Morphological studies of Asian rice and its related wild species and the recognition of a new Australian taxon

In order to clarify the taxonomy and the interrelationships among Asiatic cultivated rice, Oryza sativa , and its related wild species ( O. rufipogon, O. nivara and O . barthii ), 41 morphological characters were examined. Numerical taxonomic methods were used to analyse the data and to illustrate species relationships.
Distinctive differences among the materials studied suggest the retention of O. rufipogoon, O. nivara and O . sativa as three distinct species. The origin of O. sativa from O. nivara through domestication is discussed. An annual wild taxon from Australia, which had been classified as a form of O. nivara , is shown to be distinct from typical O. nivnra and is raised to specific rank. This species has been named O. meridionalis Ng.     

Investigating the potential impacts of climate change on a marine turtle population

Recent increases in global temperatures have affected the phenology and survival of many species of plants and animals. We investigated a case study of the effects of potential climate change on a thermally sensitive species, the loggerhead sea turtle, at a breeding location at the northerly extent of the range of regular nesting in the United States. In addition to the physical limits imposed by temperature on this ectothermic species, sea turtle primary sex ratio is determined by the temperature experienced by eggs during the middle third of incubation. We recorded sand temperatures and used historical air temperatures (ATs) at Bald Head Island, NC, to examine past and predict future sex ratios under scenarios of warming. There were no significant temporal trends in primary sex ratio evident in recent years and estimated mean annual sex ratio was 58% female. Similarly, there were no temporal trends in phenology but earlier nesting and longer nesting seasons were correlated with warmer sea surface temperature. We modelled the effects of incremental increases in mean AT of up to 7.5°C, the maximum predicted increase under modelled scenarios, which would lead to 100% female hatchling production and lethally high incubation temperatures, causing reduction in hatchling production. Populations of turtles in more southern parts of the United States are currently highly female biased and are likely to become ultra‐biased with as little as 1°C of warming and experience extreme levels of mortality if warming exceeds 3°C. The lack of a demonstrable increase in AT in North Carolina in recent decades coupled with primary sex ratios that are not highly biased means that the male offspring from North Carolina could play an increasingly important role in the future viability of the loggerhead turtle in the Western Atlantic.     

Immunological Studies on the Tuber-bearing Solanums III. Variability within S. bulbocastanum and its hybrids with species in series Pinnatisecta

It was shown in the previous paper of this series that the Mexicanspecies Solanum bulbocastanum, S. cardiophyllum subsp. cardiophyllumand subsp. ehrenbergii, S. michoacanum and S. pinnatisectummay be differentiated to some extent by the double diffusiontechnique, and more fully by immuno-electrophoretic analysis.Above all, the relative electrophoretic mobilities of certaincomponents, as expressed by the index have been found to be very constant for each species, with the apparent exception of S. bulbocastanum. A detailed investigation of S. bulbocastanum has now shown thatalthough the many clones of this species appeared similar whenexamined by double diffusion, differences were exposed by immuno-electrophoreticanalysis. In particular, the values fell into two discrete groups, 0.15 to 0.23 and 0.30 to 0.46. Theplants in these groups had been collected from Oaxaca and Guatemala,and from Central Mexico, respectively. Most of the former grouphad been identified as S. bulbocastanum subsp. partitum, andall the latter group as subsp. bulbocastanum and subsp. dolichophyllum.Not only was the wide variation in values of index resolved into two meaningful groups, but it was also found thatall lines within any one collection had almost identical values. The index value for S. cardiophyllum subsp.cardiophyllum is 1.0, and for subsp. ehrenbergii is 0.7. The F₁ hybrids between either ofthese subspecies and S. bulbocastanum had fairly uniform valuesclose to the calculated means of the parental values. The shapesof the leaves of these hybrids were also uniform and more orless intermediate between those of the parents in each case. The F₂ hybrids between S. bulbocastanum and S. pinnatisectum,and also the triple hybrids between these two species and eitherS. cardiophyllum or S. michoacanum, showed a wide range of valuesof index and of leaf shapes, with partial segregation towards the parental types. The serological andmorphological characters segregated independently. S. X sambucinum was found to have a wide variation in serologicaland morphological characters. This variation was consistentwith the theory that S. X sambucinum is a natural hybrid betweenS. pinnatisectum and S. cardiophyllum subsp. ehrenbergii. Within the groups of species investigated, the relative electrophoreticmobilities of certain antigens as displayed by immuno-electrophoreticanalysis were found to vary significantly in different species,in different subspecies of the same species, and in specieshybrids.     

Assessment of phosphine fumigation as a plant quarantine measure against Spodoptera littoralis

In laboratory tests first instar larvae of Spodoptera littoralis were killed by phosphine fumigations of 24 and 48 h at a concentration x time product (CTP) of 36 mg h/1. Eggs aged 1–2 days were, however, tolerant to phosphine at a CTP of 144 mg h/1 and this CTP caused severe damage to chrysanthemum cuttings (cv. Freedom). When eggs aged < 1 day and 1–2 days old were preconditioned at 20 ^oC for 72 h before phosphine fumigation, complete mortality occurred at CTPs at and above 36 mg h/1. Preconditioning for 48 h at 20 ^oC and for 48 and 72 h at 15 ^oC did not produce 100% mortality at a CTP of 288 mg h/1. It was suggested that eggs of S. littoralis pass through a phase of tolerance to phosphine which at 20 ^oC lasts about 4 days after oviposition.
There was no indication that phosphine was toxic to chrysanthemum cuttings (cv. Pollyanne) at concentrations of 0–75 mg/1 (CTPs of 18 and 36 mg h/1). Storage at 15 ^oC was not damaging to cuttings but at 20 ^oC some damage became apparent.     

Soil temperature affects carbon allocation within arbuscular mycorrhizal networks and carbon transport from plant to fungus

How soil carbon balance will be affected by plant–mycorrhizal interactions under future climate scenarios remains a significant unknown in our ability to forecast ecosystem carbon storage and fluxes. We examined the effects of soil temperature (14, 20, 26 °C) on the structure and extent of a multispecies community of arbuscular mycorrhizal (AM) fungi associated with Plantago lanceolata. To isolate fungi from roots, we used a mesh‐divided pot system with separate hyphal compartments near and away from the plant. A ¹³C pulse label was then used to trace the flow of recently fixed photosynthate from plants into belowground pools and respiration. Temperature significantly altered the structure and allocation of the AM hyphal network, with a switch from more vesicles (storage) in cooled soils to more extensive extraradical hyphal networks (growth) in warmed soils. As soil temperature increased, we also observed an increase in the speed at which plant photosynthate was transferred to and respired by roots and AM fungi coupled with an increase in the amount of carbon respired per unit hyphal length. These differences were largely independent of plant size and rates of photosynthesis. In a warmer world, we would therefore expect more carbon losses to the atmosphere from AM fungal respiration, which are unlikely to be balanced by increased growth of AM fungal hyphae.     

A STUDY OF THE BIOLOGY AND CONTROL OF ANISOPUS FENESTRALIS (SCOPOLI, 1763), A FLY ASSOCIATED WITH SEWAGE FILTERS

In work on the control of the sewage fly Anisopus fenestralis (Scopoli, 1763), it was shown that the larval phase was considerably lengthened by limiting the food supplied. The effects of food supply and temperature are considered in relation to the incidence of the adult fly in the filters. The assessment of the fly population of sewage filters by tray traps, as previously used by other workers, was investigated. Both light and temperature were found to affect the number of A. fenestralis entering the trays: it is concluded that although the trays do not accurately assess the A. fenestralis population of a bed, nor measure the rate of emergence from the bed, they are of value in assessing the relative effect of different control measures. In the filters the period of maximum abundance was during the spring, followed by a period of reduced numbers throughout the summer, with a recovery in the autumn giving relatively high numbers throughout the winter. Emergence of A. fenestralis from the filters is influenced by climatic factors, especially temperature and light; a diurnal variation in the rate of emergence was also observed. Because of this effect of temperature on emergence, the flies were only present above the filters in the warmer periods of the year; and because of the reduced numbers in the filters in the summer, the flies were only abundant above the beds during the spring and early summer and in the autumn. BHC applied as a water-dispersible powder was more effective than in the form of an emulsion. It was also most effective when used against the larval phase.