Survival of sclerotia of Macrophomina phaseolina and Sclerotium cepivorum after drying and wetting treatments

Exposure of sclerotia of Macrophomina phaseolina to 0 and 33% relative humidity (r.h.) for 12 weeks and of Sclerotium cepivorum to 0, 33 and 55% r.h. for 20 weeks did not reduce their germinability on agar. Exposure to 78% r.h. caused high loss of germinability in M. phaseolina and complete loss in S. cepivorum. After 7-day exposures respective moisture contents of sclerotia of M. phaseolina and S. cepivorum were 1 and 2% at 0% r.h.; and 10 and 14% at 78% r.h. M. phaseolina sclerotia held at 0% and 33% r.h. in desiccators for several times up to 12 days did not decrease in subsequent survivability in moist soil, unlike sclerotia held at 78% r.h. for 4 days.More sclerotia of M. phaseolina were colonized by fungi and Streptomyces spp. on alkaline soil than on acid soil. On alkaline soil twice as many sclerotia were colonized after exposure to 0% r.h. as after exposure to 33, 55 and 78% r.h. Colonization of S. cepivorum sclerotia was as high on acid as on alkaline soil and 3 times as high on sclerotia treated at 0% r.h. as on those treated at higher r.h. Attempts to ascertain the effects of colonization on sclerotial viability were unsuccessful. Incubation of sclerotia of M. phaseolina in moist Rumsford sandy loam (50% m.h.c.) for 20 weeks reduced survivability by 43%. At room temperature, alternate drying and wetting of soil containing sclerotia did not appreciably affect survivability of either pathogen. Survivability of S. cepivorum sclerotia was highest when the sclerotia were incubated in air-dried soil (2–3% m.h.c.) for 20 weeks.Incidence of white rot on onion seedlings transplanted to S. cepivorum-infested soil was higher in soil that had been air-dried for 20 weeks than in soil that had been alternately wetted and dried. Sclerotia that were exposed to 0% r.h. for 7 days before soil incubation produced little white rot.     

Analysis of fat-soluble vitamins. XVI. Antirachitic activity of 5,6-trans-vitamin D3 alone and in the presence of 5,6-cis-vitamin D3 resin, using chick bioassays.

Two biological assays were conducted in which the antirachitic activity in chicks of 5,6-trans-vitamin D3 added to feed is compared with that of 5,6-cis-vitamin D3. On the basis of the results obtained it is concluded that the relative potency of the trans isomer is, at the most, 5% and that the antirachitic activity of the trans isomer is not markedly enhanced (an increase to a relative potency of 16%, at the most) if the cis isomer is also included in the diet. The results are not conclusive on the inhibition or lack of inhibition of the antirachitic activity of 5,6-cis-vitamin D3 by the presence of 5,6-trans-vitamin D3 in the feed.     

The effect of urea on the voluntary intake by calves of silages preserved with formaldehyde and formic acid

Perennial ryegrass cv. S23 was preserved by fermentation (C), or with the addition of 8.7 1 formalin (35% w/w formaldehyde) per t fresh herbage (F) or of 9.0 1 equal mixture (by vol.) of formalin and formic acid (85% w/w solution) per t fresh herbage (FF). These three silages comprised the treatments in a three-period, crossover design in which urea (u) was given at the rate of 20 g per kg dietary DM to half the animals. Twelve calves were allocated to the treatment sequences when they were approximately 12 weeks of age from within groups which had previously received diets with or without urea. Calves ate significantly (P< 0.001) less of silages F or FF than of silage C when each was offered alone, but when urea was given, intakes of silages F and FF were significantly (P < 0.001) increased such that the intakes of all three silages with urea were similar (23.6, 19.6, 19.3, 24.2, 24.2, 24.7 ± 0.51 g DM per kg LW for C, F, FF, Cu, Fu and FFu, respectively). Significantly (P<0.01) more of the DM in silage C was digested than in F or FF and the addition of urea significantly (P<0.05) increased the digestibility of DM from silage FF only (73.8, 71.3, 69.8, 74.6, 70.7, 72.5 ± 0.72% for C, F, FF, Cu, Fu and FFu, respectively). When the silages were given alone, calves spent longer eating and ruminating per kg DM ingested with F or FF than with C. The time spent on F and FF was significantly (P<0.01) reduced by the addition of urea (303, 388, 411, 297, 299, 290 ± 18.9 min per kg DM ingested for C, F, FF, Cu and Fu and FFu, respectively). The results presented suggest that urea partially alleviated the reduction in voluntary intake by calves given herbage preserved using formalin, but the mode of action was not clear.     

Nitrogen fixation by white clover in hill pasture

An experiment is described in which the amount of nitrogen fixed by the white clover component of a surface-sown hill sward was determined using small quantities of ¹⁵N-labelled ammonium sulphate. Between 11 July and 22 August 1974 25 kg ha^?1 N was fixed. No evidence of a transfer of N from clover to the associated perennial ryegrass was detectable over this period although the N content of the grass growing with the clover was higher. The relative advantages of the isotope technique and the acetylene reduction assay are discussed.     

Silage and milk production: a comparison between four rates of groundnut cake supplementation of silage of high digestibility

Grass silage made in late May from S24 perennial ryegrass was offered to twelve Ayrshire cows in a 16-week feeding experiment. The silage had a DM content of 25.3%, a pH of 3.91, and contained 16.8% CP and 68.4% digestible organic matter in the DM. The silage was fed ad libitum and was the sole feed in the control treatment. In the other three treatments the silage was supplemented with a cube offered at rates of 0.8, 1.4 and 2.0 kg per 10 kg milk. The cube contained 82.2% groundnut, plus molasses and minerals, and had 37.9% CP in the DM. The daily intake of silage DM was 11.4 kg per cow on average over the four treatments which did not differ significantly. The mean daily milk yields were 14.8 kg per cow in the control treatment, and 16.5, 18.2 and 18.4 kg in the 0.8, 1.4 and 2.0 kg supplement treatments respectively. The SNF, CP and lactose contents of the milk were Wghest on the 1.4 kg supplement treatment. It is concluded that with a high digestibility silage, there is little evidence to support the feeding of more than 1.4 kg of high-protein cubes per 10 kg milk in the declining phase of lactation.     

INTERACTIONS BETWEEN FIRST AND SECOND APPLICATIONS OF FERTILIZER NITROGEN AND IMPLICATIONS IN EFFICIENCY OF NITROGEN USE

DM yield and N uptake data are presented from primary growth and two successive regrowths of perennial ryegrass treated with combinations of three N treatments for the primary growth viz. 0, 50 and 100 kg N/ha (PN) and four N treatments applied for the second growths, viz. 0, 33, 66 and 100 kg N/ha (SN). Primary growth gave a response of 24·2 kg DM/kg applied N to PN50 with only a further l±0 kg DM/kg applied N from the second PN increment. A significant interaction between PN and SN treatments was shown in second growth. The residual DM response to PN was highest at SN0 and reduced as the level of SN was raised. Substantially greater residual responses to PN treatments were shown in the third growth. Third growth DM responses to SN treatments were high. High apparent recovery of fertilizer N reached 111% of primary N where SN66 followed PN50. High available soil N is partly responsible for both high apparent recovery of N and high DM response. The latter appears to be associated with inclusion of growths given no fertilizer N so that the full residual effects of fertilizer N and ‘priming’ of available soil N can be realised.     

Enzyme activity in soils at subzero temperatures

Urease activity, phosphatase activity, and sulfatase activity were detected in soils at ?10 and ?20°C. The occurrence of enzyme activity in soils at subzero temperatures is attributed to enzyme-substrate interaction in unfrozen water at the surfaces of soil particles. Support for this explanation was obtained from experiments showing that hydrolysis of urea by jackbean urease occurs at ?10 or ?20°C in the presence, but not in the absence, of clay minerals or autoclaved soils. No enzyme activity could be detected in soils at ?30°C.     

The identification of grey mullet species by disc electrophoresis

Electrophoresis was carried out on the water-soluble muscle protein (myogen) of six grey mullets (Mugilidae), caught off the Mediterranean coast of Israel. With the obtained electropherograms it was possible to identify the adults and juveniles of five species of grey mullet. A tentative key for species determination based on the myogen electrophoretic pattern of five species (Liza ramada (Risso, 1826), L. aurata (Risso, 1810), L. provensalis (Risso, 1826), L. saliens (Risso, 1810) and Mugil cephalus (Linnaeus, 1758)) is given. Of the sixth species, Oedalechilus labeo (Cuvier, 1829), only one small adult and six juvenile specimens were obtained.A fast moving band occurred in the pattern of all juveniles of the investigated species. This fraction decreased during growth of all species, it became faint in adults of L. saliens, L. provensalis and L. ramada and was not observed in adult L. aurata and M. cephalus.