Abstract Despite the potential of Koga Irrigation Scheme in North-Western Ethiopia for watermelon production, yields remain low due to suboptimal sowing dates and inadequate pruning practices. A field experiment was conducted during the 2021/2022 post rainy season to evaluate the effects of sowing date (November, December and January) and vine density (unpruned, 2, 3 and 4 vines) on watermelon growth and yield. The study used a factorial arrangement within a randomized complete block design with three replications. The results revealed that phenology, growth and yield parameters were significantly (P < 0.05) influenced by both factors. The highest marketable fruit yields were achieved from seeds sown in January (45.7 t ha⁻¹) and plants maintained with three vines (42.15 t ha⁻¹). Furthermore, partial budget analysis indicated that the combination of January sowing and three-vine pruning yielded the highest net benefit of 21,594.46 USD ha⁻¹ and an exceptional marginal rate of return of 1720.39%. In conclusion, sowing watermelon in January and maintaining three vines per plant is recommended to maximize marketable yield and economic returns in the Koga Irrigation Scheme and similar agro-ecologies. Significance of the study This study addresses the productivity gap for smallholder farmers in Koga Irrigation Scheme by providing evidence-based solutions for two critical management hurdles: sowing timing and vine density. To bridge the gap from initial agricultural challenges to scalable economic solutions, the study evaluates the following three core dimensions. What was already known about this subject? Koga Irrigation Scheme in North-Western Ethiopia possesses substantial agro-ecological potential and ample water sources for cultivating high-value, fast-growing horticultural crops like watermelon. Despite this natural potential, localized watermelon yields remained critically low and highly variable. It was recognized that improper agronomic practices, specifically suboptimal sowing timelines and inadequate or missing vine pruning management, were the primary constraints dragging down crop productivity. What are the new findings? The study pinpointed January as ideal sowing month, which significantly enhances crop's phenology, growth and marketable fruit yield to a peak of 45.7 t ha⁻¹. Pruning plants to maintain precisely three vines optimizes vegetative density and fruit production, delivering a high marketable yield of 42.15 t ha⁻¹. Combining a January sowing date with a three-vine pruning structure generates ultimate financial outcome: a massive net benefit of 21,594.46 USD ha⁻¹ and an exceptional marginal rate of return (MRR) of 1,720.39%. What are the expected impacts on horticulture? The study replaces arbitrary farming habits with data-driven standards, giving extension services concrete guidelines (January planting and three vine management) to pass on to smallholders. Transitioning to these optimized strategies can vastly improve farm-gate revenue, shift households away from less profitable traditional crops and enhance local supply chain efficiency for fruits. Because these findings target specific environmental responses, they can be confidently replicated across similar agro-ecologies throughout Ethiopia, maximizing the return on investment for regional large-scale irrigation infrastructure.
Abstract The use of insect-proof nets (IPNs) are an environmentally friendly physical method for preventing insect pests from entering the greenhouse and damaging the vegetables. Bok choy Brassica rapa L. subs. chinensis Brassicaceae, a widely cultivated vegetable in China, is commonly planted in the conventional greenhouses built with plastic films (PFs), IPNs and sliding doors (SDs), and named as PF-SD. However, the effectiveness of controlling agricultural insect pests in PF-SD greenhouse is low due to improper mesh sizes of IPNs and easily-deformative SDs. In this study, the rainproof performance of IPN-ZD greenhouse was compared with that of the open field, and the effects of pest damage, temperature and relative humidity as well as the growth and metabolites of bok choy in the novel greenhouse (IPN-ZD) equipped with 29-mesh IPNs and zipper doors (ZDs) were compared with those of the PF-SD greenhouse at Nanjing, China (31.5°N, 119.0°E) in autumn. The results indicated that the IPN-ZD greenhouse was able to reduce rainfall infiltration compared to that of the open field and increased the yield by 44.9%, reduced internal temperatures, significantly reduced the leaf damage rate from 15.93% to 5.94% and metabolite contents (chlorophyll a and chlorophyll b) in bok choy compared with those in the PF-SD greenhouse. In conclusion, the IPN-ZD greenhouse could reduce the leaf damage rate, improve the integrity, yield and quality of bok choy and is potentially beneficial to the environment and ecology compared with the PF-SD greenhouse. Significance of the study What was already known about this subject? Insect-proof nets (IPNs) are widely used in greenhouse vegetable cultivation as a physical pest control measure. However, their effectiveness can be affected by inappropriate mesh sizes, inadequate sealing and ventilation conditions. What are the new findings? This study developed a novel greenhouse structure equipped with 29-mesh IPNs and zipper doors (IPN-ZD). Compared with the conventional PF-SD greenhouse, the IPN-ZD greenhouse significantly reduced the leaf damage rate from 15.93% to 5.94% and increased bok choy yield by 44.9% without pesticide application. It also reduced rainfall infiltration and internal temperature. What are the expected impacts on horticulture? The IPN-ZD greenhouse provides a practical physical pest-management approach for protected vegetable production, with the potential to reduce leaf damage and improve crop yield while supporting environmentally sustainable horticultural production.
Abstract Research on strawberry cultivation using nets has dealt with shade factors below 50%. Our research investigated the performance of strawberry under a diffuse-polyethylene tunnel with an extra reduction of radiation by blue, beige and black nets (80% shade). ‘Fronteras’ strawberry plants were grown below three net treatments (blue, beige and black) and compared with plants without shade netting. They were compared in a randomized complete block design with three replications and four bags (plants) per experimental unit. Spectra behaved differently below nets. Also, photosynthetically active radiation (PAR) was higher for the plants without shade netting followed by the beige, blue and black nets (646.2, 314.1, 248.5 and 144.4 μmol m−2 s−1, respectively). Black nets resulted in lower leaf SPAD (Soil Plant Analysis Development) chlorophyll index (45–49 units), and there were no differences among the other treatments in this variable. Compared with the treatment without nets, blue and black nets reduced final total dry weight and blue and beige nets decreased final root-to-shoot ratio; also, blue and black nets increased specific leaf area. Fruit size was not affected by treatments, but black and blue nets decreased yield. Plants under beige nets had a yield similar to plants without shade netting. Apparently, strawberry under intense beige shades may perform relatively similar to plants under plastic tunnels. Significance of the study What is already known on this subject? Shade nets are innovative tools used in horticulture which modify light environment below them. Colour added to shade nets has effects on physiology and morphology of the plant that may benefit plant performance. What are the new findings? Strawberry plants thrive under intense shade resulting from shade factors of 80% of the shading nets. Colour of the net affects differently but plants under beige net may grow and yield similarly to plants without shade. What are the expected impacts on horticulture? A higher shade factor of nets may be used in strawberry culture in a changing environment challenged by increasing temperature and reduced relative humidity.
Abstract Traditional soil-based lettuce cultivation is limited by constrained space, soil-borne pathogens, variable produce quality and difficulties in achieving year-round production. Hydroponic systems present a viable alternative; however, comparative data on system–cultivar interactions under Nepalese conditions are limited. This study aims to identify an efficient hydroponic system for improving lettuce growth and quality. The experiment was conducted to evaluate the growth performance and biochemical quality of four lettuce cultivars (‘Green Span’, ‘New Red Fire’, ‘Lollo Rossa’ and ‘Black Rose’) under three production systems: nutrient film technique (NFT), deep-water culture (DWC) and soil-based cultivation for off-season production in Nepal. The experiment was conducted at Khumaltar, Lalitpur, from July to September 2023 using a combined randomized complete block design with four replications. Growth parameters and biochemical traits were assessed at 28 and 42 days after transplanting. The NFT system significantly enhanced vegetative growth, recording the highest fresh weight (90.5 g) at 28 DAT compared to DWC (47.4 g) and soil-based cultivation (17.1 g). ‘Green Span’ exhibited superior biomass accumulation and vegetative vigour across all systems. At 42 DAT, the interaction between production system and cultivar significantly affected lettuce fresh weight. ‘Green Span’ grown under the soil-based system recorded the highest fresh weight, followed by plants grown under the NFT system, indicating a cultivar-specific response during post-harvest regrowth. While hydroponic systems maximized growth parameters, soil-based cultivation resulted in higher total soluble solids and titratable acidity. Anthocyanin accumulation was highest in ‘Black Rose’ and ‘Lollo Rossa’, particularly under soil conditions, whereas ‘Green Span’ and ‘Lollo Rossa’ showed higher vitamin C content. Overall, the results demonstrate significant cultivar × production-system effects, highlighting the importance of selecting suitable combinations for off-season lettuce production. Significance of this study What is already known on this subject? Hydroponic systems are widely recognized for improving lettuce growth and productivity compared with conventional soil cultivation. Continuous nutrient availability and favourable root-zone conditions in hydroponics enhance nutrient uptake and plant development. Lettuce performance is also known to vary among cultivars due to genetic differences in growth and resource-use efficiency. What are the new findings? The study provides novel comparative information on NFT, DWC and soil-based lettuce production under off-season conditions in Nepal, including post-harvest regrowth. It provides a basis for improving off-season and potentially year-round lettuce production. The results further identified cultivar-specific responses, highlighting differences in adaptability to hydroponic environments. What are the expected impacts on horticulture? The findings provide practical guidance for selecting suitable lettuce cultivars and hydroponic systems to maximize productivity and quality. Adoption of NFT technology can improve resource-use efficiency, shorten production cycles and increase yield. These outcomes can support the expansion of sustainable, year-round leafy vegetable production, particularly in regions with limited arable land and water resources.
Abstract True cost accounting (TCA) provides a holistic and systemic approach to evaluating the hidden costs of our prevailing food system on the environment, health and society. Globally, Food and Agriculture Organisation (FAO) estimates that these hidden costs currently approach some USD 12.7 trillion per annum, with FAO and the Food Systems Economics Commission (FSEC) estimating the cost of rectifying the damage to be between USD 200 and 500 billion per annum to 2050. Fortuitously, there is an increasing international recognition of the need to transform agrifood systems towards greater efficiency, resilience, inclusiveness and sustainability as a necessary condition for realizing the 2030 Agenda for Sustainable Development. TCA can contribute to this process by assisting governments, businesses and other stakeholders in making more informed decisions to improve sustainability. Significance of the study What is already known on this subject? Evaluating the performance of food systems purely on the basis of productivity per unit area ignores significant environmental, biodiversity, health, and social costs. True Cost Accounting (TCA) is increasingly recognized as a framework for capturing these hidden impacts. What are the new findings? This article highlights the scale of hidden agrifood system costs and discusses how TCA can support more informed decision-making and accelerate the transition to sustainable agrifood systems. What are the expected impacts on horticulture? Horticulture is well placed to benefit from the transition to more healthy diets and TCA can help demonstrate the broader value of horticultural products.
