Relationship between the morphogenesis of Italian ryegrass cv. 'BRS Ponteio' with forage and seed production / Relação entre as características morfogênicas do azevém anual cv. 'BRS Ponteio' com a produção de forragem e de sementes

This study aims to verify, accurate and precisely, the responses of Italian ryegrass 'BRS Ponteio' cultivar to different frequencies of defoliation for forage production and especially for seed production. For this purpose, a randomized block design experiment with four replications was conducted. Four frequencies of defoliation were applied (zero, one, two, and three) based on the thermal sum, evaluating the rate of leaf appearance (LAR), phyllochron (P), leaf expansion rate (LER), leaf senescence rate (LSR), stems expansion rate (SER), tillering rate (TR), leaf life span (LL), forage production, proportion of leaf blades, stems plus sheaths, senescent material, and inflorescences, as well as seed production. Second defoliation noticeably altered the morphogenic plant responses, reduced expansion rates and leaf appearance, increased rates of tillering and stems expansion. This phenotypic maintained a high seed production and provided a harvest of forage mass 100% higher than the collected mass in the first cutting. Third defoliation led to an increase of 100% of the harvested forage mass; however, it caused drastic and negative changes in the morphogenic characteristics and seed yielding.

O presente estudo teve o objetivo de verificar, de forma precisa e detalhada, as respostas da cultivar de azevém anual 'BRS Ponteio', às diferentes frequências de desfolha para a produção de forragem e de sementes. Realizou-se, para tanto, um experimento com delineamento de blocos casualizados com quatro repetições. Foram aplicadas quatro frequências de desfolhas (sem, uma, duas e três) baseando-se no acúmulo térmico, onde se avaliou a taxa de aparecimento de folhas (TApF), o filocrono (F), a taxa de expansão de folhas (TEF), taxa de senescência de folhas (TScF), taxa de expansão dos colmos (TEC), taxa de perfilhamento (TP), duração de vida da folha (DVF), produção de forragem, proporção de lâminas foliares, colmos mais bainhas, material senescente e inflorescências em cada tratamento, bem como a produção de sementes. A segunda desfolha alterou marcadamente as respostas morfogênicas da planta, reduziu as taxas de expansão e aparecimento de folhas e aumentou as taxas de perfilhamento e de expansão do colmo. Esta plasticidade fenotípica manteve a alta produção de sementes da planta e propiciou a colheita de massa de forragem 100% superior à massa colhida no primeiro corte. A terceira desfolha propiciou o aumento de 100% da massa de forragem colhida, todavia, promoveu alterações drásticas e negativas nas características morfogênicas e no rendimento de sementes.

Management of Asymptomatic Small Abdominal Aortic Aneurysm

PURPOSE: There have been controversies about the management of small abdominal aortic aneurysm (AAA). This prospective study was performed to analyze the annual expansion rates and the clinical courses of small AAAs, and to we wanted to suggest some guidelines for the proper management of small AAAs in Koreans. METHOD: From 1991 to 2003, thirty-five patients who had an initial diagnosis of small AAA were enrolled into the study group. All the patients were assigned to undergo regular imaging studies with either ultrasonography or CT angiography every 6 months. At the end of the study, the twenty four patients who were followed up with at least three successive visits were included in the statistical analysis. The clinical symptoms and the size of their aneurysms were documented on each visit. Symptomatic aneurysms and aneurysms with a size greater than 5.5 cm were considered as candidates for surgical repair. The annual expansion rate, rupture rate and the requirements for aneurysm repair were analyzed. The overall aneurysm expansion rate was 0.33+/-0.22 cm/year. RESULT: The expansion rate of the aneurysms smaller than 4.0 cm (12 cases) was 0.32+/-0.26 cm/year and that of aneurysms between 4.0 cm and 5.0 cm in size (12 cases) were 0.34+/-0.19 cm/year (P=0.55). Only the presence of iliac artery involvement was significantly related with a higher aneurysm expansion rate (0.47+/-0.2 cm/year vs. 0.19+/-0.13 cm/year, respectively, P=0.001). There was no rupture of aneurysm during the study. 10 cases undergone aneurysm repair and there was no morbidity or mortality after the aneurysm repair. CONCLUSION: Small AAAs in Koreans can be safely managed with regular follow-up. Closer follow-up is recommended as the aneurysm size increases and for small aneurysms that involve the iliac artery.

Natural History of Small Abdominal Aortic Aneurysms

The operative treatment of abdominal aortic aneurysm (AAA) is generally recommended in ruptured AAA, symptomatic or rapidly expanding AAA, complicated AAA and atypical aneurysms, but there is a controversy in treatment of asymptomatic small-sized AAA. To determine the proper management plan, it is important to know the natural history of AAA, expansion rate and frequency or pattern of complications. There are several reports about the natural history of AAA in western population, but little has been reported in Koreans. Authors performed this study in order to analyze the natural history of small AAA, and to establish a guideline in the proper management of small AAA. PATIENTS & METHODS: Since January 1991, among the patients diagnosed as AAA at Seoul National University Hospital, we followed 15 patients whose aneurysm size was less than 6 cm without operation. In this study, we analysed the natural history of 11 cases with more than 6 months follow up; occurrence of symptoms, physical examinations, and aneurysm size measurement by ultrasound or CT every 6 months. RESULTS: All 11 patients were men, and the mean age was 63.9 years, ranging 54 to 75 years. According to the measurement of largest transverse diameter, mean expansion rate for 6 months was 0.17 0.138 cm. Follow-up period ranged 6~84 months and the median duration was 30 months. Expansion rate according to the initial size was 0, 0.246, 0.178, 0.1 cm/6 months respectively in group A (4.0 cm; 1 case). There was no rupture, aneurysm-related complication, nor death during the follow-up period. We performed elective operations in 2 cases, first case due to aneurysmal expansion over 6 cm, and the other due to severe anxiety of the patient for rupture. CONCLUSIONS: It may be a safe treatment discipline to follow up small AAA patients with sono-guided size measurement and elective operation in selected cases.