共查询到19条相似文献，搜索用时 312 毫秒
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1营养生长与生殖生长
农作物生长即包括营养体生长和生殖体生长。农作物营养器官根、茎、叶的生长称为营养生长。作物生殖器官花、果实、种子的生长称为生殖生长。营养生长和生殖生长以花芽分化为界限，把生长过程大致分为两段。花芽分化之前属于营养生长，之后则属于生殖生长期。但营养生长和生殖生长的划分并不是绝对的，因为作物从营养生长过渡到生殖生长之前，均有一段营养生长与生殖生长并进的阶段。 相似文献
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1植物生长的周期性
植物生长的周期性是指植株或器官生长速率随昼夜或季节变化发生有规律变化的现象主要包括生长大周期、昼夜周期和季节周期等。植物生长大周期是指植物初期生长缓慢,以后逐渐加快,生长达到高峰后,又逐渐减慢,至生长停止。形成与细胞生长过程有关,生长初期以细胞分裂为主,细胞数目虽增加较快,但体积增大不多,表现出生长缓慢;中期以细胞伸长和扩大为主,是器官体积和体重增加最显著的阶段;后期则以分化成熟为主,因而生长又趋缓慢,最后停止生长。植物生长大周期中生长进程的变化呈S形。昼夜周期是指植物的生长速率随昼夜温度变化而发生有规律变化的现象。植物生长速率与昼夜温度变化有关。白天气温高,植物蒸腾作用强,呼吸消耗大,同时紫外线对植物生长也有抑制作用,因而白天比夜间长得慢。但在早春时由于夜间气温低,植物在夜间生长反而比白天慢。季节周期是指植物在一年中的生长随季节的变化而呈现一定的周期性规律。温带树木的生长,随着季节的更替表现出明显的季节性,即春季和初夏雨水充足,生长快,盛夏时节蒸腾作用强,生长慢甚至停止生长,秋季生长速度又有所加快,冬季停止生长或进入休眠期。木本植物中早材和晚材的变化,就是由于形成层细胞季节周期性活动的结果。 相似文献
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毛发生长周期 总被引：1，自引：0，他引：1
宋瑞超 《畜牧兽医科技信息》2012,(1):21-22
大多数动物的毛发生长呈现一种循环性变化,生长大致可分为三个时期,即毛发生长初期、毛发生长中期和毛发生长末期。本文对毛囊形成、毛发周期学说、毛发生长不同时期的特征进行了综述。 相似文献
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为了给红灯笼樱桃适时施肥和果实适期采收提供理论依据，并为制定科学的栽培技术和管理措施提供参考。定期调查4～5年生红灯笼樱桃新梢和果实生长发育动态及其相关性。结果表明：（1）新梢生长从3月上旬开始，一直生长到8月下旬停长，生长期达140天，在生长发育过程中出现一～四次生长高峰期，其中伸长生长一～四次，生长量四次，净生长量一次；叶片生长二～三次，生长量三次，净生长量二次；加粗生长四次，生长量和净生长量都四次。（2）果实生长从4月上旬为花谢幼果期开始,一直长到6月中旬停长期,生长期长达56～63天，果实纵横径在整个生长过程中出现次二～三次生长高峰期，其生长量三次；净增长量二～三次生长高峰：其中果实纵径二次；果实缝合线横径三次；果实非缝合线横径出现二次。（3）果实生长与新梢生长的相关性：果实生长量曲线和新梢生长量曲线都是逐步升高的单曲线，其新梢伸长生长和果实生长是一致的，呈双S曲线；果实净生长量有明显的二～三次生长高峰期，其生长曲线是S曲线或双S曲线，而新梢伸长生长的净生长量有一～四次生长高峰期，其中伸长生长是一次高峰，生长曲线呈凸曲线，加粗生长的净生长量有四次生长高峰期，其生长曲线呈三S曲线。（4）建议樱桃进行栽培管理时要求在头年加强水肥管理的同时，在4月下旬作为最佳施肥时期施肥，同时在果梢生长旺期加强根外追肥，来缓解养分的竞争。 相似文献
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目的:探讨腐植酸钠对AA肉鸡肌肉生长规律的影响。方法:240只1日龄AA肉鸡,公母各半,随机等分4组,每组2个重复,每个重复30只。Ⅰ组为空白对照组,饲喂基础日粮;Ⅱ、Ⅲ、Ⅳ组为处理组,饲喂基础日粮并分别添加1.0g/kg、1.5 g/kg、2.5g/kg的腐植酸钠。在14、28、42日龄每个重复随机抽取4只,称取称取胸肌重、腿肌重,分析相对生长、绝对生长、累积生长。结果:(1)胸肌各日龄段相对生长、绝对生长各组间差异均不显著(P>0.05)。虽未达到显著水平,但14~28日龄时试验组相对生长、绝对生长均大于对照组,而28~42日龄时试验组相对生长、绝对生长均小于对照组。(2)腿肌各日龄段相对生长、绝对生长各组间差异均不显著(P>0.05),同时,各组间相对生长、绝对生长也无明显的变化趋势可循。结论:腐植酸钠对AA肉鸡胸肌、腿肌的相对生长和绝对生长没有明显的改变。 相似文献
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本实验研究了红曲米及山楂作为饲料添加剂对生长育肥猪生长性能及消化率的影响。结果表明,红曲米及山楂对生长育肥猪促生长效果与抗生素相当。 相似文献
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促生长激素轴与铜促生长的关系 总被引：7，自引：0，他引：7
日粮中添加适量的铜可显著促进动物的生长,但其确切作用机理不明确,动物的生长受生长激素（ＧＨ）和胰岛素样生长因子（ＩＧＦ）轴的调控,ＧＨ和ＩＧＦ水平因铜的添加而显著升高,并与铜促生长发生密切相关,其机理可能是铜能调控促生长调节肽的合成和释放。 相似文献
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Tomoaki ONODA Ryuta YAMAMOTO Kyohei SAWAMURA Harutaka MURASE Yasuo NAMBO Yoshinobu INOUE Akira MATSUI Takeshi MIYAKE Nobuhiro HIRAI 《Journal of Equine Science》2013,24(4):63-69
Percentile growth curves are often used as a clinical indicator to evaluate variations of
children’s growth status. In this study, we propose empirical percentile growth curves
using Z-scores adapted for Japanese Thoroughbred horses, with considerations of the
seasonal compensatory growth that is a typical characteristic of seasonal breeding
animals. We previously developed new growth curve equations for Japanese Thoroughbreds
adjusting for compensatory growth. Individual horses and residual effects were included as
random effects in the growth curve equation model and their variance components were
estimated. Based on the Z-scores of the estimated variance components, empirical
percentile growth curves were constructed. A total of 5,594 and 5,680 body weight and age
measurements of male and female Thoroughbreds, respectively, and 3,770 withers height and
age measurements were used in the analyses. The developed empirical percentile growth
curves using Z-scores are computationally feasible and useful for monitoring individual
growth parameters of body weight and withers height of young Thoroughbred horses,
especially during compensatory growth periods. 相似文献
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Tomoaki ONODA Ryuta YAMAMOTO Kyohei SAWAMURA Yoshinobu INOUE Akira MATSUI Takeshi MIYAKE Nobuhiro HIRAI 《Journal of Equine Science》2011,22(2):37-42
Thoroughbred horses are seasonal mating animals, raised in northern regions or countries.
Foals born yearly in spring generally show a typical seasonal compensatory growth pattern,
in which their growth rate declines in the first winter and increases in the next spring.
In this study, a new empirical adjustment approach is proposed to adjust for this
compensatory growth when growth curve equations are estimated, by using 1,633 male body
weights of Thoroughbreds as an illustrating example. Based on general Richards growth
curve equation, a new growth curve equation was developed and fit to the weight-age data.
The new growth curve equation had a sigmoid sub-function that can adjust the compensatory
growth, combined with the Richards biological parameter responsible for the maturity of
animals. The unknown parameters included in the equations were estimated by SAS NLMIXED
procedure. The goodness of fit was examined by using Akaike’s Information Criterion (AIC).
The AIC values decreased from 13,053 (general Richards equation) to 12,794 (the newly
developed equation), indicating the better fit of the new equation to the weight-age data.
The shape of the growth curve was improved during the period of compensatory growth. The
proposed method is one of the useful approaches for adjusting seasonal compensatory growth
in growth curve estimations for Thoroughbreds, and for their management during the
compensatory period. Based on this approach, the optimal growth curve equations can be
estimated also for female body weight of Thoroughbreds or other growth traits affected by
seasonal compensatory growth. 相似文献
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Evidence is discussed which indicates that nutrient partitioning between muscle and adipose tissue can be altered by growth hormone administration in meat animals. In the limited number of studies conducted with meat animals, growth rate, feed efficiency and carcass composition were improved by growth hormone administration. When insulin was administered to normally growing swine no improvement in growth performance was observed. The mechanisms by which growth hormone affects growth performance are not clear but considerable data from rodent studies exist to indicate that many of the growth promoting effects of this hormone are due to somatomedins. However, few data are available for meat animals to indicate whether the growth promoting effects of growth hormone are mediated by somatomedins. Knowledge about the mechanisms that regulate growth hormone synthesis, secretion and biological action is accumulating. It is apparent that growth hormone administration induces an insulin-resistant state in rodents and meat animals. It is not clear whether chronic growth hormone administration in meat animals induces a growth hormone resistant state. Based on the available information, manipulation of systemic hormone concentrations and(or) tissue sensitivity to hormones involved in growth and differentiation may result in means to manipulate fetal and postnatal growth and development. 相似文献
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生长率假说（GRH）是研究生物生长率与化学计量特征之间关系的理论。为了验证生长率假说，以北方草原重要建群种羊草（Leymus chinensis）为材料，将取自内蒙古和吉林省4个地点的羊草在相同的光照、水肥条件下盆栽土培，用称重法测定了羊草的生长率，用PCR的方法分析了羊草核糖体DNA基因间隔区（IGS）长度，研究了羊草生长率与羊草磷含量、氮磷比、IGS长度及取样地土壤中氮、磷含量之间的关系。结果表明，羊草生长率与羊草全磷含量存在正相关关系，与羊草氮磷比存在负相关关系，生长率较高的羊草具有较长的IGS，符合生长率假说的预测。不同来源的羊草种植在相同环境下，来自氮、磷含量较高土壤的羊草具有较高的生长率，这可能是羊草对特定地域生境条件长期适应的结果。高的生长率和长的IGS可能是植物对较高氮、磷含量环境的适应。 相似文献
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为揭示马岗鹅的生长发育规律,挖掘马岗鹅的生长潜力,本研究通过测定马岗鹅0~12周龄的体重和体尺性状,并用Logistics、Von Bertalanffy和Gompertz 3种模型进行生长曲线拟合。结果表明:马岗鹅体重生长曲线最佳模型为Gompertz模型(R2=0.999),拐点周龄是4.31周龄,拐点体重是1459.01g,2~8周龄的周增重都在320 g以上,相对生长率都在16%以上,8周龄前为马岗鹅体重迅速增长时期。胸深、龙骨长、颈长的最佳拟合模型为Gompertz,拐点周龄分别为0.65、3.71、2.28周龄;体斜长、半潜水长的最佳拟合模型为Von Bertalanffy,拐点周龄分别为0.53、0.47周龄;胸宽、骨盆宽、胫长、胫围的最佳拟合模型为Logistic,拐点周龄分别为3.81、1.39、0.91、0.51周龄;7周龄前为马岗鹅体尺性状迅速增长时期。本研究结果可为马岗鹅的生产和饲养管理提供理论指导。 相似文献
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夏秋季刈割能促进白三叶及杂草的高度生长,杂草的生长速度大于白三叶。刈割间隔时间是影响白三叶及杂草高度生长的主效因子,间隔时间越短,白三叶及杂草的高度生长越慢。高留茬频密刈割(15 d-10 cm)能使白三叶和杂草均保持较高的生长速率,低留茬每月刈割1次(30 d-5 cm)能使白三叶和杂草均保持较低的生长速率,低留茬频密刈割(15 d-5 cm)是控制杂草的最佳手段,但同时也抑制了白三叶的生长。既能较好地抑制杂草生长又不影响白三叶生长的最佳处理组合为30 d-5 cm,白三叶生长速度0.28 cm/d,杂草0.34 cm/d。 相似文献