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Horticulturae, Volume 3, Issue 3 (September 2017)

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Research

Open AccessArticle Growth and Tissue Elemental Composition Response of Butterhead Lettuce (Lactuca sativa, cv. Flandria) to Hydroponic Conditions at Different pH and Alkalinity
Horticulturae 2017, 3(3), 41; doi:10.3390/horticulturae3030041
Received: 28 April 2017 / Accepted: 29 June 2017 / Published: 13 July 2017
Cited by 2 | PDF Full-text (431 KB) | HTML Full-text | XML Full-text
Abstract
Biomass and tissue elemental differences were quantified for lettuce grown in deep-water conventional hydroponic conditions at two pH and alkalinity conditions. Nutrient solutions were created using inorganic salts and either reverse osmosis (RO) water or municipal water with high alkalinity. Three treatments were
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Biomass and tissue elemental differences were quantified for lettuce grown in deep-water conventional hydroponic conditions at two pH and alkalinity conditions. Nutrient solutions were created using inorganic salts and either reverse osmosis (RO) water or municipal water with high alkalinity. Three treatments were evaluated: (a) nutrient solution created with reverse osmosis (RO) water and maintained at pH 5.8 (H5); (b) same as H5 but maintained at pH 7.0 (H7); and (c) nutrient solution created using municipal water and maintained at pH 7.0, referred to as HA7. Averaged across three trials, the HA7 and H7 treatments produced 26% less shoot fresh weight (FW) than the H5 treatment with an 18% reduction in dry weight (DW). The H5 treatment had the least biomass in root FW and DW. In tissue elemental analyses, both the pH 7.0 treatments showed lower concentrations than H5 in Cu, N, Mo, and Sr, and increased concentrations in Ba, Mg, Na, and Zn. There were no differences in Al, C, Ca, Fe, K, Mn, Ni, P, S, and Si concentrations among treatments (p = 0.05). The results from this experiment can be used to isolate the effects of pH and alkalinity in aquaponic conditions where pH and alkalinity will mimic HA7 conditions. Full article
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Open AccessCommunication Productivity Benefits from Plastic Mulch in Vegetable Production Likely to Limit Adoption of Alternate Practices that Deliver Water Quality Benefits: An On-Farm Case Study
Horticulturae 2017, 3(3), 42; doi:10.3390/horticulturae3030042
Received: 4 June 2017 / Revised: 8 July 2017 / Accepted: 18 July 2017 / Published: 21 July 2017
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Abstract
Intensive tillage, high fertiliser inputs, and plastic mulch on the soil surface are widely used by vegetable growers. A field investigation was carried out to quantify the impact of alternate land management and fertiliser practices designed to improve offsite water quality on the
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Intensive tillage, high fertiliser inputs, and plastic mulch on the soil surface are widely used by vegetable growers. A field investigation was carried out to quantify the impact of alternate land management and fertiliser practices designed to improve offsite water quality on the productivity of vegetable rotations within a sugarcane farming system in a coastal region of subtropical northeast Australia. Successive crops of capsicum and zucchini were grown in summer 2010–2011 and winter 2011, respectively, using four different management practices. These were ‘Conventional’—the current conventional practice using plastic mulch, bare inter-rows, conventional tillage, and commercial fertiliser inputs; ‘Improved’—a modified conventional system using plastic mulch in the cropped area, an inter-row vegetative mulch, zonal tillage, and reduced fertiliser rates; ‘Trash mulch’—using cane trash or forage sorghum residues instead of plastic mulch, with reduced fertiliser rates and minimum or zero tillage; and ‘Vegetative mulch’—using Rhodes grass or forage sorghum residues instead of plastic mulch, with minimum or zero tillage and reduced fertiliser rates. During the second vegetable crop (zucchini), each management practice was split to receive either soil test-based nutrient inputs or a common, luxury rate of nutrient addition. The ’Trash mulch’ and ‘Vegetative mulch’ systems produced up to 43% lower capsicum and zucchini yields than either of the plastic mulch systems. The relative yield difference between trash systems and plastic mulch management systems remained the same for both the soil test-based and high nutrient application strategies, suggesting that factors other than nutrition (e.g., soil temperature) were driving these differences. Full article
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Open AccessArticle Growth and Tissue Elemental Composition Response of Butterhead Lettuce (Lactuca sativa, cv. Flandria) to Hydroponic and Aquaponic Conditions
Horticulturae 2017, 3(3), 43; doi:10.3390/horticulturae3030043
Received: 29 April 2017 / Revised: 14 July 2017 / Accepted: 19 July 2017 / Published: 26 July 2017
Cited by 1 | PDF Full-text (1753 KB) | HTML Full-text | XML Full-text
Abstract
The primary objective of this research was to compare lettuce performance under conventional hydroponics at pH 5.8 (referred to as H5), hydroponics at pH 7.0 (referred to as H7), and recirculated aquaponic water at pH 7.0 (referred to as A7). Aquaponic nutrients were
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The primary objective of this research was to compare lettuce performance under conventional hydroponics at pH 5.8 (referred to as H5), hydroponics at pH 7.0 (referred to as H7), and recirculated aquaponic water at pH 7.0 (referred to as A7). Aquaponic nutrients were supplied by continuously recirculating water between a fish rearing system (recirculating aquaculture system or RAS) and the lettuce growing system (with the sole addition being chelated iron). This paper builds upon our previous research where we found that H7 produced 26% less shoot fresh weight (FW) growth than H5 and an 18% reduction in dry weight (DW). In this research, we also evaluated the inorganic hydroponics nutrient solution at pH 7.0 (H7) to provide continuity between experiments and to isolate the pH effect. The A7 plant biomass responses were not different from H5 in all biomass response categories. H7 was different from H5 in shoot FW, DW, and DW/FW, as well as root FW and DW. H7 was different from the A7 in shoot FW, DW/FW, and root DW. There were no tissue elemental differences between H5 and H7 except Cu. The Ca and Na contents differed between H5 and A7, while the microelements Mn, Mo, and Zn differed. Generally, the elemental tissue differences between treatments were proportional to the differences for the same elements in the nutrient solutions. Aquaponic systems are often viewed to be more complicated and more risky because two complex systems are being joined (hydroponics plus RAS). However, the aquaponics system proved to be surprisingly simple to manage in daily operations. Our data suggested that the aquaponics system (A7), which was operated at a higher pH 7.0, was able to offset any negative biomass and elemental effects that occurred in the inorganic hydroponic pH 7.0 treatment (H7) from its increased pH and less optimized nutrient solution elemental concentrations. Full article
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Open AccessArticle Quantifying Postharvest Loss and the Implication of Market-Based Decisions: A Case Study of Two Commercial Domestic Tomato Supply Chains in Queensland, Australia
Horticulturae 2017, 3(3), 44; doi:10.3390/horticulturae3030044
Received: 8 July 2017 / Revised: 23 July 2017 / Accepted: 1 August 2017 / Published: 5 August 2017
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Abstract
Abstract: Using a multi-disciplinary approach, this study quantifies horticultural postharvest losses of two medium-sized (annual pack volume 4500 t) commercial, domestic, tomato supply chains. Quantification of loss was based on weight or volume, consistent with direct measurement methods of the Food Loss and
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Abstract: Using a multi-disciplinary approach, this study quantifies horticultural postharvest losses of two medium-sized (annual pack volume 4500 t) commercial, domestic, tomato supply chains. Quantification of loss was based on weight or volume, consistent with direct measurement methods of the Food Loss and Waste Accounting and Reporting Standard 2016 and qualitative techniques were used to identify the drivers of the loss and contextualise the findings. Postharvest loss was found to be between 40.3% (55.34 t) and 55.9% (29.61 t) of the total harvestable product. It was determined that between 68.6% and 86.7% of undamaged, edible, harvested tomatoes were rejected as outgrades and consequently discarded due to product specifications. Between 71.2% and 84.1% of produced tomatoes were left in the field and not harvested. This study highlights significant factors contributing to high levels of food loss and waste. Edible products are being removed from the commercial food supply chain, rejected as outgrades deemed cosmetically defective due to market-based decisions. With only 44.1% and 59.7% of the harvestable crop reaching the consumers of the two supply chains, respectively, it is perhaps more appropriate to describe a food “waste” chain as opposed to a food “supply” chain. Full article
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Open AccessArticle Compatibility of Ten Elite Cocoa (Theobroma cacao L.) Clones
Horticulturae 2017, 3(3), 45; doi:10.3390/horticulturae3030045
Received: 14 February 2017 / Revised: 24 July 2017 / Accepted: 3 August 2017 / Published: 5 August 2017
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Abstract
One way of boosting cocoa productivity which has plummeted over the last decade in Côte d’Ivoire is to introduce high performing clones. Preliminary observations have indicated that these new clones have differing growth patterns and agronomic traits in the field. Assessing their compatibility
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One way of boosting cocoa productivity which has plummeted over the last decade in Côte d’Ivoire is to introduce high performing clones. Preliminary observations have indicated that these new clones have differing growth patterns and agronomic traits in the field. Assessing their compatibility is of paramount importance since these clones will be made available to the farmers in the near future. This study was conducted in Soubré, southwest of Côte d’Ivoire, to evaluate the compatibility of ten new cocoa clones (coded as C1, C8, C9, C14, C15, C16, C17, C18, C20, and C21). A half diallel design consisting of 10 self-pollinations and 45 inter-crosses, replicated three times, was used. Results showed significant differences among clones for pollination success. Out of the ten clones evaluated, six (C1, C8, C9, C15, C17 and C21) were self-compatible. With a 39% mean pollination success, C9 was quite interesting because it has been reported to be among the highest yielding clones. Introduction of improved germplasm will go a long way towards enhancing productivity in Côte d’Ivoire, radically impact farmers’ livelihoods, and contribute significantly to a more reliable supply of cocoa beans for chocolate manufacturers. Full article
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Open AccessArticle Microbial Effects on the Production of Aquaponically Grown Lettuce
Horticulturae 2017, 3(3), 46; doi:10.3390/horticulturae3030046
Received: 26 April 2017 / Revised: 21 July 2017 / Accepted: 2 August 2017 / Published: 8 August 2017
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Abstract
In the study of aquaponics, questions have risen concerning the role of microbiota upon plant growth. This experiment compared unaltered aquaponic nutrient solution at pH 7.0 (treatment A7) with sterilized aquaponic nutrient solution at pH 7.0 (treatment SA7) to quantify effects that live
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In the study of aquaponics, questions have risen concerning the role of microbiota upon plant growth. This experiment compared unaltered aquaponic nutrient solution at pH 7.0 (treatment A7) with sterilized aquaponic nutrient solution at pH 7.0 (treatment SA7) to quantify effects that live microorganisms had on the growth of lettuce (Lactuca sativa). Baseline comparisons were made to conventional hydroponic conditions using inorganic nutrients at pH 5.8 (treatment H5) or pH 7.0 (treatment H7), which showed a 51% reduction in lettuce fresh weight (FW) growth, indicating a strong negative effect of the higher pH nutrient solution; a similar large difference (38%) occurred for dry weight (DW) comparisons between these two treatments. No difference occurred between the sterilized aquaponic treatment (SA7) and H5 in FW or DW. H5 produced more FW and DW than the non-sterile aquaponic treatment (A7). Responses were not different in FW and DW between the two aquaponic conditions. Reduced FW and DW of A7 compared to H5 may be related to the 50 times higher microbial community living in the A7 treatment water than in H5 at the beginning of each trial. Given that the sterile aquaponic solution SA7 and the H5 hydroponic condition were not different in performance, we concluded that the beneficial effects of the microbial community in the fish recirculating aquaculture system (RAS) occurred before the water was sterilized. An interesting implication of our findings is that an RAS can be decoupled from the hydroponic growing system, since its benefits are not dependent upon continuous recirculation between the plant and fish system and its living biotic community. Full article
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Open AccessArticle Plant Water Status Indicators for Irrigation Scheduling Associated with Iso- and Anisohydric Behavior: Vine and Plum Trees
Horticulturae 2017, 3(3), 47; doi:10.3390/horticulturae3030047
Received: 8 May 2017 / Revised: 20 July 2017 / Accepted: 7 August 2017 / Published: 12 August 2017
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Abstract
Plant water status indicators have been increasingly used for scheduling irrigation. Different variables may be used to do this, depending on personal preferences and the resources available. Many studies have suggested that selection of an indicator should take into account plant behavior in
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Plant water status indicators have been increasingly used for scheduling irrigation. Different variables may be used to do this, depending on personal preferences and the resources available. Many studies have suggested that selection of an indicator should take into account plant behavior in relation to isohydricity. In two Iberian studies, deficit irrigation (DI) was applied in a vineyard and in a plum orchard while plant water status and fluxes were monitored. These case-studies are discussed with special focus on the use of predawn leaf water potential (Ψpd) versus stem water potential (Ψst) to determine whether Ψst performed better and would therefore be the preferred stress indicator for plants exhibiting anisohydric behavior. In contrast, in plants with isohydric behavior, Ψpd would be generally preferred. This hypothesis seems to be supported by the present results obtained and by prior studies. The cultivars used and the intensity of stress applied have an important influence on the results. This suggests that, if no specific information is available from the existing literature, daily preliminary studies would be recommended prior to application in order to select the most appropriate plant water stress indicators. Full article
(This article belongs to the Special Issue Refining Irrigation Strategies in Horticultural Production)
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Open AccessArticle Yield Performance of Organic Sweetpotato Varieties in Various Mulches
Horticulturae 2017, 3(3), 48; doi:10.3390/horticulturae3030048
Received: 22 June 2017 / Revised: 22 July 2017 / Accepted: 26 July 2017 / Published: 17 August 2017
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Abstract
Interest in organic sweetpotato production in the United States has been growing as consumers and producers are becoming increasingly concerned about how their food is cultivated. Thus, there is a growing need for information on sweetpotato production and variety selection under an organic
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Interest in organic sweetpotato production in the United States has been growing as consumers and producers are becoming increasingly concerned about how their food is cultivated. Thus, there is a growing need for information on sweetpotato production and variety selection under an organic management production system. The objective of this study was to evaluate the effects of various mulches on yields—total and marketable—of fourteen sweetpotato varieties grown under organic management. Three types of mulch, wheat straw, pine needle, and black plastic, and a control (no mulch) were evaluated during the 2016 growing season. The wheat straw mulch yielded significantly higher yields than the black plastic and pine needle mulch treatments, though it was not significantly different from the control. The total and marketable yields of sweetpotato roots also varied significantly among the varieties, ranging from 39,719 kg·ha−1 for Beauregard to 4925 kg·ha−1 for O’Henry. There was a significant interaction between variety and mulch treatment on total but not marketable yield. More research is needed to ascertain the stability of the effects of varieties, mulch treatment, and their interactions on total and marketable yields and to elucidate other treatments and varieties with better potential to improve sweetpotato yields in organically managed production systems. Full article
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