Performance of Different Tomato Genotypes in the Arid Tropics of Sudan during the Summer Season. II. Generative Development

Eleven tomato genotypes of diverse origin were grown in Shambat, University of Khartoum, Sudan, in a randomized block design with three replications for two successive seasons (2002/2003, 2003/2004). The same genotypes were firstly evaluated under glasshouse conditions at the Humboldt University of Berlin, Germany during 2002. Highly significant differences were encountered among the different genotypes for most of the generative characters, such as number of days to flowering, number of flowers per plant, number of fruits per plant, fruit fresh weight per plant and fruit set percentage. Based on results obtained from this study, the genotype ‘Summerset’ proved to be high yielding under high temperature conditions in comparison to other genotypes

Does the Short Term Fluctuation of Mineral Element Concentrations in the Closed Hydroponic Experimental Facilities Affect the Mineral Concentrations in Cucumber Plants Exposed to Elevated CO\u3csub\u3e2\u3c/sub\u3e?

Aims Studies dealing with plants’ mineral nutrient status under elevated atmospheric CO2concentration (eCO2) are usually conducted in closed hydroponic systems, in which nutrient solutions are entirely renewed every several days. Here, we investigated the contribution of the fluctuation of concentrations of N ([N]), P ([P]), and K ([K]) in nutrient solutions in this short period on their concentrations in cucumber plants exposed to different [CO2] and N levels. Methods Cucumber (Cucumis sativus L.) plants were hydroponically grown under two [CO2] and three N levels. [N], [P], and [K] in nutrient solutions and cucumber plants were analyzed. Results The transpiration rate (Tr) was significantly inhibited by eCO2, whereas Tr per plant was increased due to the larger leaf area. Elevated [CO2] significantly decreased [N] in low N nutrient solutions, which imposed an additional decrease in [N] in plants. [P] in nutrient solutions fluctuated slightly, so the change of [P] in plants might be attributed to the dilution effect and the demand change under eCO2. [K] in moderate and high N nutrient solutions were significantly decreased, which exacerbated the [K] decrease in plants under eCO2. Conclusions The short-term fluctuation of [N] and [K] in nutrient solutions is caused by the asynchronous uptakes of N, K, and water under eCO2, which has an appreciable influence on [N] and [K] in plants besides the dilution effect. This defect of the closed hydroponic system may let us exaggerate the negative impact of eCO2 itself on [N] and [K] in plants

Performance of Different Tomato Genotypes in the Arid Tropics of Sudan during the Summer Season. I. Vegetative Growth

Selected, eleven tomato genotypes of diverse origin were grown in a glasshouse of the Humboldt University of Berlin, Germany during 2002 and under field conditions in Shambat, University of Khartoum, Sudan for two successive seasons (2002/2003, 2003/2004). High temperatures under field conditions resulted in poor stand and stunted growth of tomato plants. Highly significant differences were encountered among the different genotypes for leaf area, leaf area ratio, leaf weight ratio, stem fresh and dry weight and leaf fresh and dry weight. Based on results obtained from this study, the genotype ‘Summerset’ proved to be more tolerant under high temperature conditions in comparison to other investigated genotypes and may be useful for exploitation under arid tropical region of Sudan

Interactive Effects of the CO\u3csub\u3e2\u3c/sub\u3e Enrichment and Nitrogen Supply on the Biomass Accumulation, Gas Exchange Properties, and Mineral Elements Concentrations in Cucumber Plants at Different Growth Stages

The concentration changes of mineral elements in plants at different CO2 concentrations ([CO2]) and nitrogen (N) supplies and the mechanisms which control such changes are not clear. Hydroponic trials on cucumber plants with three [CO2] (400, 625, and 1200 µmol mol−1) and five N supply levels (2, 4, 7, 14, and 21 mmol L−1) were conducted. When plants were in high N supply, the increase in total biomass by elevated [CO2] was 51.7% and 70.1% at the seedling and initial fruiting stages, respectively. An increase in net photosynthetic rate (Pn) by more than 60%, a decrease in stomatal conductance (Gs) by 21.2–27.7%, and a decrease in transpiration rate (Tr) by 22.9–31.9% under elevated [CO2] were also observed. High N supplies could further improve the Pn and offset the decrease of Gs and Tr by elevated [CO2]. According to the mineral concentrations and the correlation results, we concluded the main factors affecting these changes. The dilution effect was the main factor driving the reduction of all mineral elements, whereas Tr also had a great impact on the decrease of [N], [K], [Ca], and [Mg] except [P]. In addition, the demand changes of N, Ca, and Mg influenced the corresponding element concentrations in cucumber plants

Is Soilless Culture a Sustainable Form of Agriculture?

A soilless culture system (SCS) is a technique used for plant production that has recently become increasingly popular [1,2]. For instance, almost all greenhouse areas in the Netherlands use SCSs due to their benefits, including up to 50% savings on water and fertilisers, the ability to steer crop growth vegetatively or generatively, and higher yields with better quality [3,4,5]. Similar systems with low investments can be used in mid- and low-tech horticulture. SCSs also enable growers to start with a disease-free crop; crop rotation is no longer required [5]. Further, it significantly benefits regions facing water scarcity, unfavourable soil conditions, infertility, soil-borne diseases, salinity, or sodicity [1,2,6]. Especially when water shortage is an issue, circulating surplus nutrient solutions can save water and expensive fertilisers. Alternatively, the surplus can be used in another crop without recirculating [4]. The primary goal is intensification. Thus, an SCS is employed in areas with suitable climate conditions and proximity to major urban centres to ensure and increase productivity

Drought tolerance and water status of bean plants (Phaseolus vulgaris L.) as affected by citric acid application

   Enhancement of drought tolerance of plants is a crucial concern in arid and semi-arid regions. Using safe and environmentally-friendly tools and treatments for this purpose is needed to overcome the problems of water shortage with particular emphasis on sustainable resource management and environmental protection. This study investigated the water status and drought tolerance of beans. Bean plants (Phaseoulus vulgaris L.) were treated with citric acid (0.5, 1, 1.5 and 2 g/L) as a foliar application prior the exposition to drought stress conditions. Physiological changes, such as leaf temperature, relative water content (RWC) and chlorophyll content of leaves, were recorded in response to citric acid application. The results revealed that the water status of bean plants under drought stress conditions was improved by citric acid application, indicated by higher RWC of leaves compared to control plants. The most effective level in this respect was 1.5 g/L. A similar trend was observed with total chlorophyll content of leaves. In addition, plant growth, productivity and quality parameters were significantly improved by application of citric acid compared to control plants. The possible roles of citric acid on water status and drought tolerance of bean plants are discussed

Energiekonzepte für den Gartenbau - Untersuchungen zu den Auswirkungen weiterer Heizölpreissteigerungen auf sächsische Gartenbauunternehmen, daraus abgeleitete innovative Handlungsfelder und Strategien

Untersuchungen zu den Auswirkungen weiterer Heizölpreissteigerungen auf sächsische Gartenbauunternehmen, daraus abgeleitete innovative Handlungsfelder und Strategie

Promising composts as growing media for the production of baby leaf lettuce in a floating system

The floating system is a successful strategy for producing baby leaf vegetables. Moreover, compost from agricultural and agri-food industry wastes is an alternative to peat that can be used as a component of growing media in this cultivation system. In this study, we experimented with three composts containing tomato (Solanum lycopersicum L.), leek (Allium porrum L.), grape (Vitis vinifera L.), and/or olive (Olea europaea L.) mill cake residues, which were used as the main component (75/25 volume/volume) of three growing media (GM1, GM2 and GM3) to evaluate their e_ect on the growth and quality of red baby leaf lettuce (Lactuca sativa L.). We used a commercial peat substrate as a control treatment (100% volume) and in mixtures (25% volume) with the composts. The plants were cultivated over two growing cycles, in spring and summer, and harvested twice in each cycle when the plants had four to five leaves. We found that the percentage of seed germination was significantly higher in plants grown in peat than in those grown in compost growing media. The yield was a_ected by the growing media in the summer cycle, and we obtained the highest value with GM1. Furthermore, the second cut was more productive than the first one for all the growing media in both cycles. The lettuce quality was also a_ected by the growing media. In general, the total phenolic content and antioxidant capacity in the leaves was higher in plants grown in the compost growing media, particularly in the second cut, but the nitrate content in the leaves was greater in some of the compost treatments compared with the peat treatment. In addition, an in vitro suppressive activity study demonstrated that the interaction between di_erent fungi and bacteria observed through metagenomics analysis could contribute to the e_ectiveness of the compost in controlling Pythium irregulare. The use of compost as a component of the growing media in the production of baby leaf vegetables in a floating system does not only favor the crop yield and producto quality, but also shows suppressive e_ects against P. irregulare.This research was funded by the Spanish Ministry of Economy and Competitiveness: Reference project: AGL2017-84085-C3-1-R, AGL2017-84085-C3-2-R, AGL2017-84085-C3-3-R

Enhancing the cultivation of Salicornia fruticosa with agroindustrial compost leachates in a cascade cropping system: evaluating the impact of melatonin application

Cascade cropping systems (CCS) utilize leachate from a primary crop to grow secondary crops and enhance the efficient use of water and fertilizers in areas with scarce water resources. A preliminary study investigated the effect of melatonin in a cascade cropping system to potentially improve plant tolerance to abiotic stresses. This study aimed to cultivate Salicornia fruticosa in this cropping system to reduce nutrient discharge and assess the impact of exogenous melatonin on Salicornia growth and quality. The CCS included a primary crop of Salicornia grown in an agro-industrial compost or peat. Leachates from these media were used to cultivate the same plant once again in a floating system under four treatments: compost leachate (T1), peat leachate (T2), 100% nutrient solution (NS) (T3), 50% NS (T4) strength. Four concentrations of exogenous melatonin were applied in foliar spray: 0, 100, 200, and 400 µM. Melatonin application increased yield, with the highest values observed when plants were grown in T1. Water use efficiency was also maximized in T1 and with both 200 and 400 µM melatonin applications. The highest nitrogen use efficiency was achieved in plants grown in peat leachate. The lipid membrane damage was assessed revealing that plants grown in compost leachate exhibited the lowest MDA values regardless of melatonin concentrations. The accumulation of some antinutritional compounds (nitrate, oxalate, and sodium) were the highest in those plants grown in compost leachate. Overall, shoots grown in peat leachate exhibited the best phytochemical profile (total phenol content, total flavonoids, and antioxidant capacity), with peak values in plants treated with 200 µM melatonin. These findings suggest that S. fruticosa can be effectively cultivated using leachate from a previous crop in a floating system and that exogenous melatonin application enhances the yield and nutritional quality of Salicornia shoots.The author(s) declare financial support was received for the research, authorship, and/or publication of this article. The research was supported by Grant PID2020-114410RB-I00 funded by MCIN/AEI/10.13039/501100011033 and Grant AGROALNEXT funded by Comunidad Autónoma de la Región de Murcia through Fundación Séneca—Agencia de Ciencia y Tecnologı́a de la Región de Murcia and European Union NextGenerationEU

Do soilless culture systems have an influence on product quality of vegetables?

In the horticulture industry, the focus has traditionally been on yield. However, consumers’ interest worldwide in the quality of horticultural products has increased in the recent past and will become the driving force in the future. Soilless culture systems (SCSs), the most intensive production method in today’s horticulture industry, are based on environmentally friendly technology, which can result in higher yields, even in areas with adverse growing conditions. However, using SCSs does not automatically result in the production of high-quality vegetables. Numerous studies confirm that a SCS enables growers to produce vegetables without quality losses compared to soil cultivation. An adaptation of cultural management to the specific cultural system, as well as crop demand, can further result in the improvement of the quality of horticultural products.Peer Reviewe