Effects of climate on different potato genotypes 1. Radiation interception, total and tuber dry matter production

In 11 field trials in Rwanda, Tunisia and The Netherlands, the total dry matter production and tuber dry matter production of eight potato cultivars were analysed in terms of radiation interception and radiation use efficiency. The variation in length of the growing season was the most important factor explaining the differences in both total and tuber dry matter production among cultivars and sites. Radiation interception was the most important factor because the radiation-use efficiency was negatively correlated with radiation intensity and the variation in harvest index was of minor importance. Variation in length of the growing season among sites was related to daylength and temperature, in that shorter days at emergence and higher temperatures throughout the season resulted in a shorter growth cycle. The extent of these effects differed among cultivars, and it was concluded that climatic effects on tuber dry matter production could be attributed to the effects of temperature and daylength on the length of the growth cycle.     

Optimizing the lighting regime for Alstroemeria with respect to photoperiod and fluence rates

The Alstroemeria cultivars Diamond, King Cardinal and Libelle were grown for 18 months under five lighting regimes with, and without, soil cooling. The aim was to optimize the daily investment of light energy from artificial sources with respect to photoperiod and photosynthetic fluence rates and to elucidate possible links between reactions to photoperiod and root-zone temperature. The more photons (photosynthetically active radiation, PAR) that were supplied to the plants per day (8, 11 and 13 mol m⁻²), the higher was the total production of flowering stems. The total yield from regimes with 13 mol m⁻² day⁻¹ was higher when the light was spread over 20 and 16 h compared to 12 h. In treatments with soil cooling, the plants flowered continuously under all combinations of photoperiods and photosynthetic fluence rates, and the summer and autumn recession in flower production that occurred for non-cooled ‘King Cardinal' and ‘Diamond' was the same under all lighting regimes. It is concluded that it might be more cost-effective to spread the daily investment of light over 20 rather than 16 or 12 h when the total energy budget and CO₂ costs are taken into consideration.     

小麦温光发育模型的研究

1981～1984年,选用代表不同生态类型的25个小麦品种,在大田进行分期播种.通过分析温光等主要生态因子与小麦生长发育的关系,建立了各品种主要发育阶段的温光模型:播种至出苗为G=104.4751/(T-1.1032),出苗至二棱、出苗至拔节为V=a+bG+cP_(t1),二棱至抽穗、拔节至抽穗为V=a+bT+cL.文中认为,播种至出苗的日数(G)既能反映当时的温度条件,又可表示萌发时的“田间春化效应”;温光积(Ptl)则给“温度与光照之间存在明显的互补作用”找到了量的表达基础;因此,建模时采用这两个变量,是很有意义的.     

Vernalization promotes flowering of a heat tolerant Calandrinia while long days replace vernalization for early flowering of Brunonia

The flowering responses of Brunonia australis (blue pincushion) and Calandrinia sp. to vernalization, photoperiod, temperature and plant age were investigated to provide a foundation for manipulating flowering in these potential potted plants. Plants were vernalized at 4.8 °C for 0, 3 or 6 weeks at the plant age of 1–4 or 8–14 leaves. Following vernalization, plants were grown at 25/10 or 35/20 °C (day/night) under short days (11 h, ambient daylight averaged 380 ± 44 μmol m⁻² s⁻¹) or long days (16 h) provided by an additional 5 h night break (21:00–2:00 h at <4.5 μmol m⁻² s⁻¹ from incandescent lamps), for 85 days. This is the first work to investigate flowering of these ornamental species. Both species showed enhanced flowering following vernalization and a quantitative requirement for long days. The reduction of the time until the first visible inflorescence (Brunonia) or flower (Calandrinia) buds by 8–13 days was affected by vernalization for 3 or 6 weeks, respectively. Long days were effective for reducing the time to first visible floral bud and increasing the number of inflorescence or flowers per plant for both species. For Brunonia, LDs replaced vernalization when applied to plants with 1–4 leaves. Raising temperature from 25/10 to 35/20 °C increased the number of flowers per plant of Calandrinia by 2–2.5-fold for plants with 1–4 or 8–14 leaves respectively.     

Effects of climate on different potato genotypes 2. Dry matter allocation and duration of the growth cycle

The total growth and tuber dry matter production of a potato crop are determined mainly by the duration of its growth cycle. This in turn depends on climate, cultivar and crop management. The influence of climate factors defining crop growth and its timing were analysed by dividing the growth cycle into three phases and relating the duration of these phases to temperature, daylength and radiation. The variation in the length of all three phases contributed to the variation in the duration of the growth cycle and thus to the variation in tuber dry matter production. The variation in the length of the first phase (between emergence and tuber initiation) was best explained by the meteorological variables observed. Both higher temperatures and shorter daylengths hastened development in this phase. The magnitude of their effects depended on cultivar. In the second phase, from tuber initiation to end of leaf growth, temperature and daylength had similar effects but they were less clear and the variation in duration of phase 2 could not be explained as well as variation in the duration of phase 1. The last phase, from the end of leaf growth to the end of crop growth, was shortened by high temperatures and high radiation. A small part of the variation in the duration of this phase was explained by these variables. At this level of crop analysis, the effect of climate on crop development was explained best for the first phase, which is the most important one in explaining the variation in ground cover duration and tuber dry matter production. Quantitative understanding of the processes involved is required to be able to explain the effect of climate during the various phases of the growth cycle.     

Phenotypes and the onset of competition in spring barley stands of one genotype: daylength and density effects on tillering

Understanding the genotype–environment interactions requires a distinction between two effects of the environment on plants of a given genotype: the achievement of growth throughout their whole life and the prior determination of their growth potentials. Spring barley seeds from the same seed lot were sown at the end of the winter at three altitudes: 320 m a.s.l. (end of February), 880 m (beginning of April) and 1120 m (beginning of May), and at the end of May at the lowest site, in sparse and dense stands with and without nitrogen fertilization. This experimental design in natural conditions gave differences in initial daylengths (12, 14 and more than 15 h) that must modify the growth potentials, and different levels of competition, acting on growth achievement. The tillering patterns were measured on individual plants. The tillers in the axils of the first and the second leaf were lacking on many plants growing in the long day treatments in the sparse stands, and this increased up to between 70 and 90% in the dense stands. This seems to be due to far-red signals on seedlings emerging in the conditions which induce the floral development, before any competition can occur. Afterwards, the cessation of tillering as a result of the onset of competition, was delayed markedly during stem elongation in the stands established with long daylengths. Such phenotypes showed strongly reduced growth potentials.     

水稻品种光温生态研究

本文应用早晚季稻共77个品种采取人工和自然光长共15级处理,除1981年中季种植外,于1980～1987年早晚两季种植合共进行8年17季试验。结果表明:品种对日长反应实际存在有早稻的无感与弱感,晚稻的强感与极强感共4个类型,按品种对光温联应可分为无感光、弱到中感温,弱感光、中感温,强感光、中感温和极强感光、中到强感温四个类型。同时建立了各代表类型品种最优回归方程式,极强感光型具有严格的出穗临界日长,超过此日长不能抽穗,强感光型品种则随着叶龄增大对日长要求放宽。     

小麦穗分化过程中的光温组合效应研究

在Ｃｏｎｖｉｒｏｎ生长箱控制条件下,利用６个来自不同生态区的春小麦品种,研究了４种光温组合下（高温长日,高温短日,低温长日,低温短日）穗人化期持续天数与积温的反应,结果表明,日照对缩短各穗分化期起主要作用。（２）温度对光周期反应有强烈的调节作用,主要表现,长日照下。高温加快生育进程,短日照下,高温使短日抑制穗分化效应更为显著,常导致幼穗中途死亡,低温虽然延缓了小麦的生育进程,但却可以减轻短日对穗分     

光温生态因子对冬小麦幼穗分化的影响研究

对不同播期3个不同生态类型冬小麦品种幼穗分化进程系统观察研究结果表明,单棱期和二棱期为冬小麦对光温最敏感时期,其他幼穗分化发育时期对光温的反应与品种生态类型有关;试验播期范围内光温生态因子对冬小麦幼穗发育进程的影响作用以温度为主;气候变暖下通过调整播种期可调控冬小麦的幼穗发育进程。