Sacred lotus (Nelumbo nucifera) has been cultivated as a crop in Asia for thousands of years. An ∼1300-yr-old lotus fruit, recovered from an originally cultivated but now dry lakebed in northeastern China, is the oldest germinated and directly (14)C-dated fruit known. In 1996, we traveled to the dry lake at Xipaozi Village, China, the source of the old viable fruits. We identified all of the landmarks recorded by botanist Ichiro Ohga some 80 yr ago when he first studied the deposit, but found that the fruits are now rare. We (1) cataloged a total of 60 lotus fruits; (2) germinated four fruits having physical ages of 200-500 yr by (14)C dating; (3) measured the rapid germination of the old fruits and the initially fast growth and short dormancy of their seedlings; (4) recorded abnormal phenotypes in their leaves, stalks, roots, and rhizomes; (5) determined γ-radiation of ∼2.0 mGy/yr in the lotus-bearing beds; and (6) measured stratigraphic sequences of the lakebed strata. The total γ-irradiation of the old fruits of 0.1-3 Gy (gray, the unit of absorbed dosage defined as 1 joule/kg; 1 Gy = 100 rad), evidently resulting in certain of the abnormal phenotypes noted in their seedlings, represents the longest natural radiobiology experiment yet recorded. Most of the lotus abnormalities resemble those of chronically irradiated plants exposed to much higher irradiances. Though the chronic exposure of the old fruits to low-dose γ-radiation may be responsible in part for the notably weak growth and mutant phenotypes of the seedlings, it has not affected seed viability. All seeds presumably repair cellular damage before germination. Understanding of repair mechanisms in the old lotus seeds may provide insight to the aging process applicable also to other organisms.

Root and butt rots are often implicated as causal factors influencing windfall and mortality of residual trees following partial cutting. Measurements of decay at stump level (i.e., the upward extension of root rot) were made on cross-sectional discs taken from windfallen and standing dead 100-to 130-year-old black spruce (Picea mariana (Mill.) BSP) near Nipigon in northwestern Ontario. Subsequently, causal fungi were identified using laboratory culturing procedures. The incidence and amount of decay in windfallen trees within leave strips following alternate strip clearcutting was higher than the general stand levels but lower than that found in windfallen trees in uncut forest. The incidence and amount of decay was also higher in windfallen trees near the centres of the leave strips than in those near the edges and corners of these strips. These results indicate a strong association between root rot and windfall and suggest that for comparable windfirmness, trees near the edges of residual stands must have less decay than those in more sheltered locations. Decay levels tended to be lower on poorly drained sites than on well-drained sites. In uncut forest, and especially in the leave strips, more trees were uprooted than died standing or suffered stem breakage. The incidence and amount of decay tended to be lower in uprooted trees than in standing dead trees or those with stem breakage, although in uncut forest virtually all windfallen or standing dead trees had some degree of stump-level decay. Of the 21 wood-rotting Basidiomycetes isolated from windfallen and standing dead trees, Inonotus tomentosus (Fr.:Fr.) Teng was the most frequent, followed in order by Armillaria ostoyae (Romagn.) Herink, Coniophora puteana (Schum.:Fr.) Karst., and Scytinostroma galactinum (Fr.) Donk. The incidence of I. tomentosus, C. puteana, Xeromphalina campanella (Batsch.:Fr.) Kuhner & Maire, and Serpula himantioides (Fr.:Fr.) Karst., but not Armillaria ostoyae, Scytinostroma galactinum, and Sistotrema brinkmanii (Bres.) Erik., was greater in windfallen and standing dead trees from the leave strips than in the general stand populations. In the leave strips, I. tomentosus, Amylostereum chailletii (Pers.:Fr.) Boid., and Trichaptum abietinum (Dickson:Fr.) Ryv. tended to greater relative abundance in standing dead trees, while the relative abundance of C. puteana and Serpula himantioides was greater in trees with stem breakage. Armillaria ostoyae and Scytinostroma galactinum were as abundant in uprooted trees as in standing dead trees or those with stem breakage. Ascocoryne sarcoides (Jacq.:Fr.) G. & W., a staining fungus that may protect against decay fungi, was frequently isolated in this study.Résumé : Les caries de souches et de racines sont souvent considérées comme des facteurs qui influencent le renversement et la mortalité des arbres résiduels suite à une coupe partielle. Des mesures de la carie dans la souche (i.e., l'extension de la carie de racine vers le haut) ont été prises sur des disques (section radiale) prélevés sur des ...

No abstract