Effects of CCC on the Formation and Abortion of Flowers in the First Inflorescence of Tomato (Lycopersicon esculentum Mill.)

Treatment of tomato plants with (2-chloroethyl)trimethylammoniumchloride (CCC) reduced their growth in height and d. wt andincreased the number of flowers formed in the first inflorescence.In plants grown at a high temperature with low light, applicationof CCC reduced the incidence of flower abortion in the firstinflorescence. Effects of -cyclopropyl--(4-methoxyphenyl)--(pyrimidin-5-yl)methanol(ancymidol) were similar to those of CCC while a third growthretardant, N-dimethylaminosuccinamic acid (B-9), was effectivein reducing growth in height but was without apparent effecton flower number or flower abortion. An interaction occurred between CCC and GA₃ such that effectsof CCC on growth and flowering were reduced when GA was alsoapplied. Yields of diffusible gibberellin-like substances fromthe shoot tips were markedly reduced by treating plants withCCC but were apparently not affected by treating plants withB-9. It is suggested that effects of CCC on flowering in tomatoare mediated, in part at least, through changes in levels ofendogenous gibberellins.     

Control of Flower Number in the First Inflorescence of Tomato (Lycopersicon esculentum Mill.): The Role of Gibberellins

The number of flowers in the first inflorescence of tomato plantswas increased by low temperatures and reduced by the applicationof GA³. The effect of GA³, was greater in a low temperatureregime (12 °C minimum) than at normal temperatures (16 °Cminimum). Increases in flower number could be produced by theremoval of young developing leaves but the treatment was nolonger effective if plants wen grown at low temperatures orwere treated with GA³. Young developing leaves were shown to be sources of diffusiblegibberellin-like substances. Leaves from plants grown in a normaltemperature regime yielded greater amounts of gibberellin-likesubstances than leaves from plants grown in the low temperatureregime. It is suggested that high levels of endogenous gibberellinsact to reduce the number of flowers formed in the first inflorescence,and that leaf removal and low temperatures influence flowernumbers by lowering levels of diffusible gibberellins in theplants. Lycopersicon esculentum, tomato, flower number, gibberellins, temperature     

A revision of Aceratherium blanfordi Lydekker, 1884 (Mammalia: Rhinocerotidae) from the Early Miocene of Pakistan: postcranials as a key

Rhinocerotids are particularly abundant and diversified in Neogene deposits of the Indian subcontinent, but their systematics is far from being well defined. Based on the revision of old collections and new findings from the Early Miocene of the Bugti Hills and Zinda Pir, Pakistan, ‘Aceratherium blanfordi Lydekker, 1884’ is a chimera, consisting of two dentally convergent but postcranially distinct rhinocerotid taxa: Pleuroceros blanfordi and Mesaceratherium welcommi sp. nov. Postcranial features appear to be much more diagnostic than craniodental morphology in this case. A phylogenetic analysis based on 282 morphological characters scored for 28 taxa (four outgroups and ingroup including both taxa of interest and a ‘branching group’) strengthens this statement and supports Pleuroceros and Mesaceratherium as monophyletic genera within Rhinocerotinae. Both genera are recognized for the first time outside Europe. In the Bugti Hills, P. blanfordi and M. welcommi are part of an exceptionally diversified rhinocerotid fauna, with up to nine species associated in the same locality (Kumbi 4f). This rhinocerotid assemblage confirms the earliest Miocene age (Agenian/Aquitanian) of the upper member of the Chitarwata Formation as a whole. Coeval homotaxic rhinocerotid faunas from Europe (France, Czech Republic) and East Africa (Uganda, Kenya) support broad and sustainable rhinocerotid interchanges amongst South Asia, Europe, and Africa under compatible environmental conditions throughout earliest Miocene times. © 2010 The Linnean Society of London, Zoological Journal of the Linnean Society, 2010, 160 , 139–194.     

The diversity of hemi-epiphytic figs (Ficus ; Moraceae) in a Bornean lowland rain forest

The diversity and niche specificity of hemi-epiphytic figs in a lowland dipterocarp forest in Sarawak were investigated in 1998. Twenty-seven fig species (264 individuals, c. 120 ha) colonized a diversity of host taxa (35 families), but densities were very low and only 1.77% of trees> 30 cm d.b.h. were occupied. There were no significant associations with host taxa or host-bark roughness but among 11 common species (≥9 individuals) the distributions of all other parameters (host-d.b.h., height and position of colonization, crown illumination, soil-texture and slope-angle) were significantly different, and we identified five fig guilds. The guilds corresponded to canopy strata, and appeared to reflect the establishment microsite requirements of different species. A fundamental trade-off within the hemi-epiphytic habit was revealed: Species colonizing larger hosts were rarer, because of lower host densities and more specific microsite requirements, but had better light environments and attained a larger maximum size. The single strangler species appeared to escape many of these constraints, and an important source of mortality caused by host-toppling, indicating the advantages of this strategy. Thus, the hemi-epiphytic figs in this community have come to fill a remarkable diversity of niches, despite low levels of competition, through the exigencies of a complex environment.  © 2003 The Linnean Society of London, Biological Journal of the Linnean Society , 2003, 78 , 439–455     

Tansley Review No. 110.

S UMMARY 367
I. I NTRODUCTION 367
II. N UMBER 368
III. S IZE 379
IV. A IR SPACE IN THE SEEDS 381
V. F LOATATION AND DISPERSAL 383
1. Air 383
(a) Physical considerations 383
(b) Dispersal 387
(c) Birds 415
2. Water 416
(a) Physical considerations 416
(b) Dispersal 416
VI. C ONCLUSIONS 417
Acknowledgements 417
References 418
Orchid seeds are very small, extremely light and produced in great numbers. Most range in length from c . 0.05 to 6.0 mm, with the difference between the longest and shortest known seeds in the family being 120-fold. The 'widest' seed at 0.9 mm is 90-fold wider than the 'thinnest' one, which measures 0.01 mm (because orchid seeds are tubular or balloon-like, 'wide' and 'thin' actually refer to diameter). Known seed weights extend from 0.31 lg to 24 μg (a 78-fold difference). Recorded numbers of seeds per fruit are as high as 4000000 and as low as 20–50 (80000–200000-fold difference). Testae are usually transparent, with outer cell walls that may be smooth or reticulated. Ultrasonic treatments enhance germination, which suggests that the testae can be restrictive. Embryos are even smaller: their volume is substantially smaller than that of the testa. As a result, orchid seeds have large internal air spaces that render them balloon-like. They can float in the air for long periods, a property that facilitates long-distance dispersal. The difficult-to-wet outer surfaces of the testa and large internal air spaces enable the seeds to float on water for prolonged periods. This facilitates distribution through tree effluates and/or small run-off rivulets that may follow rains. Due to their size and characteristics, orchid seeds may also be transported in and on land animals and birds (in fur, feathers or hair, mud on feet, and perhaps also following ingestion).     

The role of some cyclorrhaphan flies as carriers of human helminths in Malaysia

The role of some adult flies (Diptera: Cyclorrhapha) as carriers of helminth parasites of man was studied at four sites in Malaysia: a refuse dump, where no helminth-positive flies were detected, and in three peri-domestic situations where four species of flies carried up to three types of nematodes. The dominant fly species Chrysomya megacephala (Fabricius) carried eggs of the roundworm Ascaris lumbricoides L., the pinworm Trichuris trichiura (L.) and hookworm on the adult external body surface and in the gut lumen, in association with Bukit Lanjan aborigines. Chrysomya rufifacies (Macquart) and Sarcophaga spp. also had Ascaris lumbricoides and Trichurus trichiura eggs in their gut contents. Human helminths were not recovered from Lispe leucospila (Wiedemann), Lucilia cuprina (Wiedemann) or the housefly Musca domestica L. In an urban slum area of Kuala Lumpur city, filariform larvae identified as the hookworm Necator americanus (Stiles) occurred in the intestines of the face-fly Musca sorbens Wiedemann (22 larvae per 100 flies) and of Chrysomya megacephala (4.5 larvae per 100 flies). This concentration of apparently infective N. americanus in M. sorbens, a fly which often breeds in faeces and browses on human skin, could have transmission potential.     

Efficiency of K+ Utilization by Barley Varieties: Activation of Pyruvate Kinase

Barley (Hordeum vulgare L.) varieties differed in their raponseto [K⁺]₀, in terms of their utilization efficiencies (UE = freshweight. concentration of [K⁺]₁^–1). At low [K⁺]₀, Compana,an efficient-non-responder demonstrated superior utilizationof absorbed K⁺. On the other hand, at high [K⁺]₀, Fergus (anefficient responder) and BT 334 (an inefficient responder) hadhigher UE values for K⁺ than Compana which performed poorlyat this [K⁺]₀. Kinetic parameters for K⁺ activation of the enzyme pyruvatekinase from 12 barley varieties, representing a range of UEvalues, were determined. Varieties showed substantial differencesin their V_max values (P<0·01). Compana, an efficientvariety, had the highest V_max (31 µmol g^–1 freshwt. h^–1) which was about 50% higher than that of Mingo,an inefficient variety. By contrast, K_m values for the enzymeswere not significantly different among varieties The mean valuesfor all varieties (3·9±0·15 mol m^–3K⁺) is far below the estimated cytoplasmic [K⁺] (100-200 molm^–3). It is, therefore, unlikely that differences in theutilization of K⁺ by these varieties can be explained on thebasis of differential requirements for (K⁺) activation of theseenzymes. Alternative possibilities for differences in the utilizationof K⁺ are discussed. Key words: K⁺ utilization efficiency, Pyruvate kinase, Barley varieties     

Histochemical Studies of Sclereid Induction in the Shoot of Rauwolfia Species: I. CYTOCHROME OXIDASE

Results of histochemical tests for cytochrome oxidase activityin four species of Rauwolfia have been reported. The cells beneaththe terminal shoot meristem constitute the pith. Histochemicaltests showed intensified enzymatic activity in those cells ofthe pith which would differentiate as sclereid initials. Similarcytochrome oxidase activity also occurred in the sclereid initialsand the developing sclereids. The cytochrome oxidase activitywas associated with two types of particulate formation, thegranular and rod-shaped. The ground parenchymatous cells ofthe pith and the leaf-base showed very little enzymatic activityof cytochrome oxidase. The characteristic indophenol blue colorationdue to cytochrome oxidase activity did not appear in controlsections. Physiological changes correlated with morphogeneticexpression of some pith cells demonstrate that the physiologicalchanges occur before the initiation of sclereids in the morphologicallyhomogeneous parenchymatous cells of the pith. Intensified cytochromeoxidase activity was also recorded in the meristematic tissuesof shoot apex, procambium, axillary buds and the laticiferouscells of Rauwolfia.     

Interactions of Meloidogyne javanica, Fusarium udum and Rhizobium on pigeon pea in the presence of nickel and cobalt as pollutants

The interactions between Meloidogyne javanica, Fusarium udum and Rhizobium on pigeon pea, in the presence of nickel (Ni) and cobalt (Co) as soil pollutants, were studied. In single inoculations, M. javanica caused a reduction in plant growth, particularly at higher inoculum levels (1000 and 10 000 JJ₂). Fusarium udum induced wilting symptoms and the higher concentrations of Ni and Co suppressed plant growth. Meloidogyne javanica and F. udum interacted to show more severe wilting symptoms than F. udum alone. Wilting was completely inhibited by Ni but reductions in plant growth and nodulation occurred. In the presence of Ni, M. javanica did not cause galling but nodulation was suppressed. Cobalt also suppressed wilting and nodulation but interacted with M. javanica to increase root galling and to reduce plant growth by a greater amount than the total of reductions caused by the individual treatments.