Leaf Growth Stage Research Articles

STIMULATION OF VEGETATIVE AND REPRODUCTIVE GROWTH OF BUSH BEAN PLANTS BY NAPHTHENATES

Plants of bush bean, Phaseolus vulgaris L., were sprayed with solutions of sodium and potassium naphthenates in the concentrations 50, 100, 500, 1000, 2500, and 5000 ppm. The treatments were applied when the plants were two, three, five, and seven weeks old, and also at various combinations of these times. A single application of 5000 ppm naphthenate to two-week-old plants, and multiple applications which included treatment of plants at this primary leaf stage of growth, resulted in the greatest stimulation to juvenile growth, measured as fresh and dry weights of stems and leaves, four weeks after treatment. This treatment also resulted in the greatest increase in green pod yield (20%), seven weeks after spraying, and in ripe seed production (8%). No advantage resulted from multiple treatments in these instances.

Ribonuclease isozymes in Chinese cabbage systemically infected with turnip yellow mosaic virus

An electrophoretic method has been developed for carrying out rapid and semiquantitative assays of ribonuclease (RNase) isozyme activity in crude extracts of Chinese cabbage leaves. The method has been used to study the nature of increases which have been observed in the level of RNase activity in leaves systemically infected with turnip yellow mosaic virus (TYMV). Three isozymes (RNases I, II, and III) were detected in Chinese cabbage leaves, and all were found at highest concentration in the 105,000 g cytoplasmic supernatant. Very little activity was associated with organelles. In healthy leaves, RNase III activity was high during the early stages of leaf growth, but declined to a virtually undetectable level when length exceeded 10 cm. RNases I and II showed no marked changes in activity with time. In TYMV-infected plants, the first leaf to develop systemic symptoms was studied. The RNase isozyme pattern in this leaf was identical to that of healthy leaf until after virus had begun to increase rapidly. RNase III then showed renewed strong activity, and RNases I and II also showed a small increase in activity. No new isozymes were observed in systemically infected leaves. Systemic infection with turnip mosaic virus (TuMV) caused changes in isozyme patterns very similar to those observed in leaf systemically infected with TYMV. Leaves wounded by rubbing with Carborundum showed increased RNase III activity, but those mechanically inoculated with TYMV retained high RNase III activity for a longer time than rubbed control leaves, and at a level comparable with that in systemically infected leaves of the same size.

Studies on the dropper of tulip bulbs. III

1. In order to elucidate the mechanism of forma-tion of droppers in tulip, the authors investigated the effects of various cultural conditions on the dropper formation, using the small bulbs of William Pitt and Kansas. 2. In general, tulips nursed under conditions fa-vorable for the growth of the top and roots formed great number of droppers in deeper soil. Whereas, unfavorable conditions, the formation of droppers was less vigorous. For instance, with regard to the planting depth of seed bulbs, many more droppers were formed in the shallower plot than in the deep-er one (Table 1 and 2); in the test of soil moisture condition, more were found in wet soil than in dry soil (Table 4); more were found in the soil with lower ground water level than in the soil with higher one (Table 7); in the test of CO2concentra-tion in the soil, more in the plot in which CO2 gas was supplied to the soil than in the untreated plot (Table 9); with regard to soil reaction, more in neutral soil than in alkali or acidic soil (Table 14 and 15). 3. In the experiment of the effects of nutrient conditions, where the tulips were supplied with various quantities of three elements, the growth of the plants was found to differ by the plots, but there were no recognizable differences in the formation of droppers. This result can be ascribed to the fact that the droppers had already been formed before the leaf emergence stage, when the tulip really began to absorb the fertilizer. 4. In the study of effects of photoperiodism, the growth of the tulip was shown to differ according to the treatment, but as in the case cited above, it was hard to recognize any difference in the formtion of droppers, and it is presumed that this is mainly due to the fact that the droppers had already been formed before the leaf emergence stage, when the photoperiodic treatment was begun. 5. Considering the fact that the dropper began to be formed soon after the seed bulbs had been planted, it was generally concluded that although the cultural conditions may considerably affect the formtion of droppers in tulips, the innate characters of the seed bulbs themselves seemed to be a more important cause of it.

Hypertrophy from the Uredial Stage of Bean Rust

1. Hypertrophy during the uredial stage of bean rust (Uromyces phaseoli typica Arthur) on bean (Phaseolus vulgaris L. var. Pinto) was manifested (a) by concavities or convexities in the areas of localized light or heavy inoculations of primary leaves, (b) by visible increases in the total growth of infected primary leaves when compared with that of their respective opposite healthy leaves, and (c) as measurable increases in total growth of leaves when entire plants were inoculated. 2. In the second type of comparison (b) the increase in growth resulting from rust infection was most pronounced in the later stages of leaf growth, but in the third type (c) it was clearly measurable in as little as 12 hours after inoculation. 3. In the last two types of comparison (b, c) hypertrophy occurred only where there were about 200 or less original infections per square centimeter of leaf area; more infections than this usually reduced the rate of leaf growth. 4. The transient upcurling of leaves following heavy inocu...

Photosynthesis in the Ears of Five Varieties of Wheat

IN view of the observations of Knowles and Watkin1, and of Watson and Norman2, working with wheat and barley respectively, that about one-third of the final dry weight of the plant is added during the post-ear emergence period, the assimilation by the plant during this period merits special consideration as a factor in determining final yield. The concept of the net assimilation-rate, as originally proposed by Gregory3, and so successfully used by him and others4–6 in interpreting problems of crop-growth, would thus appear to require reconsideration, since the net assimilation-rate is usually estimated up to the stage of maximum leaf-growth. After this stage the proportion of green-leaf surface to that of other green parts diminishes appreciably with time, and the assimilation by the latter might be expected to contribute substantially to ultimate dry matter output. In fact, Boonstra7, Smith8, Watson and Norman2 and Archbold9 found that, in cereals, assimilation by the stems and by the ears themselves contribute substantially to grain yield.

The Distribution of the Insoluble Nitrogen in Beta Leaves of Different Ages

ABSTRACT The distribution of nitrogen in the proteins of Beta leaves of widely varying ages has been examined. The basic N fraction is relatively abundant in the youngest stages of leaf growth, but shows no significant variations in leaves of full size. The amide N fraction rises very suddenly at the beginning of the photosynthetic stage. Its subsequent decrease has been confirmed. Possible explanations of these changes are examined.