F. Pedrero

Combined effects of water stress and fruit thinning on fruit and vegetative growth of a very early-maturing peach cultivar: assessment by means of a fruit tree model, QualiTree

Regulated deficit irrigation strategies are common practices in areas with low water availability. Thus, water stress, which can limit fruit growth, is imposed to the trees. Fruit thinning can be used to relieve this water stress in peach. In this paper, the ability of an existing fruit tree model (QualiTree) for describing the effects of water stress and fruit thinning on peach fruit and vegetative growth was assessed. The model was parameterized and calibrated for a very early-maturing peach cultivar (“Flordastar”). Important parameters were those expressing the effect of distance between organs on carbon exchange within the tree, the potential dry masses, and the relative growth rates of fruits and leafy shoots. Then, the model was tested in a wide range of water stress situations and three fruit thinning intensities: no thinning, commercial thinning, and heavy thinning. Fruit and vegetative growth simulations were consistent with observed data derived from 2006 field experiments. The variability over time of fruit and vegetative growth was well predicted. The model reproduced reductions in fruit growth observed in field experiments. It also reacted to simulated scenarios that combined water stress and thinning. Increasing thinning intensity reduced total fruit yield but increased fruit size at harvest, compensating the negative effects of water stress on fruit growth. These simulations broadened the predictive capabilities of the model and showed that it might be a useful tool in the design of innovative horticultural practices.

Incorporating Non-market Benefits of Reclaimed Water into Cost-Benefit Analysis: A Case Study of Irrigated Mandarin Crops in southern Spain

Maintaining a river system’s minimum water flow is a pre-condition for achieving the “good ecological status” prescribed by the European Water Framework Directive (WFD). In areas of water scarcity the reuse of treated water for agricultural irrigation is seen as a promising option to reduce the quantitative pressure on the resource. As part of assessing the viability of reclaimed water use in agriculture, and in accordance with the economic principles underpinning the WFD, a comprehensive economic analysis of this irrigation option is needed. This paper contributes to fill this knowledge gap by producing a cost-benefit analysis (CBA) of the use of reclaimed water in agriculture. The costs and benefits of reclaimed water use on an experimental mandarin farm in the south-east of Spain are compared with those of using surface water and a mixture of water sources. The novelty of this study is that non-market benefits are incorporated in the CBA. We thereby account for the increase in welfare that the environmental services of this supply option provide to society at large. These kind of “intangible” benefits are often ignored, but only the combination of market and non-market costs and benefits can produce a balanced assessment of water management options and lead to an efficient and sustainable allocation of the resource. Our results suggest that at the private and social level, when environmental benefits are included, the use of a mixture of water sources, including reclaimed water, seems the best option. However, at low mandarin prices (lower than 0.23 €/kg) the exclusive use of reclaimed water seems the most beneficial option.

Effectiveness and persistence of arbuscular mycorrhizal fungi on the physiology, nutrient uptake and yield of Crimson seedless grapevine

In the present study, carried out in South-eastern Spain, a commercial arbuscular mycorrhizal fungus (AMF; Glomus iranicum var. tenuihypharum sp. nova ) was introduced through drip irrigation to inoculate Crimson grapevines. Their effects on the physiological and nutritional activity were evaluated for 2 years (2011–12). Additionally, during the second year of experimentation, the persistence of mycorrhizae on the grapevine and their effects were innovatively analysed. The AMF satisfactorily colonized the Crimson grapevine roots, improved the plants water status, induced an improvement in the photosynthetic performance that increased the water use efficiency, promoted the uptake of phosphorus (P), potassium (K) and calcium (Ca) and led to a mobilization of starch reserves in the apex in winter, which was possibly responsible for enhancing root development. Moreover, inoculated plants had significantly increased yield and improved quality of grapes, which led to early grape maturation. Overall, the persistent effect of AMF during the second year produced similar positive effects, although to a lesser extent, to those obtained in the inoculated treatment. The results found in the present study show that this AMF application technique can be recommended for sustainable agriculture in arid and semi-arid areas. Moreover, as a result of the competition with the native mycorrhizae, periodic monitoring of the percentage of mycorrhizal colonization and re-inoculation in order to obtain all the positive effects evidenced in the inoculated treatment is recommended.

Influence of irrigation with saline reclaimed water on young grapefruits

ABSTRACT The use of non conventional water resources, as strategy to an efficient water management, is receiving greater attention. We have designed an experiment, during four year under field conditions in a commercial grapefruit orchard located in Campotejar (Murcia, Spain). The main objective was to evaluate the effects of irrigation with saline reclaimed water compared with traditional irrigation water (Tajo-Segura water transfer) on growth, leaf mineral content, plant and soil water status, yield, and fruit quality. Na, B and Cl concentrations exceeded the recommended level in reclaimed water, for this reason, soil salts accumulation and infiltration problems were observed during last season in this treatment. Leaf B concentration was over the phytotoxic limit in reclaimed water plants, although no visual toxicity symptoms were observed. No differences were observed concerning to leaf Cl and Na concentration. The canopy volume, the number of fruits per trees, and the total yield were reduced by the e...

Water and wastewater quality assessment based on fuzzy modeling for the irrigation of Mandarin

AbstractA fuzzy model was designed to characterize the quality of mandarin irrigation water. The model consisted of individual cascade submodels. This procedure simplifies the process, and on the other hand allows us to study the effect of individual variables in the final decision. Precisely, the effect of three irrigation water resources (Irrigators association water (IW), Reclaimed Water, and Transferred Water) were studied on the development of mandarin’s tree crop. The application of the model showed that the IW irrigation gives the best results.

Physiological and growth responses of young tomato seedlings to drip-irrigation containing two low doses of the arbuscular mycorrhizal fungus Glomus iranicum var. tenuihypharum sp. nova

Summary Two different doses of an arbuscular mycorrhizal fungus (AMF; Glomus iranicum var. tenuihypharum sp. nova) were applied through a drip irrigation system to evaluate their effects on the physiological, nutritional, and agronomic performance of tomato plants. Trials were conducted in south-eastern Spain under controlled greenhouse conditions from September – December 2012. The high rate of AMF colonisation at both doses applied improved plant growth performance, leading to significant increases in leaf macro- (N, P, K, Ca and Mg) and micro- (Fe, Cu, Zn, Mn and B) nutrient concentrations. The AMF present in colonised plants not only exerted some control over the rate of transpiration (stomatal control), but also maintained a higher rate of net photosynthesis and hence improved the intrinsic water use efficiency (computed from the ratio of the rate of net photosynthesis:stomatal conductance). In addition, a close relationship was found between the respiratory activity of the AMF and the rate of net photosynthesis, leaf N, P, Fe, and K concentrations, and fruit yield (expressed as the product of the average number of fruit × the average fruit weight in each treatment). In summary, the application of AMF was effective at improving the performance (i.e., the growth, nutrition, and yield) of tomato plants cultivated under an intensive fertigation regime.