A NOTE ON THE ZERO-GRAZING OF BEEF CATTLE

Groups of 8 steers weighing 300–400 kg (660–880 Ib) were rotationally grazed on a ryegrass-dominant pasture for 115 days. The systems compared were zero grazing (Z), field grazing conducted at the same stocking rate (FC), and field grazing conducted at a stocking rate varied with the intention of giving the same liveweight gain per uiimal as zero grazing (FV). Mean daily liveweight gains were: Z, 0.98; FC, 0.78; FV, 0.90 kg/animal (2.2, 1.7 and 20 Ib/animal), and liveweight gains/unit area were in the ratio 100:78:85. Organic-matter intake, measured on four occasions, was, on average, Z, 6.54; FC, 6.18; FV, 687 kg/head daily (14.4, 13.6 and 15.1Ib). From these results it appears that a comparison of zero grazing and field grazing made at the same stocking rate is likely to underestimate the potential of field grazing for beef production from grass.     

The application of ultraviolet microscopy to the distribution of lignin in wood description and validity of the technique

A method has been developed for the determination of lignin distribution in the wood cell wall by ultraviolet microscopy. The method incorporates some important advances on previus applications of UV microscopy to the study of lignin distribution. Ultrathin cross-sections of wood are obtained by the sample preparation and sectioning techniques of electron microscopy. The specimens are examined in monochromatic ultraviolet light using quartz reflection optics. The microscope image is photographically recorded and the negative is subsequently subjected to densitometric analysis. Each stage of the analytical procedure has been critically assessed to determine its validity and limitations. The method is ideally suited to the study of the removal of lignin from the wood cell wall during cooking and possesses other important applications in wood technology.     

THE DISTRIBUTION OF LEAF AREA AND LIGHT INTENSITY WITHIN WHEAT CROPS DIFFERING IN ROW DIRECTION, ROW SPACING AND RATE OF SOWING; A CONTRIBUTION TO THE STUDY OF UNDERSOWING PASTURE WITH CEREALS

The distribution of leaf area and light intensity within wheat crops differing in row direction, row spacing and rate of sowing is described. Regardless of the manner of planting, 75% of the total leaf area was found within a band 31/2 in. wide, centred on the centre of the row. Light penetration within crops spaced at 14 in. was greater than within those spaced at 7 in. Light penetration within rows running N.–S. was more uniform and higher, particularly around noon, than within rows running E.-W. Within N.-S. rows the position midway between rows received the highest amount of light, but light decreased on either side until it was least beneath the rows. Within E.-W. rows at 14 in. spacing, maximum light was recorded at 101/2 in. on the southern side of a row, decreasing progressively as the row was approached.     

Non-random segregation of gene I for Fusarium resistance in the tomato

Significant deviations from the ratios expected, according to the single dominant gene hypothesis for resistance to Fusarium wilt, were found in crosses involving several susceptible and resistant tomato lines. The susceptible class was the deficient one in F₂ and F₃ populations, as well as in backcrosses in which the heterozygotic resistant F₁ served as the male parent. The reciprocal backcross, with the F₁ as the female and the homozygous susceptible as the male, gave segregations better approximating or consistent with the single gene hypothesis. Reciprocal F₁ and F₂ generations did not give any evidence of cytoplasmic effects.The results were interpreted assuming preferential fertilization of ovules by pollen grains carrying the dominant I allele for resistance.The practical implications of the phenomenon of preferential fertilization in breeding for Fusarium resistance are discussed.     

The History and Future of Forestry in the Middle Tweed

History is outlined briefly and the more recent developmentsin afforestation and the establishment of plantations are described.The effects of the factors of locality on silvicultural practiceand the problems which will subsequently arise in the futuremanagement of the forests are discussed.     

In memoriam Julius Roth

Ohne Zusammenfassung