Differences in Wheat Cultivar Response to N Supply. I: Differences in Grain Yield Formation

Two-year field trials with winter wheat cultivars Batis and Toronto were conducted in Southern Bavaria, Germany, to investigate the possible causes of cultivar differences in response to N supply varying in total amount and time of application. Cultivar-related differences in grain yields were observed in treatments with low and medium N supply. High doses of N supply resulted in grain yield adjustment or grain yield advantage for cv. Toronto. The results of this study revealed a consistent, genotypic pattern in response to N fertilization in spite of strong seasonal effects. Systematic modifications in canopy growth rates in response to N supply were of particular relevance and a main factor for differences in tillering intensity resulting in modified stand densities. In the present study, cultivar differences in spike development and interactions with N supply related more to abortion than to initiation processes for number of spikelets and number of flowers per spikelet. High grain density (grains per m²) of cv. Toronto was evident during reproduction stages even under conditions of medium N supply. However, decreased growth rates during the later part of grain filling in combination with low 1000 grain weight, which was barely modified by N fertilization, allowed only partial utilization of this potential. It is assumed that sink limitations were of particular relevance for grain yield development in cv. Toronto, while cv. Batis combined a less intense response to N supply with more stability in the development of grain yield components.     

Relationship between blood iron parameters and trichinellosis in swine

Reduced levels of total iron binding capacity and unsaturated iron binding capacity were observed in the blood of trichinous and iron-injected trichinous pigs. No change was observed in their serum iron and saturation concentration levels. Also, reduced iron concentration levels were observed in the livers of trichinous pigs, while increased iron concentration levels were observed in the spleens of trichinous pigs and the livers and spleens of iron-injected pigs. No difference was found with regard to weight gains, number of larvae per gram of tissues, or histologic characteristics of 'nurse cells'.     

Seasonal mixing and catastrophic degassing in tropical lakes, cameroon, west Africa

Lethal gas releases from Lakes Nyos and Monoun in Cameroon seem to be more lacustrine than volcanic in origin. Both of these events occurred in August and were only 2 years apart. Data show that the period of deepest mixing and lake turnover also occurs during late summer in this region of tropical Africa. In addition, recent trends of decreases in both air temperatures and effective insolation relative to long-term means suggest that weakening of stratification, coupled with a predictable seasonal interval of reduced stability in August, may be responsible for the timing of these events.     

Growth and the composition and transport of carbohydrate in compatible and incompatible peach/plum grafts

The growth of scions and rootstocks of compatible (Prunus persica L. Batsch cv. Springtime/Prunus cerasifera L. Ehrh. cv. myrobolan P2032) and incompatible (Prunus persica L. Batsch cv. Springtime/Prunus cerasifera L. Ehrh. cv. myrobolan P18) peach/plum grafts were compared. The composition of soluble carbohydrates in phloem and cortical tissues of both peach/plum grafts and ungrafted plums and the translocation of these compounds across the union of grafted plants were examined. Sorbitol and sucrose were the dominant sugars in the phloem and cortical tissues of plum. A cyanogenic glycoside, prunasin, was present in peach tissues in amounts equivalent to those of sorbitol or sucrose, whereas only small amounts of prunasin were detected in plum tissues. The concentration of prunasin was significantly higher in the phloem of the P18 rootstock of the incompatible graft. Sorbitol was the only sugar significantly depleted in rootstock tissues of the incompatible graft when the first foliar symptoms of graft incompatibility became evident. Translocation studies with 1-(14)C-deoxyglucose showed that the relative distribution of radioactivity across the graft union was similar in both compatible and incompatible grafts. However, the total amount of radioactivity translocated across the incompatible graft was less than one-third of that translocated across the compatible graft. The results are consistent with the hypothesis of a progressive poisoning of the root system in the incompatible graft by a compound synthesized in peach foliage. The role of prunasin as a possible candidate is discussed.     

Solar neutrinos: questions and hypotheses

The "solar neutrino puzzle" has been a challenge for almost 20 years, posing broad and fundamental questions about astrophysics and neutrino properties. This article sketches some of the ideas that have been put forward to solve the problem. These ideas can be grouped into two main classes: those involving changes in the standard solar model or in the basic nuclear reaction data, and those that attribute the puzzle to as yet unobserved properties of the neutrinos.     

Arsenic poisoning in dairy cattle from naturally occurring arsenic pyrites

An outbreak of arsenic poisoning occurred in which most of a 200 cow dairy herd were affected and six died. The source of the arsenic was naturally occurring arsenic pyrites from the Waiotapu Stream, near Rotorua. Arsenic levels in the nearby soil were as high as 6618 ppm. There was little evidence to suggest that treatment affected the course of the disease. Haematology was of little use in diagnosis, post-mortem signs were not always consistent and persistence of the element in the liver appeared short. Control of further outbreaks have been based on practical measures to minimise the intake of contaminated soil and free laying water by the stock.     

Some field observations on the antibody response to avian infectious bronchitis on Auckland layer farms

Layer flocks on four Auckland poultry farms were monitored monthly for Infectious Bronchitis (IB) antibody levels, using the haemagglutination inhibition test. The same birds were bled each month and antibody levels compared with egg production. The results showed that IB vaccination at 4(1/2) and 14(1/2) weeks using the live, attenuated, New Zealand A strain virus, protected layers from IB infection on a farm with good management techniques but vaccination on another commercial farm gave less then ideal protection due possibly to intercurrent disease. Also antibody levels in naturally infected layers responded more vigorously when exposed to the field strain, compared with the response in vaccinated birds.