Allelopathy of Ricinus communis and light spectrum variation decrease emergence and growth of Cyperus rotundus

Weeds negatively influence agricultural production. However, those losses depend on weed specie, its time of emergence, and period of interference on agricultural crops. Synthetic herbicides are commonly used to control these plants species; however, they may cause damage to the environment, human beings and animals health, and this problem justify the need to develop alternative bioherbicides. To evaluate the allelopathic potential of Ricinus communis (Castor bean) and light spectrum variation on the emergence and growth of Cyperus rotundus L., a trial was carried out in a protected environment with 15% of brightness reduction at the Center for Agricultural and Environmental Sciences at the Paraíba State University. Four aqueous extract concentrations of R. communis leaves were tested (0, 5, 10, and 15%) and four light spectrums variations (white, purple, blue, and red lights). Variables such as emergence, length, dry matter accumulation and growth rates of shoots and root of C. rotundus seedlings were assessed. Data were analyzed by normality test, analysis of variance, polynomial regression, and averages test. Soot and root emergence, length, and dry matter accumulation of C. rotundus seedlings were reduced due to the allelopathy caused by R. communis aqueous extract leaves (15% concentration) and under purple or red light spectrum radiation.

Experimental Study on Anti-inflammatory, Diuretic Effect and Acute Toxicity of Herb of Lanceolate Sedge / 世界科学技术-中医药现代化

This study was aimed to investigate the anti-inflammatory, diuretic effect and acute toxicity of Herb of Lanceolate Sedge. The mice were randomly divided into 5 groups, which were the physiological saline group, aspirin group (0.05 g·kg-1), high dose (HD), middle dose (MD) and low dose (LD) of water extract of Herb of Lanceolate Sedge (10, 5, 2.5 g crude drug per kg) group. Intragastric administration of medication was given to mice once a day for 3 days. Auricular swelling induced by dimethyl benzene was used in the model establishment to calculate the swollen ear degree and the swollen inhibiting rate. And rats were randomly divided into 5 groups, which were the physiological saline group, aspirin group (0.05 g·kg-1), high dose (HD), middle dose (MD) and low dose (LD) of wa-ter extract of Herb of Lanceolate Sedge (10, 5, 2.5 g crude drug per kg) group. Intragastric administration of medi-cation was given to rats once a day for 5 days. Carrageenan induced paw edema was used in the model establishment to calculate the paw swollen rate. And rats were randomly divided into 5 groups, which were the physiological saline group, Furosemide tablets group (0.01 g·kg-1), high dose (HD), middle dose (MD) and low dose (LD) of water extract of Herb of Lanceolate Sedge (10, 5, 2.5 g crude drug per kg) group. Intragastric administration of medication was giv-en to rats once a day for 5 days. Water-loaded was used in the model establishment to calculate the 5-hour urine amount. The maximum tolerance dose (MTD) was used in the determination of the acute toxicity. The results showed that the three groups of HD, MD and LD of water extract of Herb of Lanceolate Sedge had obvious inhibiting effects on the swollen ear degree and the swollen inhibiting rate among mice, and the paw swollen rate of rats. It had signif-icant increasing effect on the 5-hour urine amount. The MTD of intragastric administration of water extract of Herb of Lanceolate Sedge was 640 g crude drug per kg for mice. It was concluded that Herb of Lanceolate Sedge dis-played obvious effects on anti-inflammatory and dieresis with low acute toxicity.

Propriedades enzimáticas da enzima ALS de Cyperus difformis e mecanismo de resistência da espécie ao herbicida pyrazosulfuron-ethyl / Enzymatic properties of Cyperus difformis ALS enzyme and mechanism resistance of the species to pyrazosulfuron-ethyl herbicide

Cyperus difformis L. é uma planta daninha ocorrente em lavouras de arroz irrigado, que tem apresentado dificuldade de controle devido à resistência a herbicidas inibidores da enzima ALS. Os objetivos deste trabalho foram investigar características cinéticas da enzima ALS de biótipos de C. difformis e determinar as bases bioquímicas da resistência da espécie ao herbicida pyrazosulfuron-ethyl. Para isso, foram conduzidos experimentos em laboratório do BIOAGRO/UFV. O método utilizado baseou-se na metologia utilizada por CAREY et al. (1997) e adaptada por VARGAS et al. (1999), com algumas modificações. Foram avaliadas a concentração de substrato (piruvato) que fornece velocidade inicial igual à metade da velocidade máxima de reação (K M) e velocidade máxima de reação (Vmáx), bem como a atividade da enzima ALS na presença do inibidor (pyrazosulfuron-ethyl). Diante dos resultados, pode-se observar que a resistência de C. difformis a pyrazosulfuron-ethyl é decorrente da insensibilidade da enzima ALS ao herbicida, não acarretando, porém, prejuízo aos parâmetros cinéticos K M e Vmáx da enzima ALS.

Cyperus difformis L. is a weed that occurs in flooded rice, which has presented difficulty in controlling due to the resistance to ALS inhibiting herbicides. The objectives of this research were to investigate kinetic characteristics of ALS enzyme from C. difformis biotypes and to determine the biochemical bases of resistance from the species to pyrazosulfuron-ethyl herbicide. For that, experiments were conducted at the BIOAGRO/UFV laboratory. The method used was based on the methodology used by CAREY et al. (1997) and adapted by VARGAS et al. (1999), with some modifications. It was evaluated substratum concentration (pyruvate) that provides initial velocity equal to half the speed reaction (K M) and maximum velocity of reaction (Vmáx), as well the activity of the ALS enzyme in the presence of the inhibitor (pyrazosulfuron-ethyl). According to the results, it is possible to observe that C. difformis resistance to pyrazosulfuron-ethyl is due to the insensibility of the ALS enzyme to the herbicide, however without penalty to K M and Vmáx kinetic parameters of the ALS enzyme.