Outdoor mass microalgae production in Bahia Kino, Sonora, NW Mexico

The diatom Chaetoceros muelleri was grown in outdoor mass cultures under the winter, spring and summer conditions of Bahia Kino, Sonora, NW Mexico. The solar irradiance in winter was close to 60% of that available in spring and summer, but the cell concentrations and the harvestable biomass were one order of magnitude higher in spring and summer than in winter. There was no difference between the biomass harvested after 2 and 3 days in winter and summer, whereas in spring it was higher after 3 days. The protein content was significantly lower in winter, and carbohydrates and lipids were higher in winter and spring. The number of cells and the amount of harvestable biomass of outdoor cultures of C. muelleri depend on the temperature prevailing in each season, which causes significant differences in growth rates and in biochemical composition.     

解析点在园林景观设计中的形式表达

点是现代景观设计中一个重要的视觉造型元素。现就景观设计中点的涵义、形态视觉特性等方面进行论述,并通过应用实例来阐述景观设计中点的几种表达方式,不同"点"的造型要素在不同应用情况下产生的不同景观效果。     

一种恢复渠道中线测量的快捷方法

渠道是农田水利建设的一个重要工程，渠道测量在渠道兴、改、扩建中具有重要的地位和作用。仅就施工过程中如何快捷恢复渠道中线的测量方法作了探讨，并对恢复中线的精度作了相应分析。     

几种新型农膜的小气候效应研究

研究了3种不同薄膜覆盖大棚内小气候因子的变化.研究结果表明,在不同测定日期中,覆盖不同塑料薄膜大棚的棚内外日平均气温和日平均地温变化相似,转光膜1的保温性能优于转光膜2和无滴膜;转光膜1的透光率高于转光膜2和无滴膜,无滴膜的透光率则略高于转光膜2.不论晴天还是阴天,转光膜,均表现出较好的保温与采光性能,而且使用这3种农膜后.大棚内温度和光强变化规律相似.     

不同穗型水稻群体中温湿度特征的研究

本研究以不同穗型的3个品种沈稻11、辽粳294和沈农9816为试材，研究了水稻群体间的温湿度特征。结果表明，白天不同品种水稻群体中温度和相对湿度的变化趋势与大气一致。水稻群体中露点温度的脉动远大于温度和相对湿度，总的趋势是中午露点温度较高。不同水稻群体中温度的差异小于湿度。从8月上旬至9月中旬，不同品种群体中的温、湿度差异逐渐增大，弯穗品种群体中的温度低于直立、半直立穗品种，湿度大于直立、半直立穗品种，直立和半直立穗品种之间的差别不太大。     

草地反射太阳光偏振特性测量个例分析

本文在中国科学院植的研究所岩石草原定位研究站对羊草和苔草样方进行太阳反射光偏振特性的测量。     

Light modulation of volatile organic compounds from petunia flowers and select fruits

Light intensity, duration, direction, and wavelength are informative to plants. The biochemical circuits that connect specific light wavelengths to expression of specific genes and the metabolic networks they govern have been well defined. However, little emphasis has been placed on how discrete wavelengths of light, alone or in combination, may be applied to manipulate postharvest qualities of high-value horticultural crops. Using narrow-bandwidth LED light we test the hypothesis that discrete light wavelengths can affect the accumulation of volatile compounds known to affect aroma or taste in select flower and fruit products. Volatile benzenoid/phenylpropanoid emission from petunia flowers could be altered with light application. Levels of a key floral volatile, 2-phenylethanol, increased with a red and far-red light treatment. Similar experiments demonstrated that fruit volatile profiles of tomato, strawberry, and blueberry can be manipulated with specific light treatments. These results suggest that compounds affecting sensory qualities of flowers and fruits can be modified by adjustment of ambient light conditions. These findings open new areas of inquiry about how the fragrance and flavor of flowers and fruits may be improved with simple changes in postharvest light conditions.     

Nitrate leaching in a silage maize field under different irrigation and nitrogen fertilizer rates

Quantification of the interactive effects of nitrogen (N) and water on nitrate (NO₃) loss provides an important insight for more effective N and water management. The goal of this study was to evaluate the effect of different irrigation and nitrogen fertilizer levels on nitrate-nitrogen (NO₃-N) leaching in a silage maize field. The experiment included four irrigation levels (0.7, 0.85, 1.0, and 1.13 of soil moisture depletion, SMD) and three N fertilization levels (0, 142, and 189 kg N ha⁻¹), with three replications. Ceramic suction cups were used to extract soil solution at 30 and 60 cm soil depths for all 36 experimental plots. Soil NO₃-N content of 0-30 and 30-60-cm layers were evaluated at planting and harvest maturity. Total N uptake (NU) by the crop was also determined. Maximum NO₃-N leaching out of the 60-cm soil layer was 8.43 kg N ha⁻¹, for the 142 kg N ha⁻¹ and over irrigation (1.13 SMD) treatment. The minimum and maximum seasonal average NO₃ concentration at the 60 cm depth was 46 and 138 mg l⁻¹, respectively. Based on our findings, it is possible to control NO₃ leaching out of the root zone during the growing season with a proper combination of irrigation and fertilizer management.     

遮荫处理对侧柏种子萌发的影响

在不同光照梯度55.44%自然全光照(Natural sonlight,NS)、21.12%NS、3.47%NS 和0.86%NS的人工遮荫条件下,研究了侧柏(Platycladus orientalis)种子萌发的特点.结果表明:4个光照梯度处理的侧柏种子的萌发率分别为68.9%、82.2%、44.4%和42.2%;随着光照强度的减弱,种子萌发进程减慢;萌发指数和幼苗活力指数均在21.12%NS处理最大,分别为1.89和770.8.     

Influence of light intensity on feeding, growth, and early survival of leopard coral grouper (Plectropomus leopardus) larvae under mass-scale rearing conditions

This study investigated the effect of different light intensities on feeding, growth and survival of early stage leopard coral grouper Plectropomus leopardus larvae. Four different light intensities (0, 500, 1000 and 3000 lx) were used and larvae were kept under constant light conditions from 0 day after hatching (DAH) to 5 DAH. The larvae were fed a small S-type of Thai strain rotifers at a density of 20 individuals/mL from 2 DAH. The number of rotifers in larval digestive organ and total length of larvae were examined at 3 h intervals between 04:00 and 22:00 h on 3 DAH, and thereafter at 6 h intervals until the end of the experiment (5 DAH). Four experimental trials of the larval rearing were repeated using by 60 kL mass-scale rearing tanks. The results indicate that coral grouper larvae are visual feeders and their food intake increases with increasing light intensity. Food intake of larvae reared at 3000 lx was significantly higher than those reared at 0–1000 lx on 3 DAH despite being the first-feeding day (P < 0.01). On 4 DAH, total length of larvae reared at 3000 lx was significantly larger than those reared at the lower light intensities (0, 500 and 1000 lx), and thereafter light intensity significantly influenced larval feeding and growth until the end of the experiment. Survival on 5 DAH did not show a significant difference between light intensities, but survival rate at 3000 lx and 1000 lx had a tendency to be higher than those reared at the lower light intensities (0 and 500 lx). In contrast, larvae reared at 0 lx exhibited stagnant and/or negative growth. These results indicate that light intensity is significantly the factor affecting larval feeding, growth, and survival in coral grouper larvae under the rearing conditions.