Numbers of mononchid nematodes in soils sown to cereals and grasses

The distribution of mononchid nematodes Mylonchulus sigmaturus, Mylonchulus brachyuris, Clarkus papillatus, Prionchulus punctatus and Anatonchus tridentatus found in grassland and arable soils in England were studied. Mononchid nematode populations in excess of 5% of the total soil nematode population and in biomass more than 2% of the total soil nematode population were rare. No relationship was found between numbers of mononchids and those of other soil nematodes. In soils sown to spring barley there was no difference in the total numbers of female M. sigmaturus, C. papillatus or A. tridentatus found throughout the year. Juveniles of C. papillatus were most common while those of M. sigmaturus were least common. In grass leys and arable soil P. punctatus numbers were extremely low. Neither phorate nor oxamyl applied at 1.12 kg a.i./ha in March affected mononchid numbers. Although oxamyl at 11.2 kg a.i./ha did not affect the adult female numbers, the numbers of juvenile mononchids were reduced by 38% and 50% in June and November respectively.     

Cellulose Microfibril Orientation in Rubbery Wood

The fibre length L and average helical angle of microfibrilorientation in fibres from successive growth rings in both normaland ‘rubbery’ wood of stems of apple var. Lord Lambournehave been measured. It has been shown that the normal relationship,L = A+B cot , does not hold for ‘rubbery wood’.There is a tendency for the helix to remain flat, the angle fairly constant independently of fibre length. This, togetherwith abnormalities in the lignin chemistry, causes the rubberywood to have low tensile strength and high extensibility.     

Wall Development in Apple Fruits: a Study of the Life History of a Parenchyma cell

The development of the walls of the parenchyma cells of applefruit cortex has been followed throughout two seasons underconditions which allow an assessment of wall structure as afactor involved in the keeping quality of apples. Changes inchemical compositions, in physical organization, and in cellsize have been monitored throughout.Unexpectedly rapid wallsynthesis occurs during cell extension but is followed, beforeharvest, by a period during which some pectic substances arereassimilated and in which some lability of wall componentsis indicated. There is a marked thinning of the wall at thisstage, for which subsequent secondary thickening fails to compensatefully.Differences in cell-wall structure between apples fromtrees receiving different manurial treatments are most markedduring cell extension, when cells from apples which keep wellshow symptoms consistent with a lower nitrogen level. Thesedifferences have largely disappeared by harvest, but reasonsare given to indicate that the earlier stages of fruit developmentmay have a considerable influence on potential storage life.