No correlation between the growth of in vitro cultured Yucca valida clones and the growth of their mother plants in the field

Yucca valida is a close relative to Yucca schidigera and a potential alternative source of the steroidal saponins extracted from the tissues of the latter. The exploitation from the wild is not only inefficient but endangers the natural populations and an alternative to these would be their domestication and establishment of commercial plantations. Both species have a long life span cycle and low growth rates affected by environmental conditions that make it difficult to select fast growing, high yield elite individuals for cloning purposes. Here, we report the in vitro establishment and propagation of mature Y. valida plants derived from seed that showed very different growth rates in an experimental field and their propagative and growth characteristics in vitro. No correlation was found between the growth of field cultivated plants and the relative increase of fresh (FW) or dry weight (DW) of in vitro cultured plants.     

The occurrence and identification of <Emphasis Type="Italic">Setaria italica</Emphasis> (L.) P. Beauv. (foxtail millet) grains from the Chengtoushan site (ca. 5800 cal B.P.) in central China,with reference to the domestication centre in Asia

Archaeobotanical remains of Setaria grains and chaff were found at the Chengtoushan site in south-central China (ca. 5800 cal b.p.). Grain shape was determined, using length to breadth ratios, and morphological variation in the upper lemma of modern domesticated and wild Setaria species were examined using scanning electron microscopy as a basis for identifying archaeobotanical remains. Grains of S. viridis, S. yunnanensis, and S.×pycnocoma are slender, whereas S. italica, S. italica var. germinica, S. lutescenes, S. faberi, S. glauca, S. pallidefusca and S. intermedia are round in shape. The papillae distributed on the upper lemma of S. italica are small (8–15 μm) with a non-ridged base, while other Setaria species have large papillae (15–20 μm) with a widely ridged base. The remains of the Setaria from the Neolithic layers at Chengtoushan included S. italica, based on these identification characters. These new finds of foxtail millet are the earliest discoveries from the Yangtze River basin of southern China and are also the earliest evidence for co-cultivation of foxtail millet with rice. The implications of these findings for understanding foxtail millet domestication centres are discussed.     

鲥鱼的驯养与生物学研究Ⅲ.1龄鲥鱼的驯养及其生长规律

对池塘条件下 1龄鲥鱼不同方式的驯养试验表明 ,1龄鲥鱼生长较快 ,月均体长增加 1 8.1 9mm ,体重增加 2 4 .0 9g ;生长指标随季节和水温而变化 ,以初夏和秋末平均水温 2 9～ 30℃时生长较快 ;生长与池塘浮游生物量呈显著正相关 .1龄鲥鱼经 8个月套养 ,体重平均达 496.3g ;以施肥和投饲为主的精养试验 ,产量分别达 1 1 70和 1 0 87.5kg·hm- 2 ,个体均重达 2 0 3.3和 2 0 1 .3g .试验表明 ,鲥鱼池塘人工养殖是可行的     

Trees,soils, and food security

Trees have a different impact on soil properties than annual crops, because of their longer residence time, larger biomass accumulation, and longer-lasting, more extensive root systems. In natural forests nutrients are efficiently cycled with very small inputs and outputs from the system. In most agricultural systems the opposite happens. Agroforestry encompasses the continuum between these extremes, and emerging hard data is showing that successful agroforestry systems increase nutrient inputs, enhance internal flows, decrease nutrient losses and provide environmental benefits: when the competition for growth resources between the tree and the crop component is well managed. The three main determinants for overcoming rural poverty in Africa are (i) reversing soil fertility depletion, (ii) intensifying and diversifying land use with high-value products, and (iii) providing an enabling policy environment for the smallholder farming sector. Agroforestry practices can improve food production in a sustainable way through their contribution to soil fertility replenishment. The use of organic inputs as a source of biologically-fixed nitrogen, together with deep nitrate that is captured by trees, plays a major role in nitrogen replenishment. The combination of commercial phosphorus fertilizers with available organic resources may be the key to increasing and sustaining phosphorus capital. High-value trees, ''Cinderella'' species, can fit in specific niches on farms, thereby making the system ecologically stable and more rewarding economically, in addition to diversifying and increasing rural incomes and improving food security. In the most heavily populated areas of East Africa, where farm size is extremely small, the number of trees on farms is increasing as farmers seek to reduce labour demands, compatible with the drift of some members of the family into the towns to earn off-farm income. Contrary to the concept that population pressure promotes deforestation, there is evidence that demonstrates that there are conditions under which increasing tree planting is occurring on farms in the tropics through successful agroforestry as human population density increases. <br>     

Tolerance to herbivory by a stemboring caterpillar in architecturally distinct maizes and wild relatives

In a screenhouse experiment in southwest Mexico, we infested two maize cultivars, a land-race and a modern high-yielding variety, and two wild teosintes, Zea diploperennis and Zea mays parviglumis, with newly hatched larvae of the stemborer, Diatraea grandiosella. While subsequent damage levels, when corrected for differences in plant size, were highest in the wild perennial, Zea diploperennis, this taxon showed the lowest absolute and proportional reductions in growth and reproduction, i.e., it was most tolerant to the damage. Higher growth rates were not associated with tolerance. Rather, a greater number of tillers and leaves in the wild taxa allowed for compartmentalization of damage and greater developmental plasticity. These results, when combined with previous findings on effective defense patterns, indicate that tolerance in maizes and wild relatives may be positively associated with defense against stemboring by the same insect. Because the probable mechanisms for defense (tissue fiber) and tolerance (plant architecture) are unrelated, a positive association is contrary to the predictions of some optimal defense theories, which posit a negative relationship between tolerance and defense.     

鲥鱼的驯养与生物学研究Ⅱ.池养鲥鱼的生长特性及其与温度的关系

研究了池养鲥鱼生长特征,结果表明,其生长速度随季节和水温而变化,以９月中旬至１１月中旬和５月中旬至７月中旬生长较快,适宜生长水温为２５－３０℃。应用ＶｏｎＢｅｒｔａｌａｎｆｆｙ方程求得体长、体重生长方程Ｌｔ＝５１８．９５〔１－ｅ＾－０．３７５１（５－０．８７６３）〕,Ｗｔ＝２２０５．５〔１－ｅ＾－０．３７５１（ｔ－０．８７６３）〕＾３,体重生长拐点位于２．８０５３处,属性成熟拐点,其生长速度和加速     

Enzyme diversity in pearl millet (Pennisetum glaucum)

Summary Polymorphism in twelve genes coding for eight enzymes in pearl millet (Pennisetum glaucum (L.) R. Br.): alcohol dehydrogenases (ADH), catalases (CAT), -esterases (EST), glutamate oxaloacetate transaminases (GOT), malate dehydrogenases (MDH), 6-Phosphogluconate dehydrogenases (PGD), phosphoglucoisomerases (PGI) and phosphoglucomutases (PGM), was observed by electrophoresis on 74 cultivated samples and 8 wild samples from West Africa. Six genes: Est A, Adh A, Pgm A, Cat A, Pgi A, Pgd A contain 95% of the total variation. Principal component analyses and discriminant analyses of the 82 samples described by 46 allelic frequencies showed an almost complete separation into 3 groups: wilds, early maturing cultivars and late maturing cultivars. The early group has the highest enzyme diversity, with cultivated millets from Niger showing the most diversity. The high diversity of the early group and its extensive divergence from West-African wild millets suggest, firstly, the existence, elsewhere in Africa of other enzymatically different sources of wild millet, and secondly, the occurrence, prehistorically, of several different domestications. The late group of cultivars has the lowest variability and a relatively low coefficient of differentiation. This relatively homogeneous enzyme structure does not seem to be associated to ecology. A hypothesis is advanced suggesting that West African late-cultivars were derived from a common cultivated early complex. This complex must have been distributed across the Sudanian zone and must have been later sumitted to modifications by limited gene flow with local early maturing cultivars.     

CHINA AS A CENTER FOR EARLY ANIMAL DOMESTICATION

The paleontological as well as the archeological record in China is unique in that there is adequate evidence of hominid association with most of the animals that we know today as domesticates beginning at very early dates. During the last few years advances have been made with studies of the dog, horse, camel,water buffalo, cattle,yak,sheep, goat, pig, and chicken in China. One drawback is that by the time most domestic animals can be dated by recorded history they are quite advanced as domesticates and are quite similar osteologicaly to their modern counterparts.     

Collapse of species boundaries in the wild potatoSolanum brevicaule complex (Solanaceae, S. sect.Petota): Molecular data

TheSolanum brevicaule complex is a group of morphologically very similar wild and cultivated potato taxa (Solanum sect.Petota). This study uses single to low-copy nuclear RFLPs and RAPDs to investigate their species boundaries and relationships. Cladistic analyses of both data sets are largely concordant with each other and with a recently published phenetic analyses of the same accessions using morphology. All three data sets separate members of the complex into populations from Peru and immediately adjacent northwestern Bolivia, including most cultivated species accessions, and populations from northwestern Bolivia to Argentina. The molecular results suggest that the complex is paraphyletic as currently circumscribed. Many species of theS. brevicaule complex should be relegated to synonymy.