Avances recientes en la programación de los riegos

[ES] Se describe el estado actual de las distintas técnicas de programación de riegos, poniendo el énfasis en las aplicaciones de una nueva generación de sensores de humedad de suelo y de detección de estrés en planta, recientemente desarrollados. Se muestran ejemplos en los que el registro continuo de la humedad volumétrica del suelo a varias profundidades permite detectar de forma casi inmediata una dosis de riego insuficiente. La detección precoz del estrés en el propio cultivo, ya sea por teledetección o por medidas directas o indirectas en el mismo, debe conducir a manejar el riego con un elevado nivel de precisión y a modular las aplicaciones de agua para optimizar el riego. Entre todos los indicadores de estrés en planta existentes, se apunta que las medidas de contracción de tronco pueden estar entre las más sensibles a cambios en el estado hídrico del árbol. Se presentan casos donde las oscilaciones en el diámetro de los troncos pueden servir para programar los riegos de forma automática. Finalmente, se insiste en la necesidad de integrar estas nuevas técnicas en un enfoque mucho más amplio de manejo del riego, de manera que pueda generalizarse su uso.Fereres Castiel, E.; Goldhamer, DA. (2000). Avances recientes en la programación de los riegos. Ingeniería del Agua. 7(1):47-54. https://doi.org/10.4995/ia.2000.2836SWORD475471Caja Rural de Almeria (ed). 1997. Gestión del regadío en El Campo de Dalías: Las Comunidades de Regantes Sol y Arena y Sol-Poniente. 195pCampbell, G.S. y D.J. Mulla, 1990. Measurement of soil water content and potential. p.127-142. In: Irrigation of Agricultural Crops. (B.A. Stewart y D.R. Nielsen, eds.)Amer. Soc. Agric. Engn., Madison, WisFereres, E. 1996. Irrigation Scheduling and its Impact on the 21st Century. En: Proceedings of the International Conference on ET and Irrigation Scheduling. (Camp, C.R., Sadler, E.J. y Yoder, R.E., eds) ASAE, San Antonio, USA, 547-553Fereres, E., D. Goldhamer, M. Cohen, J. Girona y M. Mata. 1999. Continuous trunk diameter recording can reveal water stress in peach trees. California Agriculture. 53(4):21-25.Garnier, E. y A. Berger, 1986. Effect of water stress on stem diameter changes of peach trees growing in the field. J. App. Ecol. 23:193-209.Ginestar, C. y J.R. Caster, 1996. Utilización de dendrómetros como indicadores de estrés hídrico en mandarinos jóvenes regados por goteo. Riegos y Drenajes XXI, 89:40-46.Goldhamer, D.A. E. Fereres, M. Mata, J Girona y M. Cohen. 1999. Sensitivity of continuous and discrete plant and soil water status monitoring in peach trees subjected to deficit irrigation. Journal of the American Society for Horticultural Science. 124:4:437-444.Goldhamer D.A. y E Fereres. 2000. Scheduling fruit tree irrigation using continuous recorded trunk diameter measurements. (enviado a publicación).Grimes D.W. y H. Yamada. 1982. Relation of cotton growth and yield to minimum leaf water potential. Crop Sci. 22:134-139.Heerman, D.F., D.L. Martin, R.D. Jackson y E.C. Stegman. 1990. Irrigation scheduling controls and techniques. En: Irrigation of agricultural crops (B.A. Stewart y D.R. Nielsen, eds) American Society of Agronomy monograph no.30 p.475-508.Huck M.G. y B. Klepper. 1976. Water relation of cotton. II. Continuous estimates of water potential from stem diameter measurements. Agron. J. 69:593-597Jackson, R.D., R.J. Reginato y S.B. Idso. 1977. Wheat canopy temperature: a practical tool for evaluating crop water requirements. Water Resour Res. 13:651-656.Jackson, R.D. 1981. Canopy temperature and crop wáter stress. Adv. Irrig.,1:43-85.Martin, D.L.; E.C. Stegman, y E. Fereres. 1991: Irrigation Scheduling Principles. En: Management of Farm Irrigation Systems. (Hoffman, G.J., Howell, T.A., Solomon, K.H. eds) American Society of Agricultural Engineers, 155-203.Mata M., J. Girona, D. Goldhamer, E Fereres, M Cohen y S Johnson. 1999. Water relations of lysimeter-grown peach trees are sensitive to deficit irrigation. California Agricultural. 53(4):17-21.Moran, M.S. 1994. Irrigation management in Arizona using satellite and airplanes. Irrig. Sci. 15:35-41Paltineanu, I.C., y J.L. Starr. 1997, Real-time soil water dynamics using multisensor capacitance probes: Laboratory calibration. Soil Sci. Soc. Am. J. 61:1576-1585.Shackel, K. A., H. Ahmadi, W. Biasi, R. Buchner, D. Goldhamer, S. Gurusinghe, J. Hasey, D. Kester, B. Krueger, B.Lampinen, G. McGourty, W. Micke, E. Mitcham, B.Olson, K. Pelletrau, H. Philips, D. Ramos, L.Schwankl, S. Sibbett, R. Snyder, S. Southwick, M. Stevenson, M. Thorpe, S. Weinbaum y J. Yeager. 1997. Plant water status as an index of irrigation need in deciduous fruit trees. HortTechnology 7(1):23-29.Starr, J.L., and I.C. Paltineanu. 1998, Soil water dynamics using multisensor capacitance probes in nontraffic interrows of corn. Soil Sci. Soc. Am. J. 62:114-122

Regulated deficit irrigation reduces water use of almonds without affecting yield

A plant-based regulated deficit irrigation (RDI) experiment in the northern Sacramento Valley determined that crop consumptive water use and irrigation could be reduced without significant detrimental effects on almond production. Tree stress was measured by recording midday stem water potential, a direct measure of tree water stress. With a water stress level of −14 to −18 bars during the hull-split period, average annual water savings were about 5 inches. Over 5 years, no significant yield reductions were observed, although average kernel weight was slightly lower. The results suggest that water savings can be achieved without affecting yield, even in soils with low water-holding capacity

The Msx1 Homeoprotein Recruits G9a Methyltransferase to Repressed Target Genes in Myoblast Cells

Although the significance of lysine modifications of core histones for regulating gene expression is widely appreciated, the mechanisms by which these modifications are incorporated at specific regulatory elements during cellular differentiation remains largely unknown. In our previous studies, we have shown that in developing myoblasts the Msx1 homeoprotein represses gene expression by influencing the modification status of chromatin at its target genes. We now show that genomic binding by Msx1 promotes enrichment of the H3K9me2 mark on repressed target genes via recruitment of G9a histone methyltransferase, the enzyme responsible for catalyzing this histone mark. Interaction of Msx1 with G9a is mediated via the homeodomain and is required for transcriptional repression and regulation of cellular differentiation, as well as enrichment of the H3K9me2 mark in proximity to Msx1 binding sites on repressed target genes in myoblast cells as well as the developing limb. We propose that regulation of chromatin status by Msx1 recruitment of G9a and other histone modifying enzymes to regulatory regions of target genes represents an important means of regulating the gene expression during development

The effects of applied water at various fractions of measured evapotranspiration on reproductive growth and water productivity of Thompson Seedless grapevines

The reproductive growth and water productivity (WPb) of Thompson Seedless grapevines were measured as a function of applied water amounts at various fractions of measured grapevine ETc for a total of eight irrigation treatments. Shoots were harvested numerous times during the growing season to calculate water productivity. Berry weight was maximized at the 0.6–0.8 applied water treatments across years. As applied water amounts increased soluble solids decreased. Berry weight measured at veraison and harvest was a linear function of the mean midday leaf water potential measured between anthesis and veraison and anthesis and harvest, respectively. As applied water amounts increased up to the 0.6–0.8 irrigation treatments there was a significant linear increase in yield. Yields at greater applied water amounts either leveled off or decreased. The reduction in yield on either side of the yearly maximum was due to fewer numbers of clusters per vine. Maximum yield occurred at an ETc ranging from 550 to 700 mm. Yield per unit applied water and WPb increased as applied water decreased. The results from this study demonstrated that Thompson Seedless grapevines can be deficit irrigated, increasing water use efficiency while maximizing yields

Is complementary and alternative medicine (CAM) cost-effective? a systematic review

BACKGROUND: Out-of-pocket expenditures of over $34 billion per year in the US are an apparent testament to a widely held belief that complementary and alternative medicine (CAM) therapies have benefits that outweigh their costs. However, regardless of public opinion, there is often little more than anecdotal evidence on the health and economic implications of CAM therapies. The objectives of this study are to present an overview of economic evaluation and to expand upon a previous review to examine the current scope and quality of CAM economic evaluations. METHODS: The data sources used were Medline, AMED, Alt-HealthWatch, and the Complementary and Alternative Medicine Citation Index; January 1999 to October 2004. Papers that reported original data on specific CAM therapies from any form of standard economic analysis were included. Full economic evaluations were subjected to two types of quality review. The first was a 35-item checklist for reporting quality, and the second was a set of four criteria for study quality (randomization, prospective collection of economic data, comparison to usual care, and no blinding). RESULTS: A total of 56 economic evaluations (39 full evaluations) of CAM were found covering a range of therapies applied to a variety of conditions. The reporting quality of the full evaluations was poor for certain items, but was comparable to the quality found by systematic reviews of economic evaluations in conventional medicine. Regarding study quality, 14 (36%) studies were found to meet all four criteria. These exemplary studies indicate CAM therapies that may be considered cost-effective compared to usual care for various conditions: acupuncture for migraine, manual therapy for neck pain, spa therapy for Parkinson's, self-administered stress management for cancer patients undergoing chemotherapy, pre- and post-operative oral nutritional supplementation for lower gastrointestinal tract surgery, biofeedback for patients with "functional" disorders (eg, irritable bowel syndrome), and guided imagery, relaxation therapy, and potassium-rich diet for cardiac patients. CONCLUSION: Whereas the number and quality of economic evaluations of CAM have increased in recent years and more CAM therapies have been shown to be of good value, the majority of CAM therapies still remain to be evaluated