从“湖北光敏感核不育水稻”的未受精子房和花药培养出单倍体植株

采用10种诱导培养基,培养湖北光敏感核不育水稻农垦58品种的未受精子房和花药。共培养未受精子房2790个,获得胚囊愈伤组织17块,最高诱导频率达3.33%,其中2块分化出绿苗。培养花药16740个,获得花药愈伤组织15块,最高诱导频率为0.92%,其中3块分化出苗,2丛白苗,1株绿苗。胚囊植株和花粉植株经根尖染色体检查为单倍体,2n=x=12。实验证明,液体培养、2,4-D0.2-0.5 mg/1、低温预处理对诱导胚囊愈伤组织及花粉愈伤组织的形成具良好效果。     

用杀虫双大粒剂防治水稻二化螟和三化螟的研究

本文报告一种防治水稻螟虫的杀虫双新剂型和使用效果.含有效成份5%的杀虫双大粒剂,每公斤含2000粒左右,在每亩1—1.25公斤的用量下,药效显著优于六六六、呋喃丹及杀虫脒等残留和高毒性农药.处理一亩田只需数分钟.在七个县和四个农场共266440亩稻田的示范试验中,防治效果达84.5—100%.杀虫双在田水中扩散迅速,24小时内即可扩散分布到全田.持效期较长,可达两周之久.但在蝗虫已蛀入稻茎后施用大粒剂,有效施药期只有3—4天.本文对杀虫双大粒剂的使用技术进行了经济效益、社会效益和生态效益方面的评价.     

Airborne fungi in an Italian rice mill

Summary Studies employing volumetric spore trap (VSP) and gravity settling culture plates (GSC) were conducted in order to analyse the air spora of a rice mill at Pavia, Italy, from October-December 1988. Results revealed a variety of fungal spores belonging to different genera and including recognized rice pathogenic fungi. The most frequent genera by GSC method includedAcremonium, Alternaria, Aspergillus, Aureobasidium, Cladosporium, Epicoccum, Fusarium, Helminthosporium, Mucor, Nigrospora, Penicillium, Rhizopus, Trichoderma, Trichothecium, and some unidentified fungi. Environmental assessment of fungal spores by VSP revealed that the most prevalent fungi were:Alternaria, Cladosporium, Epicoccum, Helminthosporium, Nigrospora, Pyricularia, Tilletia and hyaline, dark and coloured types of ascospores and basidiospores. Airborne fungal spore concentrations were particularly high (5,000–6,000 spores/m³) in the rooms of the rice mill where the initial stages of rough rice transformation take place, and dropped to 2,500 spores/m³ in the last room, where workers are. During a temporary interruption of the working processes, air spora concentration dropped below 1,000 spores/m³.Cladosporium, Epicoccum andNigrospora spores were predominant in all subdivisions of the indoor environments of the rice mill.     

Antitumor effect of RBS (rice bran saccharide) on ENNG-induced carcinogenesis

We examined whether orally administered RBS (rice bran saccharide), prepared from rice bran by hot water extraction, increases immunocompetence, inhibits gastrointestinal carcinogenesis with N-ethyl-N-nitro-N-nitrosoguanidine (ENNG) or shows an antitumor effect. After the administration of RBS, phytohemagglutinin (PHA)- and pokeweed mitogen (PWM)-stimulated blastogenesis of lymphocytes derived from the mesenteric lymph nodes and peripheral blood was enhanced, and the helper/ suppressor T-cell ratio was elevated, and migration activity of peritoneal macrophages was also increased in rats treated continuously with ENNG. ENNG-induced gastrointestinal carcinomas were observed in 43% of those administered RBS (ENNG-RBS) as compared with 88% in the control (ENNG) and 94% in the prednisolone (PRD) group (ENNG-PRD). The 12-month survival rate of rats bearing gastrointestinal cancer was 58% in the ENNG-RBS group as compared with 25% in the ENNG group and 15% in the ENNG-PRD group. RBS prevented the reduction in immunocompetence in the course of carcinogenesis, suppressed carcinogenesis, and prolonged the survival of rats with gastrointestinal cancer. Antitumor activities of RBS are thought to be a kind of host mediated action. The growth inhibition ratio of transplantable ENNG-induced cancer in Wistar rats was 42.1% in the RBS and 51.8% in the 5-FU group. Since little is known about the potent antitumor activity of -glucan, it would be interesting to consider the relationship between the structure and the biological activities of polysaccharides.     

Correlation between cell wall extensibility and the content of diferulic and ferulic acids in cell walls of Oryza sativa coleoptiles grown under water and in air

Rice ( Oryza sativa L. cv. Sasanishiki) coleoptiles grown under water achieved greater length than those grown either in air or under water with constant air bubbling. The extensibility of cell walls in coleoptiles grown under water was larger than that in the other treatments. Per unit length of the coleoptile, the content of ferulic and diferulic acids ester-linked to hemicelluloses was higher in air and bubbling type coleoptiles than in water type ones. The extensibility of the coleoptile cell walls correlated with the content of diferulic acids per unit length and per hemicellulose, suggesting that the enhancement of the formation of diferulic acid bridges in hemicelluloses in air or under water with air bubbling makes the cell walls mechanically rigid; thereby inhibiting cell elongation in rice coleoptiles. In addition, the ratio of diferulic acid to ferulic acid was almost constant irrespective of coleoptile age, zone and growth conditions, suggesting that the feruloylation of hemicelluloses is rate-limiting in the formation of diferulic acid bridges in the cell walls of rice coleoptiles.     

Phosphorus availability under alley cropping and mulched and unmulched sole cropping systems in Costa Rica

Phosphorus availability was measured in soils under five cropping systems: alley cropping with Erythrina poeppigiana, alley cropping with Gliricidia sepium, sole cropping with Erythrina poeppigiana mulch applied, sole cropping with Gliricidia sepium mulch applied, sole cropping with no mulch. The following parameters were measured: 1) plant-available soil P assessed by P uptake of maize and bean bioassay plants; 2) phosphate desorbable by anion exchange resin; 3) adsorption of added P into isotopically exchangeable and non-exchangeable pools.In the bioassay, P uptake of beans declined in the order: mulched sole-cropped>unmulched sole-cropped>alley-cropped soils. For maize the relative uptake was: mulched sole-cropped>unmulched sole-cropped = alley-cropped soils. These results suggest trees had not incorporated a significant quantity of P into the system after seven years and, probably, there was a decrease in available soil P due to the sequestration of P in the tree biomass. Potentially resin-desorbable P was higher in alley-cropped and mulched sole-cropped soils than in unmulched sole-cropped soils. The adsorption and desorption of added P into and from exchangeable and non-exchangeable pools did not differ between alley-cropped and unmulched sole-cropped soils.Crop yield and crop N, P and K uptake were all higher in the alley crops than in the unmulched sole crop. The supply of P to the crop under alley cropping seems to be dependent on P cycled and released from the mulch. The P cycle in alley cropping appears to be self-sustaining at least under conditions of moderate P fertiliser input.     

Biology of nitrogen-fixing Rhizobacteria

In non-legumes associative nitrogen-fixing system, several genera of rhizobacteria have been reported. The object of this paper is to summarize the current understanding of how rhizobacteria adhere to the root surface of non-legumes especially rice and other cereal crops. Evidence for involvement of rice lectin in adhesion will be reviewed. An emphasis will be placed on theKlebsiella R15 ammonium assimilation system in free-living state and in associative state with rice seedlings. Nitrogenase and glutamine synthetase (GS) activities of associativeKlebsiella increased significantly in the rhizosphere of rice comparing to the free-living state. In rice, the soluble form of GS specific activity appear to be slightly lower than in rice root in the absence of bacteria. These results suggest that nitrogen-fixing activity has been enhanced during association. The dinitrogen fixed should be changed to amino acids via GS-GOGAT pathway in bacteria. Transfer of fixed nitrogen and assimilation in the rice plant is the problem that needs to be solved in order to improve the efficiency of associative nitrogen fixation.     

Carbon isotope composition of CH4 from rice paddies in Japan

Carbon isotope ratios (¹³C) for bubble CH₄ in a submerged paddy soil were studied in Yokohama, Japan, throughout a growing period, and its variation was found. Bubble CH₄ collected from other 33 paddy fields in Japan was also measured for its ¹³C and the results agreed with Yokohama. Furthermore, the variation occurred irrespective of the amount and the type of supplied organic substances to the fields (whole rice straw, rice stubble, or compost). The ¹³C value (average value of -55.9 ± 4.24) from these paddy fields was higher than those of the CH₄ emitted from African and North American paddies. The higher value was little affected by their difference in the supplied organic substances. CH₄ oxidation likely occurs for bubble CH₄ in the shallow paddy fields. A rough estimate of the total CH₄ production, using isotope mass balance, showed that 17 to 22% of organic carbon supplied to Japanese paddies transforms to CH₄.     

Alkaline phosphatase activities of anAnabaena sp. from deep-water rice

Anabaena sp. grew with mono- and di-ester phosphate compounds as sources of phosphate, indicating the presence of phosphomonoesterase (PMEase) and phosphodiesterase (PDEase) activities. Cell-bound PMEase and PDEase activities were detected during growth in 0.5 and 10 mg PO₄l^–1 only when the cellular phosphate concentration fell to 0.46% of cell protein and the activities increased as cellular phosphate content decreased. The K_m values for these enzymes were 0.3mm forp-nitrophenyl phosphate and 0.2mm for bis-p-nitrophenyl phosphate, respectively. Only PMEase activity was found extracellularly. The pH optima for PMEase and PDEase were 10.2 and 10.4, respectively, and the temperature optima at pH 10.2 were 37°C and 40°C, respectively. Ca²⁺ increased the enzyme activities while Zn²⁺ caused marked inhibition. The inorganic phosphate repressed the cellular PMEase activity after a lag of 4 h.     

越冬期间香蕉果穗套袋的防寒效果及其对产量的影响

冬季香蕉果穗用兰色聚乙烯薄膜套袋之后,可提高袋内温度1～5℃,果实低温伤害卑只有1％左右,而未经套袋的达23％～35％,果指长度和径围增加率分别达12％和9％左右,果实产量比对照增加8％～16％。试验结果表明,兰色聚乙烯薄膜套袋是越冬期间香蕉防寒保果和增产的一项有效措施。