中国水稻三化螟防治研究的进展

在中国为害水稻較重的螟虫已知有6种,以三化螟 Tryporyza incertulas (Wlk.)最为重要,分布于我国中南部稻区。本文阐述了气候、食料、水稻栽培制度和生物等因素对三化螟种群数量变动的影响,并指出作为螟虫食料的水稻及其栽培制度的作用更为明显。研究証明,三化螟的产卵、侵入、成活、繁殖和为害都与水稻的生育期有密切关系,水稻的分蘖期及孕穗期,都是水稻最易受害的生育期,在这两个时期被害,会造成枯心或白穗;而秧田期、移植至回青期、圓稈期和成熟期都对螟虫不利。螟虫的发生基数和生活环境条件,密切影响种群数量的变动,而这些都受水稻栽培制度的影响。发生基数决定于春季螟虫的有效虫源,其数量的大小对当年的螟虫,尤其对第一、二代的发生量有密切关系。螟害程度主要决定于:(1)种群数量和(2)水稻最易受害的生育期与螟虫盛发期配合程度的综合作用。为了加強防治,各地区必须因地制宜,利用耕作栽培措施,一方面尽可能消灭虫源、压低发生基数、控制以后各代螟虫的发生;另一方面力求改进栽培技术、調节水稻生育期,恶化螟虫的生活条件,避免或減輕螟害。化学防治也是治螟的一項重要措施。目前广泛应用的药剂是6％丙体六六六,每亩用量在防治枯心时为1.5斤,防治白穗为2斤。主要的施药方法为泼浇和撒毒土,两者对防治枯心的效果都很好;撒毒土防治白穗的效果虽稍差,但操作簡便易行。在螟虫发生期內,适值分蘖和孕穗的水稻田一般都要施药;但預测螟害低于1％的田块,可不防治。防治枯心的施药适期一般在孵化高峯前1—2天天开始,如虫量很大,要提前到盛孵始期用药。防治白穗的施药适期是:在蚁螟盛孵前孕穗的水稻,普通在盛孵始期开始施药;蚁螟盛孵后孕穗的水稻,在孕穗始期开始用药。稻螟是我国长期以来的一种严重害虫,解放前因螟害常年損失稻谷10％以上。解放后,在党和政府的領导下,科学技术有了显著的进展,治螟工作貫彻了“防治并举、以防为主”的方針,“以农业防治为基础,重点使用药剂綜合防治”的策略;采用了准确的預测預报;开展了群众性的防治活动,基本上控制了螟虫的危害,1663年的螟害率已压低到2％左右,不少地区已降低到1％以下。这都是在总路线、大跃进、人民公社三面紅旗光輝照耀下,領导、技术人員、群众三結合所取得的成果的     

Retention of Selenium in Kidneys,Liver and Striated Muscle After Prolonged Feeding of Therapeutic Amounts of Sodium Selenite to Pigs

Sodium selenite was mixed in a commercial pig food so as to increase the original selenium content (0.126 ppm) by 1.2 ppm. The supplemented food was given to 7 pigs during 78 days. A control group of as many pigs was given the non-supplemented commercial food. The pigs were killed, starting 4 hours after the last selenium-supplemented food had been given and then with intervals during the next 14 days. Small but significant increases of tissue selenium were noticed in liver and striated muscle as compared with the control animals. The kidneys showed no increase.     

Quantitative Determination of Proteolytic,Lipolytic and Haemolytic Activities in Semen of Some Animal Species

1. Methods for quantitative determination of proteolytic, lipolytic and haemolytic activities and egg yolk factors in semen are described.2. Comparative quantitative determinations of these enzyme activities in the semen of goat, ram, bull, boar, dog and horse have been carried out.3. Special interest attaches to the egg yolk turbidity factor which is found in goat semen and, in small concentrations, also in boar semen.4. As each species appears to have its specific enzyme pattern, regular enzymatic control does not seem to have great significance.     

Studies on in Vitro Erythrocyte Uptake of I131-Labelled 1-Triiodothyronine as A Test of Thyroid Function in Dairy Cattle

Uptake of I¹³¹-labelled triiodothyronine by erythrocytes (EU test) as a test of thyroid function has been studied in cattle. The normal EU value for 141 Swedish Red-and-white cows was 6.99 ± 0.95 (range 4.45–10.23) at an incubation time of one hour. Statistically significantly higher values were obtained for newly-calved cows. The EU values for calves are significantly higher but by 12 to 18 months of age decline to the same level as for older cows.The principle of the test is described and the results obtained compared with those for human beings. The EU test is suitable for screening thyroid function for large groups of animals and for studying associations between thyroid activity and different production qualities.     

STUDIES ON WEED SPECIES OF THE GENUS POLYGONUM L.

Summary. Seeds of Polygonam persiaria were collected from seven localities during 1962. In 1963 plants of these seven populations were grown in the field and sampled at regular intervals over the period 21st June to 13th August. At all samplings there were differences between populations in total dry weight, in leaf area index and in total nitrogen content, and populations also differed in the date of flowering. The populations also differed significantly in relative growth rate, leaf area ratio, net assimilation rate and relative nitrogen absorption rate. The variations in net assimilation rate did not appear to be closely associated with variations in leaf area index. Certain growth attributes were correlated with the latitude of origin, and it is tentatively suggested that the populations may represent genetically distinct latitudinal ecotypes.
Études sur des espèces de mauvaises herbes du genre Polygonum L.     

Magnetic flux transport on the sun

Although most of the magnetic flux observed on the sun originates in the low-latitude sunspot belts, this flux is gradually dispersed over a much wider range of latitudes by supergranular convective motions and meridional circulation. Numerical simulations show how these transport processes interact over the 11-year sunspot cycle to produce a strong "topknot" polar field, whose existence near sunspot minimum is suggested by the observed strength of the interplanetary magnetic field and by the observed areal extent of polar coronal holes. The required rates of diffusion and flow are consistent with the decay rates of active regions and with the rotational properties of the large-scale solar magnetic field.     

Effect of dietary inclusion of ascorbic acid and palm oil on the performance of laying hens in a hot tropical environment

1. Two experiments were conducted to evaluate the effects of including ascorbic acid (AA), palm oil or a combination of both in the diets of laying hens during the hot months in a tropical environment.

2. The inclusion of AA improved egg production, food intake and efficiency of utilisation, and decreased the cost of food per kg egg. The addition of 400 mg AA/kg diet gave the most efficient performance.

3. Palm oil inclusion reduced the effect of heat stress and increased egg production, egg weight, food intake and efficiency of utilisation.

4. When 200 mg AA and 50 g palm oil/kg were used, additive responses were obtained with further improvements in egg production, food cost and efficiency.

5. Ascorbic acid and palm oil when fed alone or in combination reduced the incidence of cracked eggs.

6. Thus, 400 mg ascorbic acid/kg of diet, 50 g palm oil or 200 mg AA plus 50 g palm oil/kg diet ameliorated the effects of heat stress in laying hens.     

Contribution of lipoprotein lipase activity to the differential growth of three adipose tissue depots in young broiler chickens

1. The growth of three distinct adipose tissue depots around the abdomen, neck and thigh was measured in a commercial strain of broiler, and related to the changes in activity of lipoprotein lipase within each depot.

2. At 10 d of age there was no significant difference between the weights of the depots. Thereafter the abdominal fat pad exhibited a much greater rate of growth than the other two depots so that by 55 d of age the abdominal fat pad was 4 times the size of the leg depot and 3.4 times the size of the neck depot.

3. Changes in total lipoprotein lipase activity for all three depots showed a similar pattern to the changes in their weight.

4. When [¹⁴C]‐VLDL was injected intravenously into birds at 15 and 57 d of age the percentage taken up into the abdominal fat pad was greater than that into the other two depots at both ages. At 57 d of age the abdominal fat pad had a 2.3‐fold greater uptake than at 15 d whereas the other two depots showed no significant differences at the two ages.

5. These results provide further evidence for a key role of lipoprotein lipase in regulating adipose tissue growth in broilers. They also demonstrate that although the abdominal fat pad has been used in a number of studies of adipose tissue metabolism it is not necessarily representative of other depots.