赤霉菌的培養与赤霉素酸的提煉結晶

一、赤霉菌的生物学特征赤霉菌Gibberella fujikuroi又叫做稻惡苗病,日人謂之稻馬鹿苗病,是屬于真菌的子囊菌綱Asco-mycetes,以肉座菌目Hypocreales在所有栽培水稻的国家里都曾经报导过,是一种由土壤帶来的病害。我国裘潘氏曾于1939年在南京金陵学报首次报导过。初时研究者們以共有性世代——子囊体,名之为赤霉菌Gibberella fujikuroi,以其无性世代——分生孢子,謂珠鐮刀菌Fusarium monilifome,乃由于最初研究者观察时未能窺其全豹,各定一名所致。赤霉菌与其他子囊菌相似,营养体为茂盛分枝的菌丝(图1),菌丝具有横隔。

Study on Variation of Endogenous Hormones at the Germinating Stage of Tea Spring Shoot

An HPLC method was used to analyze the contents and variation of IAA,GA3,ABA.and ZT at five stages around the tea shoot germinating in spring.The contents of GAa and ABA had a top value during the winter and decreased with the growth of tea shoots,while the contents of IAA and ZT had a low value during the winter and increased quickly at the beginning of shoot growth,but soon afterwards increased slowly or decreased a little.The ratio of hormones was closely related to the growth of tea plant.The study indicated that the ratios of GA3 to ABA and IAA to ABA were at low values during the winter and went up with the shoot genninating.When the activity of roots was weak,the ratio of ZT to IAA had a top value,but went down gradually with luxuriant activity of roots.The ratio of GA3 to ZT had a certain relativity with the shoot genninating,which was at a top value during the winter but went down suddenly at the beginning of shoot genninating.

Importance of the Role of Gibberellic Acid and Potassium Nitrate in Seed Germination Habanero

The habanero chili （Capsicum chinense Jacq.） is a species of great demand in the domestic and international markets. One problem in the cultivation is low percentage of seed germination. There is little information on the use of promoters and imbibition time to increase this parameter, without compromising the quality of seedlings. In this context, authors assessed the independent effect of GAs （gibberellic acid） and KNOs at concentrations of 0, 100, 200, 300, 400 and 500 mg·L1. Seeds without preconditioning were the witness. The experimental unit was a Petri dish with 50 seeds on filter paper placed equidistant. There were three replicates per treatment and the experimental design was randomized complete block. Imbibition time was 24 h. The experimental units were kept in an incubator at 22 ± 2 ℃. From the time of planting and for periods of 24 h for 14 d, experimental units were reviewed to determine the time at the beginning of germination and the total cumulative percentage. The authors also determined the number of normal and abnormal seedlings, the length of hypocotyl and radicle, weight of fresh and dry matter of seedlings. On the fifth day after sowing in vitro, concentrations of 500 mg·L^-1 of GAs, 300 and 400 mg·L^-1 KNO3, increased 208% the percentage of seed germination of habanero chile. On day 14 after sowing in vitro concentrations of 500 mg·L^-1 GA3, 300 and 400 mg·L^-1 KNO3, increased 23% normal seedlings and 40% dry matter thereof, with respect to seeds obtained without preconditioning. Unconditioned seeds before sowing produced 125% more seedlings.

Drying temperature affects rice seed vigor via gibberellin,abscisic acid,and antioxidant enzyme metabolism

Seed vigor is a key factor affecti ng seed quality.The mechanical drying process exerts a sign ificant in fluence on rice seed vigor.The initial moisture con tent(IMC)and drying temperature are considered the main factors affecting rice seed vigor through mechanical drying.This study aimed to determine the optimum drying temperature for rice seeds according to the IMC,and elucidate the mechanisms mediating the effects of drying temperature and IMC on seed vigor.Rice seeds with three different IMCs(20%,25%,and 30%)were dried to the target moisture content(14%)at four different drying temperatures.The results showed that the drying temperature and IMC had significant effects on the drying performance and vigor of the rice seeds.The upper limits of drying temperature for rice seeds with 20%,25%,and 30%IMCs were 45,42,and 38°C,respectively.The drying rate and seed temperature increased sign ificantly with in creasing drying temperature.The drying temperature,drying rate,and seed temperature showed extremely significant negative correlations with germination energy(GE),germination rate,germination index(Gl),and vigor index(VI).A high IMC and drying temperature probably induced a massive accumulation of hydrogen peroxide(H2O2)and superoxide anions in the seeds,enhanced superoxide dismutase(SOD)and catalase(CAT)activity,and increased the abscisic acid(ABA)content.In the early stage of seed germination,the IMC and drying temperature regulated seed germination through the metabolism of H2O2,gibberellin acid(GA),ABA,and a-amylase.These results indicate that the metabolism of reactive oxygen species(ROS),antioxidant enzymes,GA,ABA,and a-amylase might be involved in the mediation of the effects of drying temperature on seed vigor.The results of this study provide a theoretical basis and technical guidance for the mechanical drying of rice seeds.