The effect of vesicular-arbuscular mycorrhizal exposure period on their colonization of and spore production in tomato seedlings (Lycopersicon esculentum Mill.), and on host biomass

1994 ◽  
Vol 51 (3) ◽  
pp. 287-292 ◽  
Author(s):  
Thomson T. Edathil ◽  
S. Manian ◽  
K. Udaiyan
Genome ◽  
1991 ◽  
Vol 34 (6) ◽  
pp. 929-934 ◽  
Author(s):  
P. Banks ◽  
E. J. Britten ◽  
G. H. Gordon

Germinating seeds of rape (Brassica napus L.) and of tomato (Lycopersicon esculentum Mill.), and 1-month-old tomato seedlings, were treated with para-fluorophenylalanine to change chromosome numbers. A number of morphological aberrations were found in treated plants of both species, some of which were also observed in progeny of treated tomatoes. Aneuploids and polyploids were confirmed cytologically in treated plants of both species. The investigations confirm the suggestion previously made for maize, that para-fluorophenylalanine is capable of changing chromosome numbers and the resulting morphology of plants of widely different phylogenetic categories.Key words: Para-fluorophenylalanine, chromosome number changes, plants, tomato, rape, aneuploids, polyploids, morphological changes.


1993 ◽  
Vol 71 (10) ◽  
pp. 1328-1335 ◽  
Author(s):  
Narayan C. Talukdar ◽  
James J. Germida

Factors affecting the propagation of vesicular–arbuscular mycorrhizal fungi (VAMF) Glomus clarum, Glomus mosseae, and Glomus versiforme isolated from Saskatchewan soils were assessed in growth-chamber studies. Initially, lentil (Lens esculenta L.), maize (Zea mays L.), and a sorghum (Sorghum bicolor (L.) Moench) and sudangrass (Sorghum sudanense (Piper) Hitch.) hybrid were inoculated with G. clarum and grown in 2 or 6 kg of soil–sand (1:1) substrate until maturity. All three crops supported growth and spore production by G. clarum, but the maize plant yielded the largest number of spores. The ability of G. clarum to produce large numbers of spores reflects either an inherent ability of this VAMF strain to sporulate or a favorable interaction (related to spore production) with a maize host crop. Twice as many G. clarum spores per gram of soil–sand substrate were obtained from 2-kg pots compared with 6-kg pots. Enhanced spore production in the smaller pots was related to poor plant growth and, apparently, nutrient stress. Plants grown in 2-kg pots were stunted, yielded less biomass, and exhibited severe symptoms of P and N deficiency. Monospecific cultures of G. clarum, G mosseae, and G. versiforme were produced using maize plants grown in 2-kg pots. Under these conditions the level of spore production was G. clarum > G. versiforme > G. mosseae. Storage of the VAMF inoculants at 7 °C, compared with 25 °C, enhanced spore viability. This was evident from a reduction in VAMF colonization and spore production in wheat (Triticum aestivum L.) and the sorghum–sudangrass hybrid plants inoculated with G. mosseae spores stored at 25 °C. Osmotic stress exerted on G. mosseae spores during density-gradient centrifugation had no effect on their viability. Key words: vesicular–arbuscular mycorrhizal fungi, Glomus spp., host crops, substrate mass, nutrient stress.


1990 ◽  
Vol 70 (1) ◽  
pp. 345-356 ◽  
Author(s):  
A. DUGAL ◽  
S. YELLE ◽  
A. GOSSELIN

Net photosynthesis, stomatal conductance, internal CO2 concentration and transpiration were measured on the fifth well-developed and excised leaf of tomato seedlings (Lycopersicon esculentum Mill. ’Vedettos’) 48–83 d old. These measurements were taken in order to monitor the evolution of the gas exchanges of seedlings exposed to concentrations of 330 or 1000 ppm, continuously, to 1000 ppm from 06: 00 h to 10: 00 h or to 1000 and 330 ppm alternately every 2 h. CO2 enrichment substantially increased the net photosynthesis rate of the seedlings, particularly at the beginning of the experiment. The long-term effects of CO2 enrichment subsided after a few weeks of treatment. Intermittent CO2 enrichment is partially helpful in remedying the loss of effectiveness of the CO2 after a long period of enrichment. High CO2 concentrations reduced the opening of the stomata. Our work shows that maintaining a high internal CO2 content in the leaves would indirectly reduce the stomatal conductance of the seedlings. However, our results show that the long-term loss of photosynthetic efficiency in the enriched seedlings cannot be attributed solely to an increase in the resistance of the stomata, since the internal CO2 concentration of the leaves remains very high regardless of which method of CO2 enrichment is used. Continuous CO2 enrichment improved the water uptake efficiency of the seedlings.Key words: Carbon dioxide, intermittent enrichment, gas exchanges, tomato, greenhouse, Lycopersicon esculentum Mill.


1996 ◽  
Vol 47 (5) ◽  
pp. 651 ◽  
Author(s):  
JK Olsen ◽  
JT Schaefer ◽  
MN Hunter ◽  
DG Edwards ◽  
VJ Galea ◽  
...  

This greenhouse study investigated the effects of the addition of vesicular-arbuscular mycorrhizal (VAM) inoculum (Glomus mosseae [Nicol. & Gerd.] Gerdemann & Trappe and Glomus etunicatum Becker & Gerdemann) on capsicum (Capsicum annuum L. cv. Target), sweet corn (Zea mays L. cv. Snosweet), and tomato (Lycopersicon esculentum Mill. cv. Floradade) grown in a low P sandy loam (6 mg NaHCO3-extractable P/kg) with 5 rates of P (0, 10.3, 30.9, 92.7, or 278 mg P/kg oven-dry soil; P1, P2, P3, P4, or P5, respectively) and 2 rates of N (50 or 200 mg N/L in irrigation solution; N1 or N2, respectively). The growth periods (from sowing to harvest) for the 3 crops were as follows: 27 August-22 November 1993 for capsicum, 26 August-29 October 1993 for sweet corn, 31 August-22 October 1993 for tomato. For VAM-inoculated capsicum at PI, the dry weight (10.03 g/plant) and mean P concentration in the 5 youngest mature leaves (0.14%) were greater (P < 0.05) than those for uninoculated plants (0.28 g/plant; 0.09% P); a high coefficient of variation necessitated the use of log, transformed data to show differences. At low P rates, dry weight of sweet corn (P1, P2) and tomato (P1) plants colonised with VAM did not differ (P > 0.05) from uncolonised plants, despite inoculated plants having higher P concentrations in index tissues. At intermediate P rates, dry weights of inoculated plants were lower (P < 0.05) than those of uninoculated plants of sweet corn at P3 (81.1 and 102.2 g/plant, respectively) and of tomato at both P2 (11.7 and 34.5 g/plant, respectively) and P3 (39.6 and 52.1 g/plant, respectively). For all 3 crops, a lack of VAM response at high P ( >P4) was related to a lower (P < 0.05) VAM colonisation. The percentage root length colonised by VAM at P5 was only 6.8, 19.6, and 2.4% of that measured at P1 in the case of capsicum, sweet corn, and tomato roots, respectively. Increasing N concentration in the irrigation solution from 50 to 200 mg/L increased (P < 0.05) VAM colonisation of sweet corn (from 28 8 to 36 2%), but had no effect on capsicum and tomato.


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