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61.
Youji Wang Menghong Hu Weimin Wang Ling Cao Yi Yang Biping Lü Rongrong Yao 《Aquaculture International》2008,16(6):539-549
The diel feeding rhythm and ontogenesis during early life stage of loach Misgurnus anguillicaudatus were investigated under experimental conditions (light: L 06:00–18:00, D 18:00–06:00 h). Morphological and behavioral developments
of loach from newly hatched to 40 days after hatching were observed. Larvae were able to prey on daphnia 3–4 days after hatching
at 23 ± 0.5°C. As the larvae grew, they showed an increasing feeding capacity and a distinct feeding rhythm. Feeding intensity
and incidence for day-4 larvae were highest at 10:00 and 16:00 h. The highest levels of feeding intensity for day-12 larvae
occurred at 08:00, 12:00, and 18:00 h as did feeding incidence. By day 20, when the larvae metamorphosed, the highest levels
of feeding intensity occurred at 06:00, 18:00, and 24:00 h and were concurrent with the highest feeding incidence. After metamorphosis,
feeding capacity had again increased considerably and, in contrast to the earlier stages before day 20, feeding intensity
for day-30 juveniles peaked at 05:00 and 20:00 h, about 1–2 h after the maximum feeding incidence. The feeding rhythm of loach
juveniles at day 40 was almost the same as the day-30 juveniles. The estimated maximum daily feeding rates were 43.1%, 33.4%,
19.0%, 12.8%, and 5.8% of body weight on days 4, 12, 20, 30, and 40, respectively. Thus, loach was found to have different
feeding rhythms in the pre- and post-metamorphosis stages, with the highest feeding activity in daytime during the larval
planktonic stage before metamorphosis, and intensely nocturnal feeding behavior during the juvenile benthic stage after metamorphosis. 相似文献
62.
《Plant Production Science》2013,16(3):299-305
AbstractThe difference in the number of pollen grains may be the primary factor determining the resistance to cool weather at the young microspore stage in rice (Oryza sativa L.) cultivars. To confirm this hypothesis, we compared the number of pollen grains among the cultivars or lines with various cool-weather resistance. The cultivars or lines used in the experiments were mainly released or grown in the Tohoku district (the northern part of the mainland of Japan). The number of pollen grains showed high correlation with the degree of cool-weather resistance, but considerably varied with the cultivar or line, even in the group having the same cool-weather resistance. Each group with different cool-weather resistance was divided into two subgroups, implying the existence of another genetic factor determining the resistance. The number of pollen grains in the plants cooled at the young microspore stage showed higher correlation with the degree of the cool-weather resistance than that in the control plants without exposure to low temperature. The correlation between the pollen number and spikelet sterility was also analyzed using the data of Satake and Shibata (1992, Jpn. J. Crop Sci. 61 :454–462), who primarily used the cultivars in Hokkaido (the northernmost island of Japan). The results were basically the same as those obtained in the present experiments. These results confirmed the hypothesis that the variation in the number of pollen grains is a primary factor of the resistance to cool weather at the booting stage in the cultivars in the northern part of Japan. The results also suggested the existence of another genetic factor determining the resistance. 相似文献
63.
64.
从全国主要油菜育种单位引进11个优质双低杂交油菜组合,顺序排列,两次重复,鉴定其适应性、丰产性、稳产性和轻简(机播机收)高效栽培性状。结果表明:高产品种应筛选R0701,实收单产2 812.5 kg/hm2为最高,且抗倒、抗病虫、抗旱、抗渍,长势长相等综合性状较优;早熟品种应选择宁杂11号,该品种熟期较CK提前6 d,产量2 672.3 kg/hm2,在4个早熟品种中最高,且生育的一致性、抗逆性等综合性状均较好,成熟期集中,耐裂荚,株型适于机械收割,是当今轻简高效栽培的理想品种。 相似文献
65.
The effect of maturity at harvest of whole-crop barley for ensiling on intake and liveweight gain of dairy steers differing in initial live weight (LW) was evaluated in an experiment over two years. Light (104–120 kg) and heavy (402–419 kg) dairy steers were fed diets containing predominantly whole-crop barley silage harvested at the milk stage [dry matter (DM) content of 284 g kg−1 and neutral-detergent fibre (NDF) concentration of 526 g kg−1 DM] or the dough stage of maturity (DM content of 328 g kg−1 and NDF concentration of 445 g kg−1 DM) and supplemented with up to 1 kg of concentrate. Dry matter intake (g kg−1 LW) was higher for whole-crop barley harvested at the dough stage than at the milk stage of maturity and the difference was greater in heavy than in light steers ( P < 0·001). Liveweight gain was higher and feed conversion ratio was lower for dough-stage compared with milk-stage silage ( P < 0·05) but there was no interaction with size of steer. Whole-crop barley harvested at the dough stage of maturity promoted higher liveweight gains in dairy steers compared with whole-crop barley harvested at the milk stage due to a higher DM intake. 相似文献
66.
家蚕胚胎伴性温敏性的遗传研究 总被引:6,自引:1,他引:5
试验用新九与伴1等4个温敏性的品种杂交,将其F1代蚕种用高温干燥条件催青,结果雄蚕正常孵化,雌蚕几乎不孵化,表明伴1等品种具有控制催青温敏性表达的基因存在。用华1与伴1组配的F1、F2及F1与亲本回交的14个组合作遗传分析,认为催青敏感性状由位于Z性染色体上的一个主基因控制,呈隐性的伴性遗传。 相似文献
67.
69.
空气湿度对澳洲坚果开花座果和果实生长的影响 总被引:4,自引:0,他引:4
花期的澳洲坚果植株随着空气湿度的降低,其花粉育性降低、座果率及光合产物(叶绿素含量、总糖含量和淀粉含量)下降、幼果生长速度减慢。试验结果表明:空气湿度的降低导致叶片光合作用能力下降,干物质积累少,生物产量降低,花粉萌发率低、花粉管生长速度慢,造成花期不遇、授粉受精不良、座果率低,最后造成产量降低。不同品种受空气湿度胁迫的影响程度不同,品种的内部生理特性、花粉育性以及产量都存在差异。澳洲坚果生长的适宜空气湿度为日平均空气湿度在50%以上。 相似文献
70.