Bud set and autumn coloration of Larix sibirica and Larix gmelinii provenances in a field trial in southern Finland

The main aim of this study was to analyse the differences in the bud set, autumn coloration and needle shedding of seedlings in 20 Russian larch provenances and five comparison entries in field conditions in southern Finland over two growing seasons. Furthermore, it was studied if the differences could be explained by the geographic and climatic conditions of the provenance origins. We found that the provenances from cold northern climates developed both their terminal buds first and formed autumn colour as well as shed their needles much earlier than southern provenances. The timing of the bud set occurred earlier in 2008 compared to 2009, which was probably caused by lower than average temperatures in July and August of 2008. Thus, in addition to photoperiod, temperature also seemed to affect the bud set. The southern Dahurian larch provenances were able to utilise the length of the growing season the most effectively. The climatic adaptation, growth and properties of the provenances should be, however, studied over a longer time period. Therefore, currently used Raivola origin is still the safest choice for larch forestry in Finland.     

蒲公英和车前草在山东境内的春季物候特征及对气候变化的响应

基于2000-2015年山东省对蒲公英和车前草物候及气象观测资料,利用正交经验函数、相关分析、偏最小二乘回归研究了蒲公英及车前草在山东境内的春季物候变化特征及其对气候变化的响应规律。结果表明：1）2000-2015年蒲公英与车前草春季萌动与展叶总体表现为推迟的趋势且半岛沿海站点表现更明显,开花始期的年际变化具有局地性。2）冬季平均气温、2月平均气温升高会极显著促进两种植物的萌动、展叶。1月累积降水量与两种植物的萌动、展叶、开花始期总体显著负相关。鲁东地区两种草本植物的萌动、展叶与冬季日照时长显著负相关。在开花始期,除了冬季热量累积之外,从鲁东到鲁西3月平均气温及活动积温的影响逐渐加强,车前草表现更为明显。3）蒲公英与车前草偏最小二乘物候回归模型拟合结果表明,在萌动、展叶始期,2月平均气温、冬季平均气温、冬季0 cm平均地表温度、冬季正积温VIP值均大于1。在开花始期, 3月平均气温、3月活动积温、冬季平均气温、冬季0 cm平均地表温度在所有地区VIP值均大于1。     

Intrinsic earliness and basic development rate assessed for their response to temperature in wheat

The related concepts of basic vegetative period, intrinsic earliness and basic development rate in wheat are examined. These concepts have the common assumption that, if plants are vernalised fully and then grown at long daylength in order to remove any responses to vernalisation and photoperiod, the calendar or thermal time then taken to anthesis will be a characteristic of a genotype that will be heritable. Thus, regardless of temperature, early genotypes will always be earlier than late genotypes (providing there are no vernalisation and photoperiod responses).Using four genotypes, exposed to 50 days of vernalisation, and then grown at 18 h photoperiod under six temperature regimes ranging between 10 and 25°C, it is shown that; (1) no genotype had an absolute basic period as, depending on temperature, durations to anthesis for any one genotype varied by more than 50 days; (2) no genotype had an absolute value for intrinsic earliness (to anthesis), ranging for any genotype by more than 300°Cd depending on temperature; (3) basic development rate was not a single value for a genotype but varied with stage of development; (4) some genotypes changed their ranking for earliness depending on the temperature regime; and (5) genotypes were differentially sensitive to temperature for the subphases prior to anthesis.     

Genetic improvement of yield responsiveness to nitrogen fertilization and its physiological determinants in barley

Traditionally, barley in Argentina has been cultivated in low-yielding environments. A study was conducted to test whether breeding for improved performance under these conditions would have also improved the responsiveness to nitrogen availability. Four cultivars of two-rowed malting barley (released in 1944, 1960,1982 and 1998) were grown under 4 rates of nitrogen fertilizer at sowing (20, 50, 110and 160 kgN ha^-1). All cultivars increased their yield with the increase in soil nitrogen. But yield of modern cultivars responded more strongly than yield of old ones. For modern cultivars, increase in grain yield was of 12 ± 0.6 kgha^-1 for each 10 kg ha^-1 of increase in the mean yield (environmental index). Absolute values of genetic gain were related to nitrogen availability: 1.59, 2.58, 4.52 and 4.29 g m^-2 year^-1 for the N₂₀, N₅₀, N₁₁₀ and N₁₆₀ treatments, respectively. Grain yield was associated with grain number m^-2, which was dependent on spikes m^-2 and grains spike^-1. Total biomass at maturity also explained the changes in yield. It is concluded that selection under stress conditions was, in this case, beneficial to identify cultivars with high yields under a wide range of nitrogen availabilities. This revised version was published online in July 2006 with corrections to the Cover Date.     

Agro-morphological characterisation of common vetch and its close relatives

The Vicia sativa aggregate, which includes the common vetch, is a complex of six closely related tax a which combines cultivated, weedy and wild forms. In this study 454 accessions with an emphasis on Mediterranean and Central Asian accessions have been compared for 22 key agro-morphological and phonological characters. The agronomic potential of the different members of the aggregate is assessed and useful variation existing in the collection is determined. Geographic patterns of the agronomic variation are studied to determine sources of useful variation. In both sub sp. cordata and sub sp. sativa accessions were found which had higher yields than the checks, consisting of three promising accessions. Sub sp. macrocarpa needs a longer growing season than the other tax a to reach its full potential. The other three tax a in the aggregate all had quite low yields. Important variation in shattering of pod sand in tolerance to moderate frost and resistance to the Sitona weevil was found in most subspecies of the aggregate. Variation in phenological characters appeared to be related to the latitude from which the accession was collected. This revised version was published online in July 2006 with corrections to the Cover Date.     

西南桦花序生长和开花物候特征

从花序、单株、林分水平上对广西靖西县的一个土石山生态交错区内不同立地条件下西南桦的开花物候进行了观察和比较。结果表明:西南桦雌、雄花序开花持续时间为2 3 d,同一植株相同部位的雌花序较雄花序晚开花约14 d;其单株开花持续时间为4 28 d,开花同步性指数为0.160 0.259,绝大多数植株的冠层开花顺序依次为下层、中层和上层,土山和石山立地间单株开花持续时间和开花同步性均差异不显著 (P＞0.05);在林分水平上,西南桦开花持续时间为40 58 d,两种立地间差异不显著。     

甘肃民勤荒漠区植物物候相的持续特征和组合特征

以民勤荒漠区1974年以来的36种植物的物候观测资料,运用物候频数的统计方法,划分5个物候相,分析物候相的持续特征和组合特征。结果表明:植物的活动期物候相持续日数平均为212天,绿色期物候相持续日数较长,花色期物候相持续日数最短;花色期、挂果期和绿色期3个物候相不同植物之间相互重叠;旱柳的活动期物候相最长,火炬树和芦苇的活动期物候相最短,胡杨和火炬树的绿色期物候相最短,芦苇的秋色期物候相最短;荒漠区不同植物的花色期以及挂果期差异很大。在花色期物候相中,开花始期较早的植物开花末期也相对较早。     

密花柽柳的两季开花结实及其生态意义

对分布于新疆荒漠地区的密花柽柳开花物候、传粉及结实特性进行了比较研究.结果表明:①密花柽柳一年有2个独立的花期--春花期和夏花期;春花花期短,仅为11 d,为集中开花模式;夏花花期长,为69d,但每天开花数量比春花期少,为持续开花模式.②春花和夏花都有自交亲和性,套袋实验表明,春花和夏花都能进行风媒传粉和虫媒传粉.③夏...     

Pigeon pea for fallow improvement in slash-and-burn systems in the hills of Laos?

Calliandra calothyrsus has been reported to have potential for agroforestry in the humid lowlands of West and Central Africa. Provenance evaluation of the species was initiated in Yaounde, Cameroon with the objective of identifying adapted provenances with desirable traits for inclusion in evaluation of the management of various agroforestry technologies being developed for the humid lowlands of the region. Fifteen provenance seed collections from Central America and southeast Asian sources were included in the trial. Results indicate that enormous genetic variation exists between these provenances. The highest yielding provenance produced 1.8 and 2.5 times, respectively, wood and leaf biomass compared to the lowest yielding provenance. Most of the provenances evaluated flowered during the first six months after establishment while all the provenances (15) flowered by the end of the first year. However, this initial flowering did not result in productive pod development and seed setting. Two years after planting, the trees were cut at a height of 0.05 m above ground level, and more than 80% of the stumps of all the provenances re-sprouted. Leaf nitrogen content ranged between 2.25% and 2.78% of dry weight. Six provenances had above average values in at least five of the six desirable traits considered i.e.: height, growth, stem development, leaf biomass, wood biomass, leaf litter productivity and total nitrogen content of leaves; these are recommended for further testing for inclusion in appropriate technologies for soil fertility improvement. This revised version was published online in June 2006 with corrections to the Cover Date.     

The weather determines the number of cases of tick paralysis in dogs and cats in eastern Australia,caused by Ixodes holocyclus,the eastern paralysis tick

We studied over 222,000 cases of emergency veterinary consultations in four regions along the eastern coast of Australia. We found that cases of tick paralysis (TP) caused by the eastern paralysis tick, Ixodes holocyclus, accounted for 7.5% of these cases: >16,000 cases. The season of TP and the number (prevalence) of TP cases varied among regions and over the years. Our study of the association between weather and (i) the start of the season of TP, and (ii) the number of TP cases revealed much about the intricate relationship between the weather and I. holocyclus. We studied the effect of the hypothetical availability of isoxazoline-containing tick-preventative medicines and found that an increase in the availability of these medicines had significantly contributed to the decrease in TP cases. We found that the weather in winter accounted for the time of the year the season of TP starts whereas the weather in summer accounted for the number of TP cases in the TP season. Last, through a study of the effects of shifts in the climate under four hypothetical scenarios (warmer/cooler and drier/wetter than average), we propose that the start of the season of TP depends on how soon the weather in winter becomes suitable for the activity (e.g. host-seeking) and the development of I. holocyclus nymphs, and that the number of TP cases during the TP season depends on how many engorged female ticks and their eggs survive during summer.