摘要:

A crop physiologist's approach to some problems of grassland research, with particular reference to terminology and the sown sward.

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1966.tb00457.x

出版商:Blackwell Publishing Ltd    

年代:1966

数据来源: WILEY

摘要:

The effect of cocksfoot streak virus (CSV) onDactylis glomerataL. and barley yellowdwarf virus (BYDV) onLolium perenneL. was investigated under both single‐plant and simulated‐sward conditions. The effect of cocksfoot mottle (CFMV) was examined on single plants. CFMV was lethal, and in conditions of inter‐plant competition CSV was semi‐lethal and BYDV was non‐lethal. When the virus was lethal, a considerable lag‐phase was observed between mortality and complete compensation in yield. When the virus was non‐lethal, plant growth was restricted, either horizontally (CSV) or vertically (BYDV). In mixed, healthy and infected plant populations healthy individuals compensated only for reductions in lateral growth.CSV infection transformed plants of a pasture variety into ‘hay’ types and BYDV infection transformed plants of a hay variety into ‘pasture’ types. CSV increased the plant's aggressiveness in hay conditions, but reduced its ability to withstand frequent defoliation. Conversely, BYDV increased the plant's aggressiveness in pasture conditions, but reduced it in hay conditions. Compensation from healthy plants occurred only in CSV‐infected swards subjected to frequent defoliation. Some possible reasons for the absence of compensation in other t

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1966.tb00458.x

出版商:Blackwell Publishing Ltd    

年代:1966

数据来源: WILEY

摘要:

Sorghum almum, Digitaria decumbensandPanicum maximumwere fed in fresh, frozen (−20 C) or dried (85° C) form to 21 wethers in metabolism cages. Neither freezing nor drying had a significant (P>0·05) effect on voluntary intake, dry‐matter digestibility or organic‐matter digestibility. Drying depressed the apparent digestibility of the nitrogen in all grasses but only in the case ofD. decumbenswas this significant (P<0·05). Freezing also depressed the apparent digestibility of N while both freezing and drying reduced N retention, compared with the fresh feed. None of these differences was significant.Freezing and drying are thus methods of pasture preservation that can be used to study the intake and dry‐matter digestibility of tropical pastures, but both methods may introduce bias into the measurement of N digestibility and

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1966.tb00459.x

出版商:Blackwell Publishing Ltd    

年代:1966

数据来源: WILEY

摘要:

An experiment is described in which nitrogen was applied in relation to the physiological stage of development in cocksfoot grown for seed. All applications of N increased the yield of seed, but applying all the N during the phase of autumnal tillering was less effective than applying it at stages of development in spring (beginning of vernal growth, initiation of inflorescences, complete differentiation of inflorescences), or in autumn and spring, because of a decrease in the number of tillers which survived to flower in the following year. Differences due to the stage of development at which N was applied in spring were small. Primary effects of N were to increase the number of tillers and ears per plant, and to accelerate the rate of development of inflorescences; in addition, N advanced the date of initiation of inflorescences without similarly advancing the date of complete differentiation of inflorescences. It is concluded that a long period between the initiation and complete differentiation of the inflorescence is conducive to high yields of seed.

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1966.tb00460.x

出版商:Blackwell Publishing Ltd    

年代:1966

数据来源: WILEY

摘要:

Irrigated lucerne/grass mixtures were treated with annual applications of N‐P fertilizers to determine the extent of control of lucerne domination. Eighty pounds of N with or without associated P sustained the grass components at an acceptable level and increased yields, which were constituted of 2 parts grass for each 3 parts of legume. Where no fertilizer, or P fertilizer only, was used the hay harvested was composed of only 1 part grass for each 8 or 9 parts of lucerne. Lucerne to grass seed‐ratio manipulation did not influence botanical composition nor did it affect fertilizer influe

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1966.tb00461.x

出版商:Blackwell Publishing Ltd    

年代:1966

数据来源: WILEY

摘要:

A procedure and equipment which make possible a continuous output of 250 to 300 determinations ofin vitrodigestibility of organic matter per week are described.The effect onin vitrodigestibility values of removing rumen liquor from sheep at various times before and after feeding, mixing of rumen liquors from different sheep, and nitrogen supplementation of the inoculum are investigated. Results are given of a comparison of the effect of soil contamination onin vitrodata when expressed as digestibility of dry matter and digestibility of organic matter. The levels of within and between‐batch errors are stated and the accuracy of prediction of feeding value is discusse

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1966.tb00462.x

出版商:Blackwell Publishing Ltd    

年代:1966

数据来源: WILEY

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1966.tb00463.x

出版商:Blackwell Publishing Ltd    

年代:1966

数据来源: WILEY

摘要:

In plant–breeding studies large numbers of samples, often taken from single plants, are assessed for digestibility. A modifiedin vitromethod for such estimations, which has proved accurate and less time‐consuming than other methods, is described and results obtained for some grasses are presen

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1966.tb00464.x

出版商:Blackwell Publishing Ltd    

年代:1966

数据来源: WILEY

摘要:

Experiments were conducted to analyse the effect of 3‐year‐old grass plots, under a cut‐and‐carry system, on the yields of maize and groundnut crops, and at the same time to compare the relative importance of the water‐stable aggregates and the nitrogen status of the soil. The N reserves, organic carbon and water‐stable aggregate contents of soils were higher under grass plots than in the ploughed‐up‐fallow plots. Maize yields showed a close correlation with total soil N, mineralized N after incubation for 20 days, and water‐stable aggregate contents; groundnut yields showed close correlation only with water‐stable aggregates. The effects of the variations in soil N and in the water‐stable aggregate content of the soil on the yields of maize and groundnuts were examined by multiple regression analysis of data from a

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1966.tb00465.x

出版商:Blackwell Publishing Ltd    

年代:1966

数据来源: WILEY

摘要:

Preliminary studies have been undertaken to determine the degree to which diploid and tetraploid ryegrass varieties intercross under field conditions. The results obtained through the use of diploid and tetraploid non‐red‐base tester plants indicate that pollen from tetraploid ryegrasses constitutes little or no danger to the genetic purity of diploid seed crops, even if grown in close proximity. A small proportion of viable triploid hybrids can arise in the progenies of tetraploid plants heavily exposed to diploid pollen, but here again their frequency and incidence are not of practical conseque

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1966.tb00466.x

出版商:Blackwell Publishing Ltd    

年代:1966

数据来源: WILEY