The role of autotoxins from root residues of the previous crop in the replant disease of asparagus

Replant disease is a common phenomenon in asparagus growing in the Netherlands. It is distinct from the decline phenomenon reported from many other asparagus producing area’s. The involvement of autotoxins from root residues of former asparagus crops was evaluated. Residues of aspar agus roots decompose extremely slowly. At two locations, each with fields where asparagus production was terminated 1 and 10 years before, biomass of root residues was 4180 and 11060 kg dw ha^?1 after 1 year and 420 and 1140 kg dw ha^?1 after 10 years.Although 10-year-old residues were for the greater part decomposed, crude aqueous extracts inhibited root growth of asparagus seedlings significantly and even more of garden cress. In root observation boxes with field soil mixed with non-sterilized or sterilized asparagus root fragments, growth of secondary roots was inhibited. Non-sterilized strawberry roots did not inhibit root growth, suggesting that effects of organic matter were not involved. In a pot experiment, sterilized asparagus root fragments inhibited root growth when added at a rate of 20 g1^?1, but not a 2 g1^?1 Addition of non-sterilized root fragments strongly inhibited root growth at both levels. This was probably due to simultaneous infection byFusarium oxysporum present in these residues. When an asparagus field is replanted, the amount of root residues left behind in soil after termination of the crop in the previous season is about 2 g dw 1^?1, that corresponds to approx. 11000 kg dw ha^?1. This level is too low for considering direct growth inhibition by autotoxins as a major factor. Their possible indirect effects are briefly discussed.     

The biochemical basis of resistance of potato to soft rot bacteria

Evidence is presented that a number of mechanisms are involved in the resistance of commercial cultivars of potato to soft rottingErwinia spp. These include phytoalexins, phenolics, cell wall modification, and possibly proteins. The role of elicitor-active oligogalacturonides, which are released from plant cell walls by pectic enzymes, is discussed.     

Interactions among herbivores,microbial insecticides and crop plants

Knowledge of the interactions among lepidopterous insects, microbial insecticides and plants is either lacking or incomplete. In some of the interactions, plant allelochemicals antagonized the insecticidal activity of the microbe by means of feeding reduction. In others, microbe activity was enhanced either by causing insect toxicity or by a potentiation of the crystal protein. Nutritional evaluations of the interactions amongHeliothis virescens. Bacillus thuringiensis crystal protein and tannin showed that microbe toxicity in the larva was antagonized by this phytochemical.     

Nutrition and Health of Dogs and Cats: Evolution of Petfood

Maintaining the health of dogs and cats by feeding wholesome nutritional diets is becoming an important component of responsible pet ownership. Pet owners now seek a long and healthy life for their pet and look to nutrition, as well as to veterinary medicine, to provide such support. Quality of life, measured in terms of reduced incidence of diseases and the ability to maintain an active life, would appear to be able to be enhanced by appropriate nutrition and nutraceutical supplementation. As a consequence numerous improvements in companion animal nutrition have resulted in development of a wide array of foods that provide complete and balanced nutrition. As a result emphasis also has to be placed on product safety and quality parameters, in connection with traceability. The origin of products, including product characteristics and properties, processing conditions and further handling throughout the period chain, is becoming ever increasingly an issue for collective chain management.     

Effect of dietary inclusion of date seed (<Emphasis Type="Italic">Phoenix dactylifera</Emphasis> L.) on intake,digestibility, milk production,and milk fatty acid profile of Holstein dairy cows

The objective of this experiment was to investigate the influence of ground date seed (GDS) on intake, digestibility, and milk yield and milk fatty acid (FA) composition of lactating Holstein cows. The experimental design was a 4?×?4 replicated Latin square with eight lactating dairy cows with an average milk production of 35.5?±?1.5 kg and 75?±?5 days in milk (DIM). Dairy cows were fed one of the four treatments contained 0, 2, 4, and 6% of diet dry matter (DM) GDS in replacement of wheat bran. All diets contained the same amount of forages (alfalfa hay and corn silage). Dietary treatments had no effect on DM intake (DMI), total tract apparent digestibility, milk yield, and milk composition. Increasing GDS linearly decreased concentration of C13:0 and increased cis-9 C14:1 and trans-11 C18:1 (vaccenic acid) (P?<?0.05). A linear tendency for more C16:1 content in milk fat was observed with increasing GDS (P?=?0.06). Feeding GDS resulted in a linear decrease (P?<?0.01) in saturated FA (SFA) but increased milk fat monounsaturated FA (MUFA) and trans FA (TFA) (P?<?0.05). Therefore, low levels of GDS (up to 6%) in the diet of Holstein dairy cows can beneficially modify milk FA composition without any adverse effects on intake, digestibility, and milk yield.     

Genetic evaluation of growth in farmers’ flocks of Madras Red sheep under long-term selection in a group breeding scheme

The Network Project on Sheep Improvement (NWPSI)–Madras Red field unit is a group breeding scheme involving 198 farmers’ flocks of Madras Red sheep in which selection for growth traits and rotation of rams have been practised for over two decades. Growth data collected from these flocks were used to evaluate the performance and understand the direct and expected responses to selection based on genetic parameters. The body weight at birth (BW), weaning weight (WW), 6-month weight (6W), 9-month weight (9W), 12-month weight (YW), pre-weaning average daily gain (ADG1, birth to 3 months), post-weaning ADG2 (3–6 months), ADG3 (6–9 months), ADG4 (9–12 months) and ADG5 (3–12 months) were 2.67, 10.05, 14.56, 18.36, 21.36, 80.13, 49.05, 43.00, 34.21 and 41.18 g, respectively. Univariate analyses were carried out using animal and sire models to estimate variance components. Heritability obtained from animal model for BW was 0.36 and the values for other body weight traits were almost unity. Heritability estimate for pre-weaning ADG1 was 0.31. Very high genetic variability was observed in spite of long-term selection and this sustenance of variability is one of the main advantages of a group breeding scheme, combining several flocks of smaller size. An increasing genetic and phenotypic trend was noticed for almost all the traits studied. The expected responses calculated based on genetic parameters also indicated scope for improvement.