A framework for assessing irrigation performance

A comprehensive framework for conceptualizing irrigation performance is presented which, by clarifying relationships among the many incommensurate approaches to performance assessments, can provide the basis for more systematic comparative assessments of irrigation. Irrigation systems are carefully defined, and their relationships to broader agricultural and socioeconomic systems specified in terms both of goals and of inputs and outputs. Goals are seen as crucial to performance assessments, and the existence of many sometimes conflicting goals requires both specification of whose goals are being considered and clarification as to whether the goals are related to inputs, to outputs or to efficiency. Assessments can be categorized according to their purpose, with significant differences among those that monitor operational performance, those that facilitate interventions to improve performance, and those that promote accountability within an operating agency. Assessments also differ in the types of performance measures used. Three distinct categories of performance measures are identified: process measures, which relate to a system's internal operations; output measures, which focus on a system's final output; and impact measures, which pertain to the effects that the system's outputs induce in its larger environment. Performance measures are distinguished from performance standards which may be established from a variety of sources.Earlier versions of this paper were presented at the Symposium on Performance Evaluation of Irrigation systems held at the International Irrigation Management Institute, Colombo, Sri Lanka on November 23, 1989, and at a Workshop on Irrigation Performance held in Pangbourne, England, February 15–16, 1990.     

Infrared Spectroscopy‐Based Metabolomic Analysis for the Detection of Preharvest Sprouting in Grain

Preharvest sprouting of grains causes significant losses to growers and buyers. The problem occurs throughout the world, and economic losses can be millions of dollars. Visual assessment of germination is ineffective because even grains showing no external signs (e.g., having a visible shoot) may still have germinated sufficiently so that it is no longer possible for high‐quality products to be made from them. Current procedures to determine whether a grain has germinated are based around measuring enzyme or starch levels. However, despite protracted efforts to develop enhanced ways to measure germination over the last 50 years, there are currently no sufficiently accurate or reliable approaches available. The present work assesses the potential for infrared spectroscopy‐based metabolomic profiling to assess the germination of barley and wheat. The results indicate that mid‐ and near‐infrared spectroscopy are able to determine if the grain has germinated and give an indication of how long the germination process has been occurring. Both techniques are already well established in the grain industry and have the potential to form the basis of a simple, fast dockside test that would allow segregation of sound and mildly sprouted grain.     

Composition, structure and dynamics of Dysart Woods, an old-growth mixed mesophytic forest of southeastern Ohio

Dysart Woods is a 23 ha old-growth remnant of mixed mesophytic vegetation located in southeastern Ohio, USA. A designation of mixed mesophytic for this forest has historically been difficult, in part due to the abundance of white oak (Quercus alba); however, the dominance of a variety of other hardwoods prevents a simple oak forest designation. Using two 0.35 ha plots on opposing north- and south-facing slopes, we describe the structure and composition of the overstory, understory, and soils, 30 years after their first examination. In 1970, the woods was dominated by beech (Fagus grandifolia), white oak, and sugar maple (Acer saccharum) — historically, the three most abundant species in this region. At that time, white oak was only present in the largest size classes, was not regenerating, and was predicted to decline in importance through succession. These patterns continue today suggesting that inferences made via overstory–understory relations in regards to forest succession are relatively robust over this time period. Beech and maple have increased in importance; white oak has decreased in importance due to mortality in the larger size classes and decreasing density due to regeneration failure. Coarse woody debris distributions correlated strongly with living stem species’ composition and structure implying an equilibrium balance. CWD volume and frequency were dominated by Quercus spp. A detailed analysis of forest health showed that all oak species were in severe decline. The oaks are in a disease decline spiral affiliated with a variety of pre-disposing and inciting factors which include their advanced age (>300 years), their large size (> 100 cm DBH), topography, chronic air pollution, drought, and Armillaria root rot fungus. Ca:Al molar ratios in the soil are also extremely low (<1.0) and may be having an additional detrimental effect. All other canopy species appear to be healthy. One of the unusual features of this woods is its relatively diverse and high coverage (up to 90%) understory layer. The herbaceous community was sampled throughout the growing season and found to be markedly dissimilar among sample times and habitat productivity (aspect, soil quality, and light). The role of these factors has not been as well studied for herb communities as it has for tree communities. There appears to be a relatively strong linkage between the overstory regeneration and understory coverage. While a variety of woody seedlings were discovered, most were of shade tolerant species. Only a few small seedlings of white oak were discovered, with none advancing past 30 cm in height, indicating strong competition in the understory. Furthermore, this small remnant forest patch is surrounded by an agricultural and second-growth forest matrix with many non-indigenous plants — none of which have been able to enter the woods, suggesting strong equilibrium stability of these old-growth patches. The hardwood forests of the hills region has been heavily impacted by various human cultures for thousands of years. Dendrochronological analysis of a full basal slab cut from a wind-thrown white oak revealed a fairly active period of fire following European settlement. A lack of fire during the early 1600s to mid 1700s suggests that pre-Anglo fire frequency may have been negligible. There is clearly a continued role for the preservation and study of these old-growth remnants. They remain integrally important as we attempt to understand and better manage our remaining anthropogenically disturbed landscape.     

Diameter-Selective Raman Scattering from Vibrational Modes in Carbon Nanotubes

Single wall carbon nanotubes (SWNTs) that are found as close-packed arrays in crystalline ropes have been studied by using Raman scattering techniques with laser excitation wavelengths in the range from 514.5 to 1320 nanometers. Numerous Raman peaks were observed and identified with vibrational modes of armchair symmetry (n, n) SWNTs. The Raman spectra are in good agreement with lattice dynamics calculations based on C-C force constants used to fit the two-dimensional, experimental phonon dispersion of a single graphene sheet. Calculated intensities from a nonresonant, bond polarizability model optimized for sp2 carbon are also in qualitative agreement with the Raman data, although a resonant Raman scattering process is also taking place. This resonance results from the one-dimensional quantum confinement of the electrons in the nanotube.     

A photoinduced persistent structural transformation of the special pair of a bacterial reaction center

Structural modification of photosynthetic reaction centers is an important approach for understanding their charge-separation processes. An unprecedented persistent structural transformation of the special pair (dimer) of bacteriochlorophyll molecules can be produced by light absorption alone. The nonphotochemical hole-burned spectra for the reaction center of Rhodopseudomonas viridis show that the phototransformation leads to a red shift of 150 wave numbers for the special pair's lowest energy absorption band, P960, and a comparable blue shift for a state at 850 nanometers, which can now be definitively assigned as being most closely associated with the upper dimer component. Additional insights on excited-state electronic structure include the identification of a new state.     

Mars-like soils in the Atacama Desert, Chile, and the dry limit of microbial life

The Viking missions showed the martian soil to be lifeless and depleted in organic material and indicated the presence of one or more reactive oxidants. Here we report the presence of Mars-like soils in the extreme arid region of the Atacama Desert. Samples from this region had organic species only at trace levels and extremely low levels of culturable bacteria. Two samples from the extreme arid region were tested for DNA and none was recovered. Incubation experiments, patterned after the Viking labeled-release experiment but with separate biological and nonbiological isomers, show active decomposition of organic species in these soils by nonbiological processes.     

The influence of fermentation processes and cereal grains in wholegrain bread on reducing phytate content

Wholegrain bread is generally thought of as being more healthy than white bread due to it having a higher content of dietary fibre, vitamins (especially vitamin B and E) and many important minerals. However, wholegrain bread also contains high levels of phytate (myo-inositolhexakisphosphate, InsP-6) which may bind desirable nutrients, preventing their absorption in the gut and thereby reducing the nutritional value of the end product. In order to evaluate factors influencing phytate levels, the effects of fermentation and selected wholemeal flours from rye, oats and wheat were investigated. Phytate levels were assessed using a spectrophotometric assay based on the measurement of iron with 2,2′-bipyridine. Phytate decreased in freshly ground wholegrain flour dough during the fermentation process with time of fermentation being the most important factor. Fermentation temperature was found to make only a small difference to the process of phytate reduction. Since the potential benefits of wholemeal breads incorporating various grains (e.g. oats and rye) are increasingly evident, this research has important implications for human health.     

Dwarf germplasm: the key to giant <Emphasis Type="Italic">Cannabis</Emphasis> hempseed and cannabinoid crops

After a century of banishment, both euphoric (“marijuana”) and non-euphoric (“industrial hemp”) classes of Cannabis sativa are attracting billions of dollars of investment as new legitimate crops. Most domesticated C. sativa is very tall, a phenotype that is desirable only for hemp fibre obtained from the stems. However, because the principal demands today are for chemicals from the inflorescence and oilseeds from the infructescence, an architecture maximizing reproductive tissues while minimizing stems is appropriate. Such a design was the basis of the greatest short-term increases in crop productivity in the history of agriculture: the creation of short-stature (“semi-dwarf”), high-harvest-index grain cultivars, especially by ideotype breeding, as demonstrated during the “Green Revolution.” This paradigm has considerable promise for C. sativa. The most critical dwarfing character for breeding such productivity into C. sativa is contraction of internodes. This reduces stem tissues (essentially a waste product except for fibre hemp) and results in compact inflorescences (which, on an area basis, maximize cannabinoid chemicals) and infructescences (which maximize oilseed production), as well as contributing to ease of harvesting and efficiency of production on an area basis. Four sources of germplasm useful for breeding semi-dwarf biotypes deserve special attention: (1) Naturally short northern Eurasian wild plants (often photoperiodically day-neutral, unlike like most biotypes) adapted to the stress of very short seasons by maximizing relative development of reproductive tissues. (2) Short, high-harvest-index, oilseed plants selected in northern regions of Eurasia. (3) “Indica type” marijuana, an ancient semi-dwarf cultigen tracing to the Afghanistan-Pakistan area. (4) Semi-dwarf strains of marijuana bred illegally in recent decades to avoid detection when grown clandestinely indoors for the black market. Although the high THC content in marijuana strains limits their usage as germplasm for low-THC cultivars, modern breeding techniques can control this variable. The current elimination of all marijuana germplasm from breeding of hemp cultivars is short-sighted because marijuana biotypes possess a particularly wide range of genes. There is an urgent need to develop public gene bank collections of Cannabis.