ displayed increased leaf assimilation rates (35% and 32%), stomatal conductance (14% and 11%), and reduced transpiration loss (50% and 44%) compared with ‘SV4129TH’. These genotypes also showed lower electrolyte leakage (32% and 28%) and maintained higher intercellular CO2 concentrations. Furthermore, ‘Velocity’ exhibited an accelerated flowering pattern, with the first flowering occurring 4 days sooner and 50% flowering occurring 5 days sooner than that of ‘SV4129TH’. ‘Velocity’ also demonstrated superior fruit set (14%), pollen viability (24%), and fewer incidences of flower drops (36%) compared with ‘SV4129TH’. Notably, ‘Velocity’ outperformed ‘SV4129TH’ in terms of marketable fruit yields, with a 32% higher yield. In addition to its impressive yield, ‘Velocity’ exhibited superior postharvest quality, including firmness, Brix level, acidity, and color. Therefore, overall, ‘Velocity’ and ‘Sigma’ emerged as promising genotypes with strong abiotic stress tolerance capabilities. The correlation analysis of these traits provided valuable insights into the selection and breeding of genotypes that can withstand abiotic stress conditions, laying the foundation for effective comparisons and selections of genotypes suitable for organic hydroponic cultivation in stressful environments

Comparison of direct-seeded, bareroot, and various tray seedling densities on growth dynamics and yield of long-day onion

– Root, bulb and shoot growth of transplanted onions produced from seedlings on 228-cell flats were determined. Treatments were one (TC1), two (TC2) or three (TC3) seedlings/cell, and single plants separated at transplanting from those grown with two (TC2-1) or three (TC3-1) seedlings/cell. Controls were direct seeding (DS) and bareroot transplants (BR). Transplants were established with the following in-row spacings: 5 cm (BR, TC1, TC2-1 and TC3-1), 10 cm (TC2) and 15 cm (TC3). During early to mid-development root number and root dry weight were higher for TC1 as compared with BR. Transplant leaf mass peaked between 64 and 80 days after transplanting (DAT). Initially, DS had a rapid bulbing rate, while transplants exhibited a faster rate 60 DAT. Before final maturity, TC1 had a higher bulb size than DS and TC3. Total yields were similar, but yields by size class differed significantly between treatments. DS and TC3 had an increase in the small bulb size (35–50 mm diameter). All containerized transplants, except for TC3, had an increase in the large bulb size (60–70 mm). TC1 had 36% of the total marketable yield in the jumbo size (> 70 mm) compared with 16% for direct seeding and 24% for bareroot transplants.– Comparaison entre le semis direct, la transplantation à racine nue et diverses densités de plants en godets dans la dynamique du développement et la production d’oignon de jour long. Développement d’oignon transplanté à densité augmentée. Le développement de la racine, du bulbe et du tige d’oignon transplanté obtenu à partir de plants en godets de 228 compartiments a été étudié. Les traitements ont été un (TC1), deux (TC2), ou trois (TC3) plants/compartiment, et une plante séparée dans la transplantation de celles développées avec deux (TC2-1) ou trois (TC3-1) plants/compartiment. Les contrôles ont été : semis direct (DC) et transplantation à racine nue (BR). Les plantes transplantées ont été disposées en rangée avec les distances suivantes : 5 cm (BR, TC1, TC2-1, TC3-1), 10 cm (TC2), et 15 cm (TC3). Pendant le premier et le mi-développement le nombre de racines et le poids sec de racines a été supérieur pour TC1 comparé avec BR. La masse de feuilles des plantes transplantées s’est desséchée dans les 64 et les 80 jours après la transplantation (DAT). Initialement, DS a eu un taux de formation de bulbe rapide, tandis que les plantes transplantées ont montré un taux plus rapide 60 DAT. Avant la maturité finale, TC1 a eu une taille des bulbes plus grande que DS et TC3. Les productions totales ont été semblables, mais la production en classes de taille a différé de manière significative entre les traitements. DS et TC3 ont eu une augmentation dans la taille des bulbes petits (35–50 mm de diamètre). Tous les plants en godet, excepté TC3, ont eu une augmentation significative dans la taille des bulbes grands (60–70 mm). TC1 a eu 36% de la production totale commercialisable avec la taille jumbo (> 70 mm) par rapport à 16% pour le semis direct et à 24% pour la transplantation à racine nue

Stable population structure in Europe since the Iron Age, despite high mobility

Ancient DNA research in the past decade has revealed that European population structure changed dramatically in the prehistoric period (14,000–3000 years before present, YBP), reflecting the widespread introduction of Neolithic farmer and Bronze Age Steppe ancestries. However, little is known about how population structure changed from the historical period onward (3000 YBP - present). To address this, we collected whole genomes from 204 individuals from Europe and the Mediterranean, many of which are the first historical period genomes from their region (e.g. Armenia and France). We found that most regions show remarkable inter-individual heterogeneity. At least 7% of historical individuals carry ancestry uncommon in the region where they were sampled, some indicating cross-Mediterranean contacts. Despite this high level of mobility, overall population structure across western Eurasia is relatively stable through the historical period up to the present, mirroring geography. We show that, under standard population genetics models with local panmixia, the observed level of dispersal would lead to a collapse of population structure. Persistent population structure thus suggests a lower effective migration rate than indicated by the observed dispersal. We hypothesize that this phenomenon can be explained by extensive transient dispersal arising from drastically improved transportation networks and the Roman Empire’s mobilization of people for trade, labor, and military. This work highlights the utility of ancient DNA in elucidating finer scale human population dynamics in recent history

Direct Seeding and Transplanting Influence Root Dynamics, Morpho-Physiology, Yield, and Head Quality of Globe Artichoke

The objective of this two-year field study was to assess the influence of stand establishment methods (direct seeding or transplanting) on root growth dynamics, shoot morphology, leaf physiology, yield, and quality of globe artichoke (Cynara cardunculus). Three artichoke cultivars were evaluated, ‘Green Globe Improved’ (GGI), ‘Imperial Star’ (IS), and ‘Romolo’ (ROM). Plants established with the transplanting method had higher mean root length intensity (La), root length, and root surface area as compared to plants established by direct seeding. The topsoil (0–20 cm) had on average higher La, root length, and root surface area than deeper soil profiles. Transplanted plants had higher plant shoot width and leaf area index (LAI) chlorophyll content index (SPAD) than direct seeded plants at the vegetative stage in 2015. The improvement of root and shoot growth in transplants (compared to direct seeding) also resulted in higher (p < 0.05) marketable yield (21.1 vs. 19.9 ton ha−1 in 2015 and 18.3 vs. 13.7 ton ha−1 in 2016). Additionally, 46–50% of the total yield occurred during the first 30 days of harvest in the transplanting method compared to 13–38% for direct seeding. No significant differences were found between planting methods or cultivars in leaf-level gas exchange (photosynthesis, stomatal conductance, and transpiration) and cynarin concentration in the marketable heads. Although chlorogenic acid was similar in both establishment methods in 2015, direct seeding had higher concentration in 2016. Comparing cultivars, GGI had higher root length, surface area, root volume, and earlier and higher marketable yield than ROM. However, ROM had higher mean root length intensity (La; total root length per specific area in soil profile) than GGI in both growing seasons. This study showed significant and consistent improvements in root and shoot traits, and yield for transplants as compared to direct seeded plants

Exploring Morpho-Physiological Variation for Heat Stress Tolerance in Tomato

Texas tomato production is vulnerable to extreme heat in the spring-summer cropping period, which is exacerbated by the lack of superior genetic materials that can perform well in such environments. There is a dire need for selecting superior varieties that can adapt to warm environments and exhibit high yield stability under heat stress conditions. This research aimed at identifying heat-tolerant varieties under heat-stress conditions in controlled and open-field environments and was carried out in three stages. For the first experiment, 43 varieties were screened based on yield responses in natural open-field environment. From those, 18 varieties were chosen and exposed to control (greenhouse: 26/20 °C) and constant heat-stress (growth-chamber: 34/24 °C) conditions for three months. Measurements were done for chlorophyll fluorescence, chlorophyll content (SPAD), plant height, stem diameter and heat injury index (HII). The last experiment was conducted in an open field with a pool of varieties selected from the first and second experiments. Leaf gas exchange, leaf temperature, chlorophyll fluorescence, SPAD value, electrolyte leakage, heat injury index and yield were assessed. From the combined studies, we concluded that heat-tolerant genotypes selected by using chlorophyll fluorescence and HII in controlled heat-stress conditions also exhibited heat-tolerance in open-field environments. Electrolyte leakage and HII best distinguished tomato varieties in open-field environments as plants with low electrolyte leakage and HII had higher total yield. \u27Heat Master,\u27 \u27New Girl,\u27 \u27HM-1823,\u27 \u27Rally,\u27 \u27Valley Girl,\u27 \u27Celebrity,\u27 and \u27Tribeca\u27 were identified as high heat-tolerant varieties. Through trait correlation analysis we provide a better understanding of which traits could be useful for screening and breeding other heat-tolerant tomato varieties

Ethylene regulators influence germination and root growth of globe artichoke seedlings exposed to heat stress conditions

High seed germination and root vigour are important traits to improve post-transplant performance of artichoke (Cynara cardunculus var. scolymus) under heat stress conditions. The effects of exogenous applications of five ethylene regulators each at different concentrations were evaluated on germination and early root growth of artichoke at 23°C in two incubation assays. The ethylene precursors or promoters were DL-methionine (DL-MET), 1-aminocyclopropane-l-carboxylic acid (ACC) and 2-chloroethylphosphonic acid (ethephon, ETH); and ethylene inhibitors were aminoethoxyvinylglycine (AVG) and 1-methylcyclopropene (1-MCP). A subsequent study examined the effects of ETH concentrations on seeds exposed at 23 vs. 30°C (stress). Seed thermodormancy was significantly improved by the application of 30 μM L-1 ETH. At optimal temperature (23°C), early root growth was enhanced by ACC and ETH (range of 1-100 μM L-1) with increasing root hair density, root area and lateral roots (except with ETH at 30 μM L-1). Conversely, AVG induced primary root elongation but decreased root hair formation. At higher temperature (30°C), inhibition of early root growth was alleviated when seedlings were incubated at 30 μM L-1 ETH. Our results suggest that exogenous ethylene could be useful to alleviate heat stress on artichoke seeds and seedlings, which in turn may improve early growth during stand establishment.Fil: Shinohara, T.. Sanyu Consultants Inc.; JapónFil: Martin, Eugenia Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Investigaciones en Ciencias Agrarias de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Agrarias. Instituto de Investigaciones en Ciencias Agrarias de Rosario; ArgentinaFil: Leskovar, Daniel Ivan. Texas A&M University; Estados Unido

Effect of Irrigation Timing on Root Zone Soil Temperature, Root Growth and Grain Yield and Chemical Composition in Corn

High air temperatures during the crop growing season can reduce harvestable yields in major agronomic crops worldwide. Repeated and prolonged high night air temperature stress may compromise plant growth and yield. Crop varieties with improved heat tolerance traits as well as crop management strategies at the farm scale are thus needed for climate change mitigation. Crop yield is especially sensitive to night-time warming trends. Current studies are mostly directed to the elevated night-time air temperature and its impact on crop growth and yield, but less attention is given to the understanding of night-time soil temperature management. Delivering irrigation water through drip early evening may reduce soil temperature and thus improve plant growth. In addition, corn growers typically use high-stature varieties that inevitably incur excessive respiratory carbon loss from roots and transpiration water loss under high night temperature conditions. The main objective of this study was to see if root-zone soil temperature can be reduced through drip irrigation applied at night-time, vs. daytime, using three corn hybrids of different above-ground architecture in Uvalde, TX where day and night temperatures during corn growing season are above U.S. averages. The experiment was conducted in 2014. Our results suggested that delivering well-water at night-time through drip irrigation reduced root-zone soil temperature by 0.6 °C, increase root length five folds, plant height 2%, and marginally increased grain yield by 10%. However, irrigation timing did not significantly affect leaf chlorophyll level and kernel crude protein, phosphorous, fat and starch concentrations. Different from our hypothesis, the shorter, more compact corn hybrid did not exhibit a higher yield and growth as compared with taller hybrids. As adjusting irrigation timing would not incur an extra cost for farmers, the finding reported here had immediate practical implications for farm scale adaptation to hot environments