THE EFFECT OF PHOTOPERIOD AND TEMPERATURE ON THE RELATIONSHIP BETWEEN THE ROOT AND SHOOT SYSTEMS OF LOLIUM PERENNE

In controlled environment cabinets, root growth relative to shoot growth varied directly with the temperature within the range 50·–80·F. Increasing the photoperiod from 6 to 12 hours increased the root growth relative to shoot growth; additional hours of light had no further influence on this ratio. These results are discussed in relation to the maintenance of a balance between photosynthesis and the absorption of water and minerals.     

STUDIES ON THE HEIGHT/WEIGHT RELATIONSHIP IN DESERT RANGE GRASSES OF INDIA

Studies on height/weight relationship of the key grass species of Western Rajasthan ranges, India, were undertaken so as to form concepts which will guide the assessnient of the extent of their utilization by the livestock. Regression studies of the data obtained indicated that the relationship between the percentage of height clipped and the percentage of weight removed is quadratic. A graph has been drawn for each of the 5 species to relate the percentage of height removed with the percentage of weight utilized. The studies have shown that the weight distribution in respect of height is different in different species.     

野生大豆结瘤固氮与叶片和籽粒含氮量的关系

17份野生大豆的盆栽试验结果指出,野生大豆在结瘤固氮方面存在着明显的基因型差异。花期根瘤数、根瘤鲜重和固氮酶活性与单株叶片含氮量呈显著或极显著的正相关,固氮酶活性与单株籽粒氮产量呈正相关,分枝期、花期、结荚鼓粒期的相关系数分别为0.401,0.478和0.512。     

SPRING AND SUMMER ROOT GROWTH OF SOME TEMPERATE–REGION GRASSES AND SUMMER ROOT GROWTH OF TROPICAL GRASSES

The root growth of 3 temperate–region grasses (perennial ryegrass, Italian ryegrass, and cocksfoot) and of 3 tropical grasses (Dallis grass, Bahia grass, and Rhodes grass) was investigated in large glass–sided root–boxes. The trend of root numbers and the rate of elongation of roots were ascertained to discover how the Japanese climate affected the root growth of these species.
All the temperate–region grasses produced new roots vigorously during spring, but root growth ceased in August, whereas the roots of tropical grasses grew rapidly in this month. The alternate use of these two types of grasses during the growing season may therefore be worthwhile in Japan     

大豆植株光合性能与干物质及荚粒形成关系的研究

大豆生育期间,群体中的单株干物质日增量、单株光合速率及单株光合面积均呈单峰曲线变化。其中,日增量在开花期以前和鼓粒期以后受光合面积的支配,而在开花期至鼓粒期则主要受光合速率的制约。 群体中的单株各节位间,叶片平均光合速率、平均光合面积、总光合势和总光合量与荚数、粒数及总粒重的高低分布趋势基本一致、均以中上部节位最大,基部和顶部节位最小。各指标间,以总光势和总光合量与籽粒数及总粒重的线性正相关较强,达显著水平。 结果还表明,盆栽植株各节位叶片的光合性能和荚粒形成量,均优于群体中的单株各对应节位叶。     

连作大豆根冠比增大原因的研究

通过对轮、连作大豆干物质积累量的定期测定，发现连作大豆根、冠干物质积累量均低于轮作，根冠比（Ｒ／Ｓ，干重比）增大。这主要是由于连作大豆根系病虫害加重，磷、钾等元素亏缺，水分胁迫较重，内源生长素（ＩＡＡ）、赤霉素（ＧＡ３）、玉米素核苷（ＺＲｓ）、脱落酸（ＡＢＡ）的含量及比例变化导致冠部降低幅度大于根系，最终使根冠比增大。     

大豆根系生长和活性特点的研究

本试验利用框架剖面法测定了大豆根系的生长动态和根系活性变化。结果表明：大豆根系生长过程呈Ｓ型曲线变化，形成慢生长（Ｖｅ－Ｖ３），快速生长（Ｖ３－Ｒ５）和衰老（Ｒ５），三个阶段，高峰值出现在Ｒ４－Ｒ５阶段。根系活性变化与根系生长特点相似，Ｒ１时期之前根系活性逐渐增强，Ｒ２时期之后根系活性下降。根系活性变化比根系生长提前。     

STUDIES ON THE ROOT DEVELOPMENT OF HERBAGE PLANTS

Various methods of root sampling are reviewed and discussed in relation to the type of information required. The root sampling techniques at the Grassland Research Institute are described and examples of sampling errors are given. Details of a root washing machine are given.     

STUDIES ON THE ROOT DEVELOPMENT OF HERBAGE PLANTS

The influence of defoliation on the root, stubble and herbage weights of perennial ryegrass during establishment was studied on spaced plants in the greenhouse and field.
In the greenhouse trial the rate of root elongation was reduced by a single defoliation. In both the field and greenhouse, cutting reduced the number of roots and tillers per plant but increased the number of roots per tiller. A few weeks after defoliating plants in the field there was a lower root weight on the cut plants than on the uncut. Eventually the influence of a single cut disappeared, but if the cutting was in the laie summer or autumn the plants commenced the winter with a smaller amount of root and stubble, and this appeared to have a deleterious effect on the earliest spring growth.
Herbage growth in March and April was positively correlated with both root and stubble weights in the previous November.
As the number of cuts during the establishment period (March-November) was increased from 0–4 the root and stubble weight per plant progressively decreased.
The root and stubble weights decreased during the winter.     

STUDIES ON THE ROOT DEVELOPMENT OF HERBAGE PLANTS

Herbage, stubble and root weights were recorded for thirteen months on various leys subjected to two treatments differing in frequency of cutting.
The root-weight per unit area of a ryegrass/white-clover ley was not affected by the frequency of cutting, but the less frequently cut plots had fewer tillers per unit area; the root- and stubble-weight per tiller was, therefore, higher on the less frequently cut plots, On a cocksfoot ley the root-weight was not affected by the cutting treatment, but in late summer and early autumn the stubble-weight was considerably higher on the less frequently cut plots.
When cocksfoot was grown in rows 2 feet apart, the more frequent cutting decreased both the root- and stubble-weight.
On grass leys root-weights were heaviest in the summer and thereafter decreased until the following spring.
The root-weight of lucerne decreased from May to July, increased to a maximum in December and then decreased in weight. The changes in root-weight under lucerne leys were mainly due to changes in the weight of the tap-roots.
The vertical distribution of roots was recorded, and, in the case of the cocksfoot in rows, the lateral distribution of roots is also given.     

STUDIES ON THE ROOT DEVELOPMENT OF HERBAGE PLANTS

Two cutting treatments were applied to a cocksfoot sward, and the changes in fructosan and soluble–sugar contents of the roots, stubble and herbage were studied over a complete year.
Both the soluble-sugar and fructosan contents of roots were at a low level throughout the experiment. The total soluble carbohydrate in the roots never exceeded 4%. It is concluded that cocksfoot roots are not important storage regions for soluble carbohydrates.
The total soluble carbohydrate in herbage varied with season and reached a maximum of 10%. It was not affected by cuuing treatment.
In stubble the total stubble-carbohydrate content fluctuated markedly with season and reached a maximum of 18% in October; it was generally higher on the infrequently-cut swards than on those cut frequently. The soluble-sugar content was small and changed little with season or cutting treatment; the fructosan content, however, varied from 2 to 16–6% and accounted for most of the changes in the soluble-carbohydrate content. Stubble is apparently the major storage region for soluble carbohydrates in cocksfoot.
Under sward conditions, the quantity of soluble carbohydrates in the stubble of cocksfoot may have a positive effect on the herhage growth immediately after winter defoliation. However, when swards are actively growing in spring, other factors, such as tiller size and number, may be equally important in determining the amount of herbage recovery growth.     

马铃薯高淀粉生理基础的研究——块茎淀粉含量与糖的代谢

本试验以高淀粉品种晋薯2号、中淀粉品种内薯3号和低淀粉品种紫花白为试验材料,设置了小区试验,在生育期间从还原糖和可溶性糖的代谢与块茎淀粉含量积累变化的相关关系进行了研究,其结果:(1)块茎淀粉含量的积累变化与叶片可溶性糖含量变化呈显著正相关关系.因此,叶片可溶性糖含量可做为马铃薯高淀粉育种早期选择和品质预测的重要生理指标;(2)块茎淀粉含量积累变化与叶片还原糖含量变化呈正相关,故叶片还原糖含量亦可做为马铃薯高淀粉育种早期选择和品质预测的生理指标;(3)块茎淀粉含量积累变化与茎秆、块茎可溶性糖、还原糖含量变化相关性不强,但生育后期与茎秆可溶性糖含量呈显著正相关.     

杂交油菜内源激素的变化特征与杂种优势关系初探

运用酶联免疫法研究了油菜杂种优势与内源激素变化特征的关系，结果表明杂交油菜与常规油莱相比，苗期叶片ＧＡ含量高，ＡＢＡ含量低，营养生长旺盛．杂种优势明显；越冬期叶片ＧＡ含量低，ＡＢＡ含量高，生长缓慢，植株细胞液浓度高，抗寒性强；茎期叶片ＧＡ、ＡＢＡ含量均低，ＧＡ／ＡＢＡ仍然低；薹茎中ＧＡ／ＡＢＡ高，有利于抽薹开花，促进生殖生长。     

大豆籽实产量与其需水量之间关系的研究

大豆不同生育阶段的土壤水份状况与叶细胞浓度和叶水势关系的研究结果表明,上述水份生理指标与土壤湿度呈极显著的相关。不同灌水形式的试验和田间需水量的测定表明,大豆籽实产量71～260kg/亩的需水量为200～367m~3。在此范围内两者近乎直线正相关,当耗水量超过367m~3/亩时大豆籽实产量无明显增加。大豆在幼苗期、分枝期、花荚期、鼓粒期的适宜土壤湿度分别是田间最大持水率的70％、80％、80％、70％。     

大豆根系特征与磷素吸收利用的关系

大豆幼苗经过培养处理形成三种内磷浓度,在两种不同营养液磷水平下进行培养,研究大豆根系特征与磷素吸收利用之间的关系.研究发现,大豆植株体内磷对促进根系的伸长有着非常重要的作用.对于相同的内磷处理,不同外源磷对根长影响较大,外磷浓度越高根长越短,尤其在磷处理后的第3周,S2和S3内磷水平的处理,从P2降低到P1水平时,根长分别增加了5.2%和30.1%.在无外磷的条件下,不同内磷浓度对根表面积的影响从磷处理后的第2周开始均达到了5%的显著水平,而施加外磷的处理,只有在磷处理后的第4和第5周,才达到5%的差异显著水平.在所有的取样时期,植株干生物量与磷效率比值没有达到显著水平,但是,随着磷效率比值的增加,达到0.40以后,植株干生物量随着磷效率比值的增加而增加.植株磷效率比值与含磷量之间达到了1%的显著水平,随着磷效率比值的增加,植株体内含磷量呈指数下降.     

马铃薯高淀粉生理基础的研究——块茎组织结构与淀粉积累的关系

马铃薯块茎以皮层区的淀粉含量最高,环髓次之,内髓最少,但环髓区的淀粉在整个块茎中所占的比重最大,淀粉含量指数也最高;内髓区的淀粉在块茎中占的比重最小,淀粉含量指数也最低.皮层区的淀粉含量高低、皮层的厚度、环髓区的淀粉含量指数与块茎淀粉含量呈显著的正相关、皮层区、环髓区、内髓区的细胞大小、输导系统的筛管和导管面积,随块茎的增大和淀粉的积累而增大,其中除皮层区细胞大小与块茎淀粉含量呈负相关之外,其余各组织的细胞大小与块茎淀粉含量没有明显的相关性.     

大豆生殖生长期根系形态性状与产量关系研究

以稳定的大豆新品系进行连续2年的生殖生长期根系形态性状的比较研究.结果表明,生殖生长期根系形态性状存在较明显的基因型差异,尤其在R5期后,产量较高的海-560的根系生物量、根体积和根长均大于观-009;施肥有效地促进根系生长,降水较多的年份土壤中的根系密度较高,施肥增强这种趋势,尤以0～30 cm内的土层显著;根系性状与产量间存在显著的相关关系,其中根长与产量的关系更为密切.在雨养农业中,选育根系强大的品种,并根据气候变化因地制宜的科学施肥,协调水肥关系,提高水分及养分利用率,对于提高作物产量是十分必要的.