The tolerance of 26 native tomato collections from Mexico to Meloidogyne incongnita (Kofoid and White) Chitwood was studied to identify those with potential for use in breeding or as rootstock. To do this, 30-day-old plants were established in a hydroponic system under greenhouse conditions. A solution with 100,000 eggs-larvae per plant was applied to the substrate 10 days after transplantation (dat). Characters of the above-ground part of the plants were recorded and at 210 dat the development of nematode populations in roots was quantified. Meloidogyne incognita reduced fruit diameter and plant size (first truss height, stem dry weight, and node number), and increased the number of fruits and flowers. Additionally, it reduced root length and increased root volume due to nodule formation. By means of multivariate analysis (cluster and discriminant), five collection groups were defined based on the number of small and large galls, as well as total galls (82 % variation), and by the number of larvae in roots and eggs in the substrate (13 % variation). Three tolerant collections with low gall indices and a lower number of eggs-larvae in the roots and substrate were identified. Eight collections were moderately tolerant, nine moderately susceptible and six susceptible. No associations were detected between collection origins or fruit shape and tolerance to nematode.

Sweet potato (Ipomoea batatas L.) is a low production cost crop that is grown during almost the whole year, mainly in developing countries. In arid and semiarid regions, the presence of salinity and water stress can generate yield reductions and losses in the quality of the tuber roots. To address these issues, an experiment was performed to determine yield, N, P, K, Ca, Mg and Na uptake and proline content in plants belonging to two sweet potato cultivars with a different degree of salt tolerance, grown under three (0, 8 and 14 mmol NaCl) salt and two watering regimes (watering after two and four days), during summer-fall conditions of 2009. Salinity and watering frequencies were controlled by using the soilless culture technique. Both water and salt stresses reduced tuber root yields. The yield reduction is explained by a reduction in the uptake of N, P, K, Ca and Mg with the water stress treatment, and an increased Na uptake in the high salinity treatment. The salt and water stress adjustments were reflected in an increment in proline content in leaves and tuber roots. The results confirm the tolerant cultivar as a hardy variety adaptable to abiotic stresses, whereas the non-tolerant variety had lower yield and nutrient uptake. The results did not support the hypothesis that changes in proline content might be used as fast screening tools to discriminate between tolerant and susceptible sweet potato cultivars.

This research was conducted to evaluate the effect of root malformation in plant growth of three Citrus rootstocks, and to detect this problem based on nursery growth and development. We used seedlings of rootstocks: Citrange ‘Carrizo’, Citrumelo ‘Swingle’ (C.P.B. 4475) and ‘Volkamerian’ Lemon without and with root malformation (control = straight root; malformation 1 = sinuous root; malformation 2 = root with two angles ≥ 90° and, malformation 3 = root with three angles ≤ 90°) and 15 cm uniform length. These plants were transplanted to 20 x 34 cm black polyethylene bags with a mixture of land soil, vermicompost and agrolite (3:1:1 v/v/v). Stem length and diameter; leaf number and area; root length and volume; leaf, stem and root dry matter and shoot/root were evaluated ten months after transplanting. Stem length and diameter were higher in ‘Volkamerian’. No differences were found for root malformation. The foliar area of ‘Volkamerian’ was greater than ‘Carrizo’ and ‘Swingle’. The foliar area increased with root malformation. Root length was longer in ‘Volkamerian’ than in ‘Carrizo’ and ‘Swingle’. We observed interaction between rootstocks and root curvature level for root volume. ‘Volkamerian’ was the most vigorous rootstock. It was not possible to identify the plants with root malformation based on plant growth and development.

A study was conducted at two sites near the Universidad Autónoma Chapingo, State of Mexico, in 2001, in order to estimate the response in squash (Cucurbita pepo L.) to in situ participatory selection in terms of fruit quality and seed yield. Two native varieties from Sierra Norte de Puebla, selected in situ, were evaluated: Mazapa (selection cycles 1 to 3) and Libertad (selection cycles 1 to 3), plus a control, at a density of 27,639 plants·ha-1, in a randomized complete block design with four replications. The best response per selection cycle, based on averaging the two locations, occurred in the Mazapa variety for number of fruits per plant (0.29 fruits; 31.8 %), fruit height (1.0 cm; 6.1 %), fruit width (0.5 cm; 2.4 %), flesh thickness (0.1 cm; 5.8 %), seed height (0.034 cm; 1.6 %) and seed width (0.001 cm; 0.11 %). The Libertad variety was better in gain for seed weight per fruit (12 g·fruit-1; 21 %) and fruit weight per plant (0.1 kg·fruit-1; 6.6 %). The second selection cycle in the Mazapa variety had the best gain in fruit weight (3.77 kg), seed weight per plant (98 g), flesh thickness (2.6 cm), fruit height (23.6 cm), fruit width (20.3 cm), and seed width (0.934 cm). The third selection cycle in Mazapa showed the highest values for number of fruits per plant (1.49), fruit weight per hectare (123.5 t·ha-1), and seed yield per hectare (3.83 t·ha-1).

The effects of ammonium and nitrate on hydroponic tomato crop have been studied since hydroponics is used as a means of commercial production. In general, it has been found that small proportions of ammonium improve plant growth and yield. However, these studies were carried out with all the roots exposed to these combinations. We tested the hypothesis that separating the half of the roots and exposing this portion to high concentration of ammonium helps to increase growth, yield and fruit quality, without ammonium toxicity symptoms. For this reason, an experiment was conducted which treatments were: 1) 12 meq·liter-1 of NO3-:water; 2) 9 meq·liter-1 of NO3-:3 meq·liter-1 of NH4+; 3) 6 meq·liter-1 of NO3-:6 meq·liter-1 of NH4+; and 4) water:6 meq·liter-1 of NH4+. We used a completely randomly design with five replications. The experimental unit consisted of a tomato plant with split roots in quantities of 50 %. Each part grew up in a container divided into two parts of the same volume, which was filled with red volcano gravel called “tezontle”. Plant height, diameter, root volume and length, fruit yield per plant, fruit quality (polar and equatorial diameter, total soluble solids and titratable acidity) and shelf life were quantified. The results indicated that NO3-:NH4+ ratios had a significant effect (P ≤ 0.05) on all variables, except for root length and tritable acidity.

Hydroponic or greenhouse production systems allow daily fertilization of vegetable crops, depending on its life cycle, substrate and available water. Sawdust is currently being used successfully as substrate in crop production and for this reason we evaluate the effect of mixtures (v/v) of volcanic rock with fresh and recycled sawdust in production and nutrient extraction of tomato. A completely randomized design was used with five different treatments, T1: volcanic rock, T2: volcanic rock/recycled sawdust (20/80), T3: volcanic rock/recycled sawdust (30/70), T4: volcanic rock/fresh sawdust (20/80) and T5: volcanic rock/fresh sawdust (30/70). The maximum absorption rate occurred between 60 and 136 days after transplanting (DAT), with a similar pattern in the extraction dynamics, higher than 70 % in all treatments in a decreasing order K > N > Ca > P > Mg. The results indicate that mixtures of volcanic rock/recycled sawdust produce an equal fruit yield and efficiency of nutrient uptake than volcanic rock and mixtures of volcanic rock/fresh sawdust. This indicates that recycling the growing media is a viable alternative and may provide higher yields during several crops cycles if management is appropriate.

To improve the efficiency of the adoption of technological innovations in the cultivation of ‘Persian’ lemon in San Pedro Tlapacoyan, Veracruz and increase the fruit yield and the benefit-cost (B/C) ratio of this economic activity, we used the “methodology of logbook innovation”, which was worked with 26 growers of this community for three cycles of production (2005/2006, 2006/2007 and 2007/2008). This methodology consisted of a diagnosis, recommendations (advice), monitoring, evaluation and control of innovations made by the growers, by a professional service provider. The variables evaluated were: percentage of innovation adoptions, attributes of growers, incomes, costs of production, yields and B/C ratio. The first production cycle had a yield of 5.24 t∙ha-1 and a benefit/cost ratio of 1.55, attributable to the reduced percentage of innovations adoption of 15. After applying the proposed methodology, the income of the second cycle increased in 64 %, compared to the initial cycle, and 41 % between 2006/07 and 2007/08. The B/C ratio increased 68 % (from 1.56 to 2.28), which was associated to the increase of 29.6 per cent of innovation adoptions.

In Mexico, Dahlia flowers are commonly consumed in different type of dishes; however, there are no reports on characteristics as a functional food. Proximate composition, minerals, vitamin C, phenolic compounds, total anthocyanins, carotenoids and antioxidant activity of dahlia flowers were studied. In general, the highest values for the content of phenolic compounds, anthocyanins and antioxidant capacity were found in the purple dahlia (127.5 mg AG∙g-1, 257.5 mg pelargonidin∙100 g-1 and 24 % of inhibition respectively). The type and concentration of phenolic compounds varied according to the color of the flower. The highest phenolic compound value was for hesperidin (398.9 mg∙g-1), while the most detected phenolic compounds in the flowers were gallic and caffeic acids. Based on these results, we can recommend the consumption of dahlia flowers as functional food because it provides phenolic compounds (specially the dark-colored dahlia flowers, since they had the highest phenolic composition and antioxidant activity).

The aim of the work was to economically and environmentally optimize fertilizer use on sugar beet farms in a European region. Firstly, the difference between the applied and recommended doses was calculated, revealing that 54.72 %, 42.01 % and 14.65 % of the surveyed farms used more nitrogen, phosphorous and potassium, respectively, than recommended. Secondly, for the economic optimization, a linear programming model considering available fertilizers and prices was developed to determine the most cost-effective mix of fertilizers to use to comply with the recommended dose. If applied, these fertilizer mixes would save producers up to 22.23 €·ha-1. Finally, the CO2 equivalent emissions that could have been avoided and the CO2 emission rights that could have been negotiated if the excess N had not been applied were calculated. Specifically, 25.545.65 kg of CO2 emissions could have been avoided and 6.812 € of CO2 rights could have been traded by the whole region.