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Publisher Summary This chapter describes the methods for preparing the leaf culture. In contrast to most other plant cultures, excised leaves do not undergo indefinite growth in culture, even when provided with adequate nutrients and transferred or subcultured at intervals. The leaf, in culture as on the intact plant, develops as a determinate organ, and its ability to develop in this way in isolation shows that it is self-differentiating. The objective of most leaf culture is to study the total development of this organ under conditions which can be controlled in contrast to the largely unknown circumstances in which the leaf develops as a part of an intact plant. It is even possible in certain cases to investigate the process of leaf determination by excising primordia of leaves prior to the completion of this process. The chapter discusses that the leaves grown from primordial stages to maturity in culture are relatively normal in form but they are greatly reduced in size and often show reduction in morphological complexity. more...

When corn seedlings absorb large amounts of ammonium nitrogen from complete nutrient solutions high in ammonium, soluble nitrogen compounds accumulate in the tissues of shoot and root but the true protein remains relatively constant (15). Ammonia does not accumulate rapidly in tissues of the corn plant until asparagine, glutamine, a-amino nitrogen and peptides have reached relatively high values. In order to determine the role of these compounds in protein catabolism, the changes in nitrogen composition of detached leaves maintained in darkness and in intermittent light and darkness were studied and the results are reported here. Yarwood (20) has recently reviewed the subject of detached leaf culture. Similar studies have been made on leaves of rhubarb (14), barley (21), Kikuyu grass (17, 18), and sudan grass (18), and oats (17) cultured in continuous darkness, and tobacco (12) and runner bean leaves (2) in light and darkness. The results show in general that protein hydrolysis begins soon after the leaf is detached and that amino nitrogen, and either or both of the amides, glutamine and asparagine, accumulate. Whether this loss of protein on detachment of the leaf is due to lack of supply of some external factor or hormone or to some internal factor has been the object of speculation (1, 16, 13). Materials and methods more...

The effect of white light and long- and short-wave ultraviolet light on spore germination, penetration and infection was determined for Ascochyta chrysanthemi on chrysanthemum, A. pisi and A. pinodes on pea and A. imperfecta on lucerne, by means of a detached leaf culture technique. White light and longwave ultraviolet light had no effect on these processes. Short periods of exposure to short-wave ultraviolet light resulted in increased infection, which was most marked in A. chrysanthemi and A. imperfecta , whilst longer exposures (up to 200 s) caused a progressive reduction in infection and spore viability. The increased infection by A. chrysanthemi was due to an increase in the susceptibility of the leaf tissue as a result of exposure to short-wave ultraviolet light. The response of A. chrysanthemi on irradiated leaf tissue of other plants was also altered; the susceptibility of lettuce was increased and the partial resistance of sunflower was destroyed. Spores of all four species survived the effects of short-wave ultraviolet irradiation better on leaf tissue than on agar, and only spores of A. chrysanthemi showed a stimulation in germination on leaf tissue after short periods of exposure to ultraviolet light. There was no alteration in the growth rate of colonies which had developed from spores on agar which had survived irradiation by any of the three light sources. more...

A number of hybrid tea roses were tested for suitability to rear the European red mite in detached leaf culture. It was possible to culture Panonychus ulmi (Koch) on an unnamed variety of hybrid tea rose continuously for 13 months, Subsequently, another rose, ‘Flaming Peace,’ was found to be a more adequate host and was substituted for the unnamed variety. more...

Plant introduction lines of Cucumis spp. were screened in the greenhouse for resistance to Tetranychus urticae Koch by visual assessment of injury. Selected lines and cultivars were tested in the laboratory for further characterization of resistance using detached leaf culture. The high resistance found in C. africanus lines was apparently attributable to both antibiosis and nonpreference. The moderate resistance of 2 lines of C. anguria and one of C. longipes was considered to be due to nonpreference and plant tolerance. The latter form of resistance probably exists in lines of C. ficifolius , C. melo , and C. leptodermis . C. sativus ‘SMR-58’, and C. melo ‘Iroquois’ were highly susceptible to T. urticae . more...