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(一)本试验系在杭州进行的,在这个地区,甘薯地上部干物量的增加可以分为三个时期,第一个时期占全生长期的四分之一,该时地上部干物质积累十分缓慢;第二个时期占全生长期也为四分之一,该时地上部干物质积累急剧增加,达到最高峰;第三个时期占全生长期四分之二,前期地上部干物质积累开始减慢,后期因部分叶片衰老脱落,地上部干物质反而减少。地上部干物量的增加和叶面积系数大小成正比例,即叶面积系数越大,地上部干物量增加也越快,而施肥多少对于地上部干物量的增加和叶面积系数大小有着十分密切的关系,即施肥量多的,其地上部干物量和叶面积系数就大,反之就小。 (二)甘薯块根的产量和地上部干物量的增加有一定的关系,在一定范围内,地上部干物量越大,块根产量也越高;但施肥过多引起徒长的植株,虽地上部干物量也大,而因叶片间相互遮荫,光合条件恶化,同化生产率反而降低,这时地上部干物量的增加不仅不能促使块根膨大,反而还增加块根干物量的消耗,结果降低块根产量。从甘薯的 T/R 率曲线(以地下部块根除地上部)中观察到,地上部养料向下转运越早,块根的形成和膨大也越快,在地上部茎叶生长良好时,后期 T/R 率曲线的下降是越快越好。(三)用放射性 P~(32)试验证明,甘薯地上部不同生长状况与叶片养料向块根运输有密切的关系,植株生长良好产量较高的甘薯,其地上部各器官的养料,从块根开始膨大起,就逐渐向地下部块根转移,后期转移更其加快。同时块根产量越高的,后期地上部各器官输向块根中的养料也就越多;块根产量较低的,后期地上部输向块根中的养料也就减少。甘薯各生育期有其相应的养料分配中心,生育前期植株养料大多输向于茎叶,以后逐渐转向于叶及根,最后大部分养料都集中于根中。因此,在甘薯生育前期,如何通过栽培措施,迅速增大绿色叶面及分枝数,为后期块根膨大打下物质基础;又在后期如何促使地上部养料能及时和迅速地向块根转运,这是提高甘薯产量的一个重要关键。
(A) The experiment was carried out in Hangzhou. In this area, the increase of dry matter in aboveground parts of sweet potato can be divided into three periods, the first one accounting for one fourth of the whole growth period, when dry matter accumulation Very slow; the second period also accounted for one quarter of the full growth period, when the dry matter accumulation aboveground parts increased sharply, reaching its peak; the third period accounted for two quarters of the full growth period, early dry matter aboveground Accumulation began to slow down, due to the late part of the leaves of aging loss, dry matter on the ground but reduced. The increase of above-ground dry matter is proportional to the leaf area coefficient, that is, the larger the leaf area coefficient, the faster the dry matter increase of above-ground part, and the more fertilization is very close to the increase of above-ground dry matter and leaf area coefficient , That is, the amount of fertilizer, the aboveground dry matter and leaf area coefficient is large, otherwise small. (B) the yield of sweet potato tuber and aerial parts of dry matter increased in a certain extent, in a certain range, the greater the amount of dry matter above the ground, the higher the yield of tuberous roots; However, excessive fertilization caused leggy plants, although aboveground dry matter However, the photosynthetic conditions were deteriorated and the assimilation productivity was reduced. At the same time, the increase of dry matter in above-ground part not only failed to promote tuberous root enlargement, but also increased the consumption of dry matter in root tuber and reduced the yield of tuberous root. From sweet potato T / R rate curve (in order to eliminate the aerial part of the underground block) was observed, the transport of shoot nutrients downwards earlier, the formation and expansion of roots faster, when shoots grow well on the ground, the late T The decline of the / R rate curve is as fast as possible. (3) The experiment of radioactive P 32 proved that the growth of sweet potato aboveground was closely related to the transport of leaf nourishment to the root tuber, and the sweet potato with good yield and good plant growth, Dilated, it gradually transferred to the underground roots, the more rapid transfer of late. At the same time, the higher root tuber yield, the more nourishment to the roots of shoots in the shoots at the later stage. The lower root tuber yield would reduce the nourishment in root tuber root. The sweet potato has its corresponding nourishment distribution center during its growth period. Most of the plant nourishment tends to stem and leaf at the early stage of growth, then turns to the leaves and roots gradually. At last, most of the nourishment is concentrated in the roots. Therefore, in the early stage of sweet potato growth, how to quickly increase the number of green foliage and branches through cultivation measures to lay the material foundation for the tuberous root enlargement in the late stage and how to prompt the shoots to transport the shoots to the root in a timely and rapid manner Improve sweet potato production is an important key.