Browsing by Author "Cartmill DL"

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Allelopathic Effects of Moringa oleifera Lam. on Cultivated and Non-Cultivated Plants: Implications for Crop Productivity and Sustainable Agriculture
(MDPI (Basel, Switzerland), 2025-07-23) Kamanga BM; Cartmill DL; McGill C; Clavijo McCormick A; Mussury RM
Moringa (Moringa oleifera Lam.) is widely recognised as a multipurpose crop suitable for human and animal consumption, medicinal, and industrial purposes, making it attractive for introduction into new ranges. Its extracts have been found to have beneficial impacts on various crop species and biological activity against multiple weeds, making their use in agriculture promising. However, concerns have also been raised about moringa’s potential to negatively impact the growth and development of other cultivated and non-cultivated plant species, especially in areas where it has been introduced outside its native range. To understand the positive and negative interactions between moringa and other plants, it is essential to investigate its allelopathic potential. Allelopathy is a biological activity by which one plant species produces and releases chemical compounds that influence the reproduction, growth, survival, or behaviour of other plants with either beneficial or detrimental effects on the receiver. Plants produce and release allelochemicals by leaching, volatilisation, or through root exudation. These biochemical compounds can affect critical biological processes such as seed germination, root and shoot elongation, photosynthesis, enzymatic activities, and hormonal balance in neighboring plants. Therefore, allelopathy is an important driver of plant composition and ecological interactions in an ecosystem. This review explores the positive and negative allelopathic effects of moringa extracts on other plant species, which may help to inform decisions regarding its introduction into new biogeographical regions and incorporation into existing farming systems, as well as the use of moringa plant extracts in agriculture.
Comparative evaluation of pumice as a soilless substrate for indoor Rubus idaeus L. cultivation
(Taylor and Francis Group on behalf of the Royal Society of New Zealand, 2024-07-21) Zhao R; Sofkova-Bobcheva S; Cartmill DL; Hardy D; Zernack A; Li M
Pumice is an abundant natural resource in New Zealand and its application in horticulture could save significant costs. To investigate the effect of pumice substrates on raspberry growth and fruit quality, two dwarfing selections (sel.8 and sel.110) were grown hydroponically in (1) coconut coir (control); (2) pumice; (3) pumice/coir (50/50 v/v); (4) pumice/flax (50/50 v/v). Results showed that the addition of pumice to coir significantly increased bulk density, which provided better root anchor support for plants, and also increased the water holding capacity (WHC). Pure pumice had a higher bulk density and lower porosity compared to the other tested substrates, which enhanced fruit quality and yield, although the vegetative growth was slightly lower compared to the control. Mixed pumice/flax substrate had the lowest porosity and poorer WHC, resulting in inferior raspberry growth vigour and productivity. Our results furthermore suggested different substrates could affect the one-year-old cane height, crop yield and fruit characteristics. Pumice was more suitable for sel.8, while the pumice/coir mixture promoted a higher yield for sel.110. In conclusion, pumice and pumice-based mix substrates can be successfully used for hydroponic dwarfing raspberry production without compromising yield and fruit quality.
Daily Light Integral and Nutrient Solution Electrical Conductivity for Tomato and Bell Pepper Seedling Production in an Indoor Vertical Farm with Artificial Lighting
(MDPI (Basel, Switzerland), 2025-05-01) Adame-Adame DY; Alvarado-Camarillo D; Valdez-Aguilar LA; Cartmill AD; Cartmill DL; Soriano-Melgar LDAA; Yang Q
Indoor vertical farms (IVFs) provide the conditions for producing seedlings of good quality. However, their effectiveness depends on the daily light integral (DLI) and nutrient management. This study examined the effects of DLI and nutrient solution electrical conductivity (EC) on tomato and bell pepper seedlings produced in an IVF or a greenhouse. Seedlings in the greenhouse were harvested 45 (tomato) and 55 (bell pepper) days after sowing, while those in the IVF were harvested after 30 and 40 days, respectively. The optimal EC was 2.0 for tomato and 2.4 dS m−1 for bell pepper. Tomato seedlings showed a decreased shoot-to-root ratio in the IVF. Tomatoes in the IVF reached 241% higher total biomass than greenhouse seedlings at 31.7 mol m−2 d−1, while bell peppers had an increase of 333% at 39.6 mol m−2 d−1; however, a DLI of 23.7 mol m−2 d−1 was enough to cause an increase of 153% and 264%, respectively. Nutrient concentration decreased in IVF seedlings, which was attributed to a dilution effect; in contrast, the nutrient content of tomato and bell pepper were highest when grown in the IVF when irrigated with solutions at 2.0 dS m−1 and a DLI of 31.7 mol m−2 d−1.
Subirrigation of container-grown tomato I: Decreased concentration of the nutrient solution sustains growth and yield
(MDPI (Basel, Switzerland), 2019-10-02) García-Santiago JC; Valdez-Aguilar LA; Cartmill AD; Cartmill DL; Juárez-López P; Díaz-Pérez JC
Subirrigation of containerized vegetable crops is a promising strategy to increase water and fertilizer use efficiency. However, the nutrient solution may cause salts accumulation in the substrate top layer. The objective of this study was to determine the effect of nutrient solution concentration in container-grown tomato under surface drip-irrigation and subirrigation. The plants were irrigated with solutions at concentrations of -0.072, -0.058 and -0.043 MPa (100%, 80% and 60% of Steiner's nutrient solution, respectively). Except at the highest concentration, the greatest yields occurred in subirrigated (10.6 kg plant-1) compared to drip-irrigated plants (9.5 kg plant-1). In drip-irrigated plants, yield was higher with the highest solution concentration. The increased yield in subirrigated plants at low solution concentrations was related with increased fruit N and Ca content. The higher accumulation of N, P, K and Ca demonstrates that subirrigation allows for increased nutrient use efficiency, particularly when using nutrient solutions of low concentration. Water use efficiency was markedly increased in subirrigated tomato, as 300 to 460 g of fruit L-1 were produced, compared to 50 g L-1 in drip-irrigated plants. Our results indicate that subirrigation is a feasible system for soilless-cultivated tomato provided the nutrient solution is reduced to a 60% of the total concentration.
Subirrigation of container-grown tomato II: Physical and chemical properties of the growing medium
(MDPI (Basel, Switzerland), 2019-10-24) García-Santiago JC; Valdez-Aguilar LA; Cartmill DL; Cartmill AD; Juárez-López P; Alvarado-Camarillo D
Subirrigation of containerized vegetable crops is a promising strategy to increase water and nutrient use efficiency, however, the longer growing seasons for cultivation of vegetable species may cause marked changes in the physical and chemical substrate properties. This study determined the effects of the irrigation system, subirrigation vs. drip-irrigation, and the concentration of the nutrient solution on the substrate physical and chemical properties in containerized tomato plants. Plants were irrigated with solutions at concentrations of -0.072, -0.058 and -0.043 MPa. Root dry weight of subirrigated plants was decreased by 35% in the substrate top layer when the highest concentration was used. Substrate electrical conductivity increased while pH was acidified as solution concentration increased and from the bottom to the top substrate layers in subirrigated plants. Salts buildup was associated with increased concentration of oxalic and tartaric acids and pH acidification. The improved substrate physical and chemical properties in subirrigated plants were associated with higher fruit yield (11.0 kg per plant) provided nutrient solution concentration was reduced to -0.043 MPa; in contrast, the highest yield in drip-irrigated plants (10.1 kg per plant) was obtained when the solution concentration was -0.072 MPa. In conclusion, subirrigation with reuse of the nutrient solution is a promising strategy to reduce water waste through runoff and leaching as water use efficiency increases due to greater water retention properties in the substrate, the maintenance of an EC within a range the plants can tolerate, and a lower acidification of substrate pH.