摘要:

In a glasshouse and two growth-room trials, carried out in conjunction with 12 serial plantings in pots in the open, it was found that the phenological development ofMedicago truncatula, M. tornata, M. aculeata, M. polymorpha, M. scutellataandM. littoraliscultivars differed markedly in response to vernalization. InM. truncatulacv. Jemalong daylength interacted strongly with vernalization. Using the data of the 12 serial plantings, a mathematical model was developed to predict the period from emergence to flowering using daylength and temperature inputs. Because of the differential influence of temperature and daylength on different genotypes it was concluded that a separate model would have to be developed for each cultivar.S. Afr. J. Plant Soil1984, 1: 73–78

ISSN:0257-1862    

DOI:10.1080/02571862.1984.10634113

出版商:Taylor&Francis Group    

年代:1984

数据来源: Taylor

摘要:

The performance ofVicia dasycarpacv. Namoi in pure stand and mixed with oats at four densities, grown at three levels of N fertilizer, was studied in the field under irrigation. Both the increased plant density of oats and N fertilizer reduced the percentage vetch in the mixtures. However, the percentage vetch in all mixtures increased as the growing season progressed. Compared to pure vetch, admixing oats increased total yields significantly, and the mixtures also responded positively to N application. On the other hand, the different treatments did not differ significantly in total crude protein production. It was concluded that Namoi is an excellent legume for combining with oats for high yields of good quality fodder.S. Ah. J. Plant Soil1984, 1: 79–82

ISSN:0257-1862    

DOI:10.1080/02571862.1984.10634114

出版商:Taylor&Francis Group    

年代:1984

数据来源: Taylor

摘要:

Routine testing for Al tolerance requires that screening procedures be both rapid and simple. Growth-chamber techniques, developed in the USA, show considerable promise in this regard and were used in this study to compare the Al tolerance of 10 maize cultivars and to test the reliability of several plant performance indices proposed in the literature. Seedlings were grown under controlled environmental conditions in complete nutrient solutions, with and without Al. Visual assessment of roots grown in the presence of Al facilitated separation of the cultivars into three groups. RS5205, SR52, CG4801 and PNR394 were classed as‘good’; SSM2039, SNK2147, and SABI308 as‘intermediate’; and A475W, RO422 and TX390 as‘poor’. Visual assessments, total root length measurements and indices obtained using the primary seminal root provided measures of Al tolerance in good agreement with field performance. Topgrowth and root mass were poorly related to plant performance and relative indices obtained using root measurements in the presence and absence of Al were markedly inferior to indices obtained from Al solutions alone. The suggestion is made that screening could possibly be successfully performed using visual root ratings. Inclusion of standard genotypes would eliminate much of the subjectivity associated with such procedures.S. Afr. J. Plant Soil1984, 1: 83–86

ISSN:0257-1862    

DOI:10.1080/02571862.1984.10634115

出版商:Taylor&Francis Group    

年代:1984

数据来源: Taylor

摘要:

The patterns of gas exchange exhibited byOpuntia aurantiacaunder controlled conditions (photoperiod 12 h; day/night temperature regime 30/15°C) were investigated for plants subjected to various levels of moisture stress. Unstressed plants exhibited a typical full-CAM pattern of gas exchange in which all four phases of CAM-linked CO2exchange were evident. Net CO2uptake during phase 1 contributed up to 82% of total carbon fixed per 24 h. The transpiration: photosynthesis ratio was low (night 31; day 135), within the range exhibited by many CAM plants and indicative of a high water use efficiency. Under all conditions of water stress net carbon gain was reduced with phase IV showing the greatest reduction and phase 1 the least. On watering, stressed plantsrecoveredrapidly. Within 48 h of receiving water total CO2uptake per 24 h had risen from 5,8% to 76,5% of the unstressed value.S. Afr. J. Plant Soil1984, 1: 87–91

ISSN:0257-1862    

DOI:10.1080/02571862.1984.10634116

出版商:Taylor&Francis Group    

年代:1984

数据来源: Taylor

摘要:

Gereelde ontledings van die koolhidraatfraksies in jong appelbome het getoon dat suiker 'n relatief klein gedeelte van die koolhidrate in die boomdele uitmaak, en veral in die wortels voorkom. Stysel akkumuleer in die wortels tot finale blaarval in die winter, waarna 'n afname in styselinhoud begin, en voortduur tot ongeveer sewe weke na bottyd. Hemisellulose kom in groot hoeveelhede in die houtweefsel voor waar dit hoofsaaklik struktureel van aard is. Dit wil voorkom asof hemisellulose gedurende die herfs in die wortelweefsel gemobiliseer word, moontlik om aktiefgroeiende haarwortels te onderhou.S.-Afr. Tydskr. Plant Grond1984, 1: 92–95

ISSN:0257-1862    

DOI:10.1080/02571862.1984.10634117

出版商:Taylor&Francis Group    

年代:1984

数据来源: Taylor

摘要:

Well-fertilized wheat was found to use more water than wheat on poorly fertilized plots, but the yield was increased, resulting in increased water-use efficiency. Variations in leaf area duration after anthesis accounted for 81% of the variation in yield.

ISSN:0257-1862    

DOI:10.1080/02571862.1984.10634118

出版商:Taylor&Francis Group    

年代:1984

数据来源: Taylor

摘要:

Six levels of maize stover, expressed as percentage ground cover (0–75%) were compared under a rainfall simulator to assess the effect of surface residues on infiltration and soil loss on a clay loam soil with a 3,5% slope. Increasing the percentage ground cover resulted in increased infiltration and was even more effective in controlling soil loss. Under the experimental conditions a minimum residue ground cover of 30% was required to keep runoff and soil loss within acceptable limits.

ISSN:0257-1862    

DOI:10.1080/02571862.1984.10634119

出版商:Taylor&Francis Group    

年代:1984

数据来源: Taylor