Sudden Temperature Drop Research Articles

GENETIC DIFFERENCES IN LEAF ABSCISSION AND THE ACTIVITY OF NATURALLY OCCURRING GROWTH REGULATORS IN PEACH

Leaf abscission in peach is correlated with the release of tryptophan into the cytoplasm following a sudden drop in air temperature below the physiological minimum. The tryptophan accumulates in the variety Elberta and results in increased activity levels of 5-hydroxytryptamine, 5-hydroxyindoleacetic acid, and an unidentified neutral growth promoter. The rapid defoliation of the canker resistant variety Elberta was, however, associated more closely with the endogenous levels of tryptophan and 5-hydroxytryptamine. Susceptible Dixired variety, which defoliates slowly, contains lower activity levels of these compounds at the time of leaf abscission, and shows enhanced activity of kynurenic and xanthurenic acids throughout this same period. This suggests that tryptophan does not accumulate in Dixired to cause rapid abscission because of a greater genetic capacity for degradation by way of the kynurenine, hydroxyanthranilic, nicotinic acid pathway common in the metabolism of animals.

GEOGRAPHICAL DISTRIBUTION OF LOWER UPPER AIR TEMPERATURE ABOVE CITY AREAS

Since 1955, a study has been made on geographical distribution of air temperature in and around city areas in Japan using the moving observation technique by cars. A new thermistor thermometer was installed on the front bumper of the car and while driving the outdoor temperatures were observed at almost every 30 seconds or about at 500 m intervals. The time lag of the thermometer was only 3 seconds. One moving observation lasted for about one and half hours. The temperatures at 100-150 stations within the area of about 4 km square were measured. Then a very detailed temperature distribution maps were drawn in and around city areas. However, the observed temperatures were those of approximately 1.5 meters above the street. They were often affected by local influences, such as the width and the direction of the street etc. So in order to analyse city effects on temperature distribution, it would be preferable to measure more representative or more generalized values, such as lower upper air temperatures above the cities. Instrumentation and Technique: A small-sized aspiration thermistor thermometer, was made by the observers Its total weight is only 85 grs including an electric motor and a dry battery of 1.5 volts as is shown in Fig, 1. This upper air thermometer has been hanged by vynil-covered electric wire below a pibal balloon of 100 grs. The diameter of the wire is 0.3 mm and it is also used to capture the balloon. The balloon was carried by the observers from station to station which were distributed fairly evenly in and around city areas. Then it was lifted up to 10 m, 20 m and 30 m levels at each station and temperatures were observed respectively. Particularily on 30 meters level, the observations were done every 30 seconds for 10 minutes successively in order to know its representative condition. The upper air observation wes carried out simultaneously with the surface moving observation within one and a half hours. Usually from 4 to 5 moving observers' groups were organized and they measured the upper air temperature above 15-30 stations in the areas of about 4km square. Such observations were carried on medium-sized cities in Japan having 30, 000-50, 000 population in their built-up areas. For their examples, they have picked up the city of Ogaki city in Central Japan and Yonezawa City in Northern Japan. The Observation Height: There are two requirements to decide a suitable observation level above the city areas: 1) The layer should be affected sensitively by the surface conditions below, but should not be disturbed by very local influences. 2) The layer should have smaller micro-variations of temperature than any other layers. Several experimental observations were made in Tokyo and Yonezawa. Successive temperature recordings at 1.5 minutes intervals were done at the micro-wave tower of 60 m high and the television tower of 130 m high in the central part of Tokyo in 1957 and 1958. The results were as follows (Figs. 2-5): 1) Temperature inversions in the evening were often observed after midnight at the central part of the city even in midsummer. 2) In the daytime, the micro-variation at different levels showed different variation patterns and magnitude. However, at night-time they became quite small at every layer. 3) Sudden temperature drops and sudden decreases of the micro-variations took place at every layer simultaneously when the sun was covered by clouds. 4) According to the 1957's observations, as are shown in Fig. 4, the micro-variation patterns at 1.5 m, 27 m and 73 m layers were fairly similar. Their mutual correlation coefficients were high and significant. However, the variation pattern of 130 m layer was different. The wind observations at these levels were also done on the same occasion and we found the existence of the wind-speed maximum layer about at 60-100m levels.

Expanding air causes sudden temperature drop

Expanding air causes sudden temperature drop

OVIPOSITION IN CERTAIN COLEOPTERA

SUMMARY Methods for satisfactory oviposition studies of Tenebrio molitor L., Tribolium confusum Duv., Sitodrepa panicea L., Lasioderma serricorne F., and Dermestes vulpinus F. are described. Four types of oviposition cycle are recognized: Short‐lived species which lay all their eggs in a few days. Long‐lived species laying continuously over a long period. Rather short‐lived species laying batches of eggs at short intervals. Long‐lived species with two or more periods in which oviposition is more or less continuous, separated by a long period in which there is no oviposition. The normal oviposition cycles of Lasioderma, Sitodrepa, Tenebrio and Tribolium are described. Records of parthenogenesis in Coleoptera suggest that it is almost confined to the Curculionidae, and even there it is rare. Of the five species studied by the author, no virgin females laid any fertile eggs, and only those of Tribolium and Tenebrio laid any eggs at all. In many beetles which will copulate more than once, a single mating is sufficient to ensure that all or most of the eggs shall be fertile. In certain species, however, the oviposition rate falls if there are not repeated matings. This is shown to be the case in Tribolium, where a second mating, even in females still laying fertile eggs, has a marked stimulatory effect. There are usually both upper and lower limits of temperature for oviposition. In the experiments on Tenebrio and Tribolium it appeared that the upper limit was determined by the temperature which was soon lethal to the beetles; the lower limit lay between 14 and 16°C. In Tribolium it was shown that a sudden drop in temperature from 27 to 18°C. has a marked stimulatory effect on the oviposition rate of the beetles after they had been returned to 27°C. The conditions of atmospheric humidity and of food moisture‐content suitable for different species are very varied. Certain species, such as Dermestes, must drink water if they are to lay normally. Tribolium can live, and lay more than half of the normal number of eggs, in a flour and in an atmosphere approaching complete dryness. Tenebrio requires no water to drink, but even in 20 % relative humidity (at 27°C.) oviposition is very greatly reduced. Certain species, especially those of the short‐lived type, can lay eggs in empty glass tubes in the absence of any food or other oviposition site. Lasioderma. however, though short lived, requires an oviposition site; for this muslin will partially replace food. If it has first been fed on a suitable flour, Tribolium will lay a few eggs in pure starch, which is not a sufficient food for the development of the ovaries. It will not lay in empty tubes even if it has been fed. The changes in the appearance of the reproductive organs of Tribolium during the life of a female are described. After oviposition the degenerating egg follicles form the so‐called “corpus luteum”. This character is more easy to see when the ovary is empty, for example in a female in which lack of food has inhibited egg formation, than when egg production is continuing actively. It is shown that in Tribolium any external factor which interrupts oviposition will produce an ovarial cycle like that already described in the Scolytidae, in which family the interruption is normally due to hibernation or to the need for special food after laying a number of eggs.