Water status response of corn and cotton to altered irrigation

Water is a primary limiting factor to crop production and thus crop water status is essential information for management decisions. Corn and cotton were grown in the field under two constant water regimes. The low water level (WL) was 0.662PET (potential evapotranspiration) in corn and rainfall for cotton. The high water level (WH) was 1.02PET for both crops. Two transient water treatments in each crop began as the two constant water level treatments but then the water inputs were reversed and the change in water status was monitored. When the transient water treatments were initiated, corn was at the V14 and V16 growth stages in the WL and WH treatments, respectively, and cotton was 2 weeks past first bloom for both water levels. The purpose of the experiment was to compare the sensitivity of leaf water potential (LWP) and crop canopy temperature to changes in irrigation rate. The transient water treatment of each crop that relieved water stress (TLH) changed from WL to WH and the treatment which induced water stress changed from WH to WL (THL). The LWP values of the transient water treatments reversed 5 and 8 days after reversing water input rates to corn in 1998 and 1999, respectively, and after 3 days in both years for cotton. A reversal in canopy temperatures, expressed as the amount of daily time that the temperature was above 28°C (DST), was not detected between the TLH and THL treatments of corn after 25 days in 1998 or after 13 days in 1999. The DST values of the cotton transient water treatments reversed after 4 days in 1998 and 5 days in 1999, when the values of THL became greater than for TLH. Corn tassels, which apparently transpire less than leaves, were forming at the beginning of the transient water treatments and their presence in the view of the infrared thermocouples may have reduced the apparent radiometric temperature difference between the transient water treatments. During the water status adjustment period following the initiation of the transient water treatments, there were significant linear relationships between LWP and DST in cotton in both years but only in 1998 in corn. Cotton canopy temperature could be used to rapidly monitor an entire field in contrast to LWP which accurately measures plant water status but cannot provide automated measurements across a large area.     

Multivariate analysis of invasive plant species distributions in southern US forests

Landscape Ecology - Invasive plants cause significant impacts in forested areas throughout the world. However, little is known about the relative importance of environmental drivers on the...     

Molecular biology of male gametogenesis

Pollen development has been studied at a molecular level in several systems that are amenable to genetic or transgenic analysis. We have characterized several tomato genes that are expressed late in pollen development. Our goals in this research were 1) to determine the cis- and tran-acting factors that mediate pollen expression, and 2) to determine the functions of the proteins encoded by these genes. We currently favor the hypothesis that pollen-specific gene expression is mediated in a combinatorial manner. Antisense experiments have indicated an important role for the LAT52 protein during pollen hydration.     

A ram semen-collecting apparatus for mains or battery operation

Extract

This stimulator has been designed to be used by veterinary surgeons who require an instrument that is portable and can be used, not only on the A.C. mains, but also in the field, where power is not available. The number of controls has been kept to a minimum and the overall size and weight reduced to enable the stimulator to be included easily in the veterinarian's equipment bag.     

Light quality treatments enhance somatic seedling production in three southern pine species

Embryogenic cultures of loblolly pine (Pinus taeda L.), slash pine (Pinus elliottii Engelm.), longleaf pine (Pinus palustris Mill.) and slash pine x longleaf pine hybrids were initiated from immature seeds on an initiation medium containing 13.57 microM 2,4-dichlorophenoxyacetic acid and 2.22 microM benzylaminopurine. Embryogenic cultures proliferated and somatic embryos developed, matured and germinated following a modified protocol and media originally developed for radiata pine (Pinus radiata D. Don.) somatic seedling production. A discrete, light-sensitive pre-germination stage and a later germination (radicle emergence) stage were identified by the differential response of somatic embryos to light of different wavelengths. Different light quality treatments were applied during the pre-germination and germination steps, using cool white fluorescent bulbs or light-emitting diodes (LEDs), or both. In general, red wavelengths provided by LEDs during these steps resulted in higher frequencies of somatic embryo germination (up to 64%) and conversion (up to 50%), longer tap roots and more first-order lateral roots than the standard cool white fluorescent treatments or treatment with blue wavelengths from LEDs. In addition, exposure to red light allowed germination of somatic embryos of some clones that failed to produce germinants under fluorescent light. Germination and conversion were further enhanced by sequential application of cool white fluorescent light and red light, resulting in up to 100% germination and conversion in one experiment. Longleaf pine somatic embryos were especially responsive to the light quality treatments, resulting in the first report of somatic seedling production for this species.     

Mapping QTL controlling soybean seed sucrose and oligosaccharides in a single family of soybean nested association mapping (SoyNAM) population

The meal value of Soybean for monogastric animals is determined partly by sucrose, raffinose and stachyose. Of these, sucrose is desirable, while raffinose and stachyose are indigestible, causing flatulence and abdominal discomfort. The objective of this study was to identify quantitative trait loci (QTL) controlling seed sucrose, raffinose, and stachyose in a set of 140 SoyNAM (Nested Association Mapping) recombinant inbred lines (RILs), developed from the cross between lines IA3023 and LD02‐4485. A total of 3,038 SNP markers from the Illumina SoyNAM BeadChip SNP were used to map the QTLs for sucrose and the RFOs, raffinose, and stachyose. Significant genotypic differences (p < .001) among RILs were observed for sucrose, raffinose and stachyose contents across years. A 3038 Illumina SoyNAM BeadChip SNPs identified three QTLs for sucrose, one on chromosome 1, explaining 10% variance and two on chromosome 3 each explaining 22%. Raffinose QTL was detected on chromosome 6, explaining 6% variance. The mapped QTLs were novel and spanned regions harbouring candidate genes with roles in plant growth including seed development.     

Influence of head positioning on the assessment of Chiari-like malformation in Cavalier King Charles spaniels

Chiari-like malformation (CM) is almost omnipresent in the Cavalier King Charles spaniels (CKCS), often leading to syringomyelia (SM). Morphometric studies have produced variable results concerning relationship between the brain parenchyma within the caudal cranial fossa (CCF) and SM. The present study assesses the effect of head position, one potential confounder. Magnetic resonance images of CKCS with CM were reviewed in extended and flexed head positions. Volumes were calculated from transverse T2-weighted brain images. Mid-sagittal images were used for measurement of cerebellar herniation and CSF space between cerebellum and brainstem. Fourteen CKCS were included into the study, seven dogs with CM and seven with CM/SM. There was no difference between the relative brain parenchyma within the CCF in extended position and flexed position, or the brain parenchyma within the rostral and middle cranial fossae proportion. Cerebellar herniation and CSF space between cerebellum and brainstem were significantly increased in the flexed position. Cerebellar herniation and CSF space differed significantly between CM and CM/SM in a flexed head position. Volumetric measurements did not vary with head position. Cerebellar herniation and CSF space between the cerebellum and the brainstem were larger in a flexed head position.     

Dryland cropping systems influence the microbial biomass and enzyme activities in a semiarid sandy soil

Indicators of soil quality, such as microbial biomass C and N (MBC, MBN) and enzyme activities (EAs), involved in C, P, N, and S cycling, as affected by dryland cropping systems under conventional (ct) and no tillage (nt) practices were evaluated for 5?years. The soil is sandy loam with an average of 16.4% clay, 67.6% sand, and 0.65?g kg^?1 OM at 0?C10?cm. The crops evaluated were rotations of grain sorghum (Sorghum bicolor L.) or forage sorghum (also called haygrazer), cotton (Gossypium hirsutum), and winter rye (Secale cereale): grain sorghum?Ccotton (Sr_g?CCt), cotton?Cwinter rye?Csorghum (Ct?CRye?CSr_g), and forage sorghum?Cwinter rye (Sr_f?CRye). The tillage treatments did not affect soil MB and EAs of C cycling (i.e., ??-glucosidase, ??-glucosaminidase, ??-galactosidase), P cycling (alkaline phosphatase, phosphodiesterase), and S cycling (arylsulfatase)??except for separation due to tillage for Sr_f?CRye and Ct?CRye?CSr_g observed in PCA plots when all EAs were evaluated together. After 3?years, rotations with a winter cover crop history (Ct?CRye?CSr_g and Sr_f?CRye) enhanced soil MBN (up to 63%) and EAs (21-37%) compared to Sr_g?CCt. After 5?years, Sr_g?CCt and Ct?CRye?CSr_g showed similar soil MBC, MBN, EAs, total carbon (TC), and organic carbon (OC). A comparison of Sr_g?CCt plots with nearby continuous cotton (Ct?CCt) research plots in the same soil revealed that it took 5?years to detect higher TC (12%), MBC (38%), and EAs (32?C36%, depending on the enzyme) under Sr_g?CCt. The significant improvements in MB and EAs found, as affected by dryland cropping systems with a history of winter cover crops and/or higher biomass return crops than cotton, can represent changes in soil OM, nutrient cycling, and C sequestration for sandy soils in the semiarid Texas High Plains region. It is significant that these soil changes occurred despite summer crop failure (2003 and 2006) and lack of winter cover crops (2006) due to lack of precipitation in certain years.     

Elasmobranch fisheries in the Arabian Seas Region: Characteristics,trade and management

The Arabian Seas Region plays an important role in the global landings and trade of sharks and rays. The United Arab Emirates (UAE) and Yemen, two countries with stark socio‐economic differences, serve as major regional trade hubs for shark and ray products and four countries (Oman, Pakistan, UAE and Yemen) supply nearly 11% of dried fin exports to Hong Kong. Yet, little information is available on the characteristics of this trade and the fisheries contributing to it. Here, we review the fisheries characteristics, trade, utilization and distribution chain of sharks and rays in 15 countries of the Arabian Seas Region based on published and grey literature, landing surveys, field observations and interviews with fishermen and traders. Although regional shark fisheries remain mostly artisanal, reported shark and ray landings represent 28% of the regional total fish production, reaching 56,074 mt in 2012 (7.3% of total world catches), with Iran, Oman, Pakistan and Yemen ranking as the primary catchers. Utilization and distribution patterns are complex, vary between landing sites and countries, and remain unmonitored. Based on widespread over‐exploitation of most teleost fisheries, current exploitation levels for most sharks and rays are potentially unsustainable. The situation is exacerbated by limited research and political will to support policy development, the incomplete nature of fisheries data, as well as insufficient regulations and enforcement. A better understanding of shark and ray fisheries will be key for regulating trade, promoting conservation and developing management initiatives to secure food security, livelihoods and biodiversity conservation in the region.