Plants In Different Stages Research Articles

Fractionation of nucleic acids isolated by the phenol- and DEP-methods from leaf tissues at different stages of development

The phenol method and a new method based on the use of diethylpyrocarbonate (DEP) as a nuclease inhibitor were compared with respect to the yield of total nucleic acid extractable from barley and tobacco plants in different stages of development. The percentage distribution of different nucleic acid species in the extracts prepared by the two methods was also studied by sucrose density gradient centrifugation and MAK column chromatography. The nucleic acid yield in the extracts from first leaves of 11-day-old barley seedlings was higher with the DEP method than with the phenol method. With barley the same percentage distribution of the different nucleic acid species was obtained with both methods. By contrast, with tobacco (except for very young tissues) a preferential loss of hrRNA was observed when using the DEP method. The ageing of barley leaf tissues was characterized by a virtual increase in DNA apparently due to a preferential breakdown of rRNA. This pattern, characteristic of ageing tissues, was more pronounced with attached leaves than with detached, “artificially aged” tissues.

Reduction of Corn Yield by First-Generation Southwestern Corn Borers

The effect of first-generation southwestern corn borers ( Zeadiatraea grandiosella Dyar) on the development and yield of dent and sweet corn was studied at Stillwater, Okla., in 1955. Plants in different stages of growth were manually infested with newly hatched larvae. Plant height was not significantly affected, but the weight of plants was reduced moderately by the borers. There was a greater reduction in yield of grain from small than from large corn plants. Dead heart was also more prevalent in the plants that were smallest at the time of infesting. Since small plants had greater damage than larger ones, the earliest planting consistent with good agronomic practices should avoid the greatest damage by the first generation of this borer. Dissections made at harvest did not give an accurate measurement of first-generation populations.

Effect of Curly Top-Infective Beet Leafhoppers on Watermelon Plants in Different Stages of Development

Curly top-infective beet leafhoppers (Circulifer tenellus (Baker)) were placed on watermelon plants in different stages of development. Growth was severely retarded when plants were infested in the cotyledon stage but were apparently unaffected when infested in the two-leaf stage. Therefore little damage can be expected from curly top in watermelons except where plants in the cotyledon stage are heavily infested.

Water Soluble Carbohydrates in Forage Crops and Their Relation to the Production of Silage

Summary Leguminous and non-leguminous plants were collected and were analyzed for their water-soluble carbohydrates. Plants of different stages of maturity were collected. They were taken around midday and the analysis started immediately. The tabulated results show the percentages of fermentable carbohydrates in the sap of the plant, in the fresh and dry weight of the plant and in the moisture calculated for each sample to a uniform basis of 80 per cent. Notes that might have some bearing on the production of silage from these crops were made. The wide difference in the water-soluble carbohydrates of these two types of forage crops suggested that the legumes are deficient in fermentable carbohydrates and thus fail to produce a silage of satisfactory quality. Acting on this suggestion, silages were made by supplementing the fermentable sugars in the legumes with sueh substances as corn sugar and molasses. Since these carbohydrates are converted into organic acids both organic and mineral acids were also employed to reduce the pH of the freshly cut material to a point which reduced materially the microbial activity. It was found that silages of superior quality could be made by these methods. In the discussion it was suggested that phosphoric acid might be employed profitably to preserve the fodders; to increase the phosphorus content for animals and to increase the fertilizing value of the farm manure.

XIII. On the organization of the fossil plants of the coal-measures. —Part III. Lycopodiaceæ (continued)

In the last memoir which I laid before the Royal Society I described a number of forms of Lepidodendroid plants from the Coal-measures, without making any material attempt to ascertain the relationship which they bore to each other. I now propose to carry the subject somewhat further, and to show that some of these apparently varied forms of Lycopodiaceæ merely represent identical or closely allied plants in different stages of their growth. The discovery of some remarkable beds in Burntisland, by George Grieve, Esq., and his persistent kindness in supplying me abundantly with the raw material upon which I could work, have enabled me to do this in a manner, at least, satisfactory to myself. Upon the geology of these remarkable beds I will not now enter, beyond saying that they appear to have been patches of peat belonging to the lower Burdiehouse series, which are now imbedded in masses of volcanic amygdaloid. The stratum, where unaltered by contact with the lava, is little more than a mass of vegetable fragments, the minute structure of most of which is exquisitely preserved. The more perfect remains that are capable of being identified belong to but few types. The most abundant of these are the young twigs of a Lepidodendron , portions of the stem of a Diploxylon , stems of a remarkable Lycopodiaceous plant belonging to my new genus Dictyoxylon (but which, for reasons to be stated in a future memoir, I propose to unite with Corda’s genus Heterangium , under the name of H. Grievii ), and fragments of Stigmaria-ficoides . Along with these occur, but more rarely, several other curious Lycopodiaceous and Fern stems, and those of an articulated plant, which I believe to be an Asterophyllites ; also some true Lepidostrobous fruits and myriads of caudate macrospores belonging to the Lepidostrobi . The first point to be noted is that all the Lepidodendroid branches are young twigs. No one example of a large stem has been found presenting exactly the same structure as these small branches, which, as already stated, are so abundant. On the other hand, all the Diploxylons are large branches or matured stems. These facts at once suggested the inquiry whether the two plants referred to might not be complementary to each other. A careful and very extended study of a large number of specimens has convinced me that such is the case. I have made more than a hundred sections of the two forms, and the result has been a remarkably clear testimony that the Lepidodendra are the twigs and young branches of the Diploxylon -stems. I am also led to the conclusion that the Lepidostrbi , with their peculiar macrospores and microspores, belong to the same plant. I will examine each of these forms in detail.