Growth responses of cereal crops to organic nitrogen in the field

Eleven rice varieties differing in grain size were grown under controlled environmental conditions during the grain-filling period. The grain weight of upper grains in a panicle was examined at successive stages of growth during the grain-filling period. The effect of temperature on the rate and the duration of the period of grain-filling was determined using Khao Lo, a large-grain variety, and Bom Dia, a small-grain variety. Both the grain-filling rate and duration of the period of grain-filling differed among rice varieties and were positively and significantly correlated with the grain size. The duration of the grain-filling period from flowering to the time when almost maximum grain weight was attained ranged from 12 days at 32/24°C in Bom Dia to 36 days at 20/12°C in Khao Lo. The grain-filling rate was low in small-grain varieties, and generally increased with increasing grain size.

By lowering the temperature, the grain-filling rate decreased, the duration of the grain-filling period increased but the grain weight was almost constant.

Weight per grain was closely correlated with hull size. No relationship was found between weight per grain and nitrogen percentage of brown rice.     

狼尾草典型生理生化特征对阿特拉津胁迫的响应

通过盆栽试验考察狼尾草生长(生物量及根冠比)及典型生理指标(叶绿素、丙二醛及脯氨酸含量)对不同浓度阿特拉津污染胁迫的响应规律.结果显示,高浓度阿特拉津胁迫下狼尾草生物量(≥ 100 mg·kg^-1)、根冠比(≥ 200 mg·kg^-1)两类生长指标与对照处理相比达到显著性抑制水平.阿特拉津胁迫(≤ 200 mg·kg^-1)对狼尾草叶片中叶绿素含量的影响较小,各污染处理样品叶绿素含量与对照组的差异不显著;阿特拉津污染胁迫水平达到100 mg·kg^-1时,狼尾草叶片中脯氨酸含量达到最大值(39.38 μg·kg^-1),同时丙二醛含量与对照处理相比呈现显著升高的趋势.上述结果表明:只有在较高浓度阿特拉津(≥ 100 mg·kg^-1)胁迫水平条件下,狼尾草典型生长及生理指标才逐渐受到极显著影响,从植物生长与生理角度揭示了狼尾草对阿特拉津具有较强的耐受能力.     

Evaluation of indices for identification of pearl millet cultivars adapted to stress and non-stress conditions

Pearl millet (Pennisetum glaucum) is cultivated across a wide range of environments ranging from extremely stressful to favourable. The objective of this research was to compare methods to identify productive cultivars for stress and non-stress conditions. Thirty pearl millet cultivars were evaluated at 22 locations that were grouped as stress, non-stress, or intermediate environments. Five selection indices viz., arithmetic mean (AM), geometric mean (GM), AM (standard units), stress susceptibility index (S) and drought response index (DRI) were calculated for each genotype to determine correlation between selection indices and yield under stress (Y_S), non-stress (Y_NS), and average conditions (Y_AV). Both cultivars and locations were significant sources of variation. Phenology of cultivars had different influence on yielding ability in contrasting environments. While earliness was advantageous for stress conditions, cultivars with longer duration tended to yield more under non-stress conditions. Y_S was only moderately determined by Y_NS. Both AM and GM were suitable indices for selection of cultivars that would perform well across stress, non-stress, and intermediate environments. Stress susceptibility index (S) was negatively correlated with Y_S (r=−0.62^**) but should only be used as a selection criterion in combination with yield under stress (Y_S) to identify cultivars adapted to stress environments. DRI was positively correlated with Y_S but had no association with Y_NS. Results indicated that DRI might be useful for identifying cultivars with high performance under stress particularly when days to flower differ considerably among test entries.     

Response of Stipa bungeana and Pennisetum flaccidum to urine of sheep in steppe grassland of north‐western China

Urine [12·3 g nitrogen (N) L^?1], collected from native Tan sheep in rangeland of the Loess Plateau in north‐western China, was applied to vegetation patches dominated by Stipa bungeana (C₃ grass) or Pennisetum flaccidum, (C₄ grass) at either 0, 1·0, 2·0 or 4·0 L urine m^?2 in early‐, mid‐, or late‐growing season, and herbage mass and tiller number per sample recorded, allowing calculation of the respective contributions of increases in tiller weight and tiller density to the response from N in urine. Such records were made three times in the growing season of application of urine, and at the end of the following growing season. Responses to urine were of the order of 1 and 5 kg herbage DM kg^?1 N applied for S. bungeana and P. flaccidum, respectively. Except for early‐season application, responses of S. bungeana were mainly expressed in the season following urine application whereas responses of P. flaccidum tended to be expressed within the year of urine application, although with a residual response in the following year. The general pattern was for a tiller density‐mediated response in the period immediately after application, followed later by a tiller weight‐mediated response. Taken together with other recent research, S. bungeana can be considered a stress‐tolerating species with a limited response to N application and P. flaccidum an opportunist species able to capitalize on increased N supply.     

Genetic diversity among pearl millet maintainers using microsatellite markers

Genetic diversity among 70 maintainers and two pollinators of sub-Saharan and Indian origin was studied for simple sequence repeat (SSR) loci using 34 primer pairs. A total of 213 alleles were detected with an average of 6.26 alleles per locus. Polymorphic information content (PIC) ranged from 0.05 to 0.96 with a mean of 0.58 for the SSR loci. Mean PIC across the linkage groups and number of alleles in dinucleotide motifs varied significantly. The lowest PIC (0.239) for linkage group 6 indicated comparatively conserved nature of this linkage group. Genetic similarity estimates ranged from 0.05 to 0.73 with an average value of 0.29. This indicated sufficient diversity among the maintainer and pollinator lines. The 72 lines fell in five clusters, and the clustering pattern corroborated with their pedigree and characteristic traits. Pollinator ICMR 356 was more diverse from the maintainer lines analysed, and can be a potential parent for pearl millet hybrid development.     

SPAD值与杂交狼尾草施氮水平和农艺性状的关系

采用盆栽试验探讨利用叶绿素计(Chlorophyll Meter SPAD-502)预测杂交狼尾草粗蛋白含量和牧草的施氮水平.试验设5个氮肥水平(纯氮量0,100,200,300,400k9/hm2)和3次重复,利用叶绿素计读取不同氮水平不同时期杂交狼尾草倒数第3片叶子的SPAD值,同时测定部分农艺性状和茎叶粗蛋白含量.结果表明,杂交狼尾草的SPAD值和粗蛋白含量是随着牧草的生长而逐渐降低,分蘖数、株高和生物产量随着牧草的生长而提高;杂交狼尾草的SPAD值与其施氮水平、分蘖数、株高、产量和茎叶粗蛋白含量都成正相关,与牧草的株高相关性最小且都不显著;与牧草的分蘖数和产量相关性大,接近或达显著水平:与牧草的茎叶粗蛋白含量相关性最大,均达显著或极显著水平.因此,利用SPAD值可用来预测杂交狼尾草茎叶粗蛋白含量,进而诊断杂交狼尾草的氮素营养水平,为牧草的合理施肥提供依据.     

热研4号王草的适应性及其在福建的推广应用

通过适应性研究,发现热研4号王草适合在福建地区生长。该草表现为产量高、生长快、营养品质高,适口性好等优点,表现出良好的生态适应性和经济价值,适宜福建地区在种草养畜、种草养鱼、养殖场污染治理、荒山生态恢复等方面推广应用。     

Heterosis in landrace-based topcross hybrids of pearl millet across arid environments

This study quantified the magnitude of heterosis in pearl millet (Pennisetum glaucum) topcross hybrids produced by crossing 16 diverse landraces and three high yielding open-pollinating varieties on two homozygous male-sterile lines. Hybrids and pollinators were grown in 12 year ×;location combinations in India that were grouped into three zones. Genetic components of variance quantifying the differences among these hybrids were estimated. The hybrids showed a conspicuous heterosis for grain yield, earliness and biomass yield but not for straw yield. The level and direction of heterosis for time to flowering depended strongly on the earliness of the male-sterile line. In the terminal drought stress zone hybrids made on the early maturing male-sterile line 843A had the highest level of heterosis for grain yield (88%). This was partly due to escape from terminal stress. In the other two zones the heterosis for grain yield was on average 30%. Heterosis for biomass yield and biomass yield per day was on average also positive in all three zones. For all traits, except time to flowering and biomass yield per day, pollinator effects were the only significant source of variation. Differences between hybrids were mostly caused by additive genetic effects. Significant amount of heterosis observed in landrace-based topcross hybrids for grain yield and other productivity-related traits suggested that substantial improvement in pearl millet productivity in and environments can be obtained by topcrossing locally adapted landraces on suitable male-sterile lines. This revised version was published online in July 2006 with corrections to the Cover Date.     

Feasibility of breeding male-sterile populations for use in developing interpopulation hybrids of pearl millet

Inter‐population hybrids of pearl millet, Pennisetum glaucum (L.) R. Br., have a substantial grain yield advantage over open‐pollinated varieties that makes them an appropriate and economically viable proposition for many African agricultural situations, provided that stable male‐sterile populations can be developed for use as seed parents. The objective of this research was to examine the feasibility of breeding stable male‐sterile populations, using the d₂ dwarf version of Nigerian Composite NCD₂ and the A₄ cytoplasmic‐nuclear male sterility system as a test case. Results showed that two cycles of recurrent selection for sterility maintenance ability led to the development of a fully effective maintainer version of NCD₂. There was no significant difference between the original C₀ cycle bulk and the C₃ cycle bulk (developed from the third and final cycle of recurrent selection) for grain yield and other agronomic traits. The male‐sterile population at the third backcross stage, developed from the maintainer version of NCD₂, had as high a level of stable male sterility as the A¹ system commercial inbred male‐sterile line 841A₁. Thus, it is concluded that with the use of the A₄ cytoplasmic male‐sterile system, it would be possible rapidly to develop a maintainer version of any population without detrimental effects on grain yield and agronomic traits. Male sterility of populations developed from these maintainers will be highly stable, paving the way for their effective utilization as seed parents in breeding inter‐population hybrids.     

草栽与木栽灵芝营养成分的比较分析

分析比较了象草（Pennisetum purpurenum）栽培灵芝与 椴树（Tilia tuan） 段木栽培灵芝的氨基酸、脂肪酸、微量元素含量。结果表明,象草栽培灵芝的营养成分接近甚至略高于段木培养的灵芝。