ALBERT

Notes: Abstract. The authors examine the isotopic composition of leaf water, at natural abundance levels, as influenced by transpiration rate. The isotopic composition of water of wheat leaves (Triticum aestivum L. var. Aroona) was followed while their transpiration rate adjusted to ‘steady-state’ environmental conditions. Leaf diffusive resistance was modified by short-term salt treatment and by plant culture in either nutrient solution, free-draining sand, or vermiculite. Resultant changes in 18O and 2H in leaf water are described and fitted to the model of Leaney et al. (1985). The treatments with lower transpiration rates were found to have a greater fraction of their leaf water equilibrated with water vapour in the atmosphere. Comparable results were obtained with both 18O and 2H, with some differences being interpreted in terms of turbulence in the vapour diffusion path. The fraction of the leaf water equilibrated with the atmosphere varied between leaves of different ages. However, this may have been due to their different positions in the canopy.

Notes: Two fitness components, development rate and egg size, were examined in six hatchery strains of rainbow trout, Oncorhynchus mykiss (syn. Salmo gairdneri Richardson), with different amounts of enzyme heterozygosity. The average expected heterozygosities per strain ranged from 4 to 8%, based upon an electrophoretic analysis of the protein products of 42 loci. Strains with higher heterozygosities had faster development rates, as measured by hatching time, than strains with lower heterozygosity. Concordance between hatching time and another measure of development rate, degree of yolk-sac resorption, suggests that hatching time is a valid measure of embryonic development rate in salmonid fishes. Earlier-hatching embryos were longer and heavier at the time of yolk-sac resorption than later-hatching fish. Females from more-heterozygous strains also had a tendency to have larger eggs. These data suggest that genetic variation is an important biological resource to be conserved in hatchery stocks.

Notes: High temperature has been implicated as the major factor responsible for dwarfing of selected apple (Malus domestica Borkh.) trees of a hybrid population of cv. Goldspur Delicious x cv. Redspur Delicious. Dwarf plants grew only 2.2 cm in 63 days under a ramped temperature regime (night 15°C, day ramped up to 38°C, held for 2 h and ramped down to 15°C—14 h daylength), whereas semi-dwarf plants grew 26.3 cm. At a constant 27°C (14 h daylength), both dwarf and semi-dwarf plants grew 26.3 cm. At a constant 27°C (14 h daylength), both dwarf and semi-dwarf plants grew nearly 50 cm. The gibberellin biosynthesis inhibitor, paclobutrazol, retarded growth of semi-dwarf plants in both ramped and constant environments and dwarf plants in the constant 27°C environment. It did not further reduce the size of dwarf plants growing under the ramped regime. Gibberellin (GA3) treatment reversed the inhibition of growth caused by paclobutrazol for all plants except it did not restore growth of dwarf plants in the ramped environment. These data suggest that neither pacobutrazoltreated nor untreated dwarf plants growing in the ramped environment (or in the orchard during hot summer months) are able to respond to GA3. In constrast, GA3 was utilized by the paclobutrazol-inhibited dwarf plants growing at constant 27°C, enabling shoot elongation to take place. It appears that high temperature may have caused alterations in GA target tissues in dwarf plants so that they no longer had the capacity to respond to GA.

Notes: The role of environment on the dwarfing (short internode) phenomenon of apple (Malus domestisca Borkh.) was investi gated and defined in controlled environmental chambers. Orchard-grown very dwarf, dwarf and semi-dwarf trees obtained by natural sibcrossing of spur-type cv. Golden Delicious and cv. Delicious, as well as standard cv. Golden Delicious, were propagated via in vitro techniques. Growth was rapid and none of the 4 types exhibited dwarf-like characteristics when grown at constant 27°C with 12, 14 or 16 h daylengths. Standard and very dwarf plants grew at nearly the same rate at constant 30°C, whereas growth nearly ceased on both types at constant 35°C after 7 days. Dwarf and very dwarf plants responded differently from standard and semi-dwarf plants when grown under alternating (ramped) night/day temperatures (15 or 20°C night ramped up to a daytime maximum over 8 h of 23, 28, 33 or 38°C, held for 2 h and then ramped down over 5 h to the night temperature). As the night/maximum day temperature differentia) increased from 0 to 23° under the ramping environments, growth of dwarf plants decreased markedly as compared to standard plants. When the same night/maximum day temperature differential occurred, the effect on decreasing shoot length was greater at the higher (20°C) night temperature. Increasing maximum day temperatures under the ramped environment also reduced leaf area plant−1 but did not markedly affect leaf number, resulting in short internodes. When a period of constant temperature was followed by ramped temperatures or vice versa, the sequence of constant vs ramped environments made little difference in the final growth of the 4 plant types. The data point to high temperature as the major factor for causing dwarfing of the sensitive plant types. Increasing the differential between night and maximum day temperature resulted in short internode. dwarf plants with small leaves similar to orchard-grown dwarf trees.

Notes: Data are few on concentrations of nitrogen (N) in the cell wall and lignocellulose (neutral- and acid-detergent fibre (NDF and ADF), respectively) of herbage. Herbage N can be partitioned into neutral- and acid-detergent soluble and insoluble N to crudely estimate rapidly degradable (N soluble in neutral detergent), slowly degradable (neutral-detergent fibre N (NDFN) minus acid-detergent fibre N (ADFN), herein termed available fibre N (AFN)), and indigestible N (ADFN) in the rumen. Our objective was to examine the effects of herbage species, maturity stage, and plant part on N in the NDF and ADF of lucerne (Medicago sativa L.), red clover (Trifolium pratense L.), timothy (Phleum pratense L.), and smooth bromegrass (Bromus inermis Leyss.). Herbage was harvested at four 2-week intervals during spring of 1984 and 1985. Leaves, stems and total herbage were analysed for total N, and N in NDF and ADF. Concentrations of N in ADF in leaves, stems, and total herbage of lucerne and clover were twice that of grass ADF. This may be due to greater lignin concentrations generally reported in legumes. Concentrations of NDFN in leaves of lucerne, clover, timothy, and bromegrass were 9–8, 26.4, 8.6, and 6.4 g kg−1 of NDF, respectively, averaged over harvests and years, whereas stem concentrations were 4.2, 4.6, 32, and 2.4 g kg−1 of NDF, respectively. Leaf concentrations of ADFN in lucerne, clover, timothy, and bromegrass were 4.6, 5.3, 20, and 1.6 g kg−1 of ADF, respectively, averaged over harvests and years, whereas stem concentrations were 3.4, 33, 14, and 14 g kg-’of ADF, respectively. As a proportion of the total N, NDFN and ADFN increased with plant maturity in leaves, stems, and herbage. In stems, 49% of NDFN was ADFN, whereas in leaves only 21% of the NDFN was ADFN. The larger portion of ADFN in stems probably reflects the larger proportion of lignified xylem and other structural tissues, which have a greater proportion of lignified secondary cell walls, whereas the greater proportion of NDFN in leaves may mirror the greater amount of mesophyll cells with primary cell walls. More than 80% of the total N in leaves, stems, and herbage was in the cell solubles, which may be rapidly ruminally degradable.

Notes: Humpback whales sing long, complex songs on their wintering grounds. On 25 August 1979 and 3 September 1981, we made recordings of humpback whale songs in southeastern Alaska, showing that humpback whales also sing on the summer feeding grounds. Both these Alaskan samples are songs in that they are repeating cyclical sound patterns and follow the known structure for humpback whale song. The Alaskan songs contain all the same material sung in the same order as that heard off Mexico and Hawaii in the surrounding wintering seasons. However, song, theme and some phrase durations are abbreviated in the Alaskan songs. The recording of these two songs represents the full sample of song recorded from 155 days over five years of attempting to record humpback whale song in Alaskan waters.