问题 问答题 简答题

简述嫁接成活的原理及其影响嫁接成活的因素。

答案

参考答案:

原理:嫁接能否成活,主要决定于砧木和接穗二者的削面,特别是形成层间能否互相密接产生愈伤组织,并进一步分化产生新的输导组织而相互连接。嫁接能够成活,主要是依靠砧木和接穗之间的亲和力以及结合部位伤口周围的细胞生长、分裂和形成层的再生能力。

影响嫁接成活的内在因素:砧木和接穗的亲和力、砧木和接穗的年龄,嫁接的时期,嫁接的方法以及嫁接人的技术的好坏,嫁接工具等。

外部因素:温度,湿度,光照和水分,大风。

单项选择题 A1/A2型题
单项选择题

Beyond question, Clinton was supposed to close up, stay out of sight, and avoid second- guessing his wife’s boss. After his ego blustered into oncoming traffic during Hillary’s heated primary race (1) Obama, the nation suffered from yet another turn of Clinton fatigue.

(2) this week Bill Clinton showed an instinct for robust, inclusive leadership that the (3) White House occupant could make good use of right for the time being. With President Obama struggling to (4) the political damage from the Gulf oil spill, Clinton not only can’t help himself—he’s worth being listened.

The conventional-wisdom (5) on President Obama’s early reaction to the spill was (6) he didn’t emote enough. He didn’t feel the (7) of all those people in the crisis whose livelihood would be destroyed, whose clean waters and wildlife would be (8) in black gunk.

Clinton considers this is an unfair (9) but offers a different—and more pointed— lesson to his young successor. "I think we ought to (10) in the same boat for a while... Let’s just (11) the problem, and then we can hold everybody responsible and emote or not emote, " Clinton conversed (12) CNN Anchor Wolf Blitzer.

Obama’s first (13) after the oil spill was to "feel the blame" rather than "feel the pain, " which are pretty sarcastic words as it were. No one intends to let British Petroleum (BP) management (14) the hook—for dangerously cutting corners, and for a (15) safety record. However, the President’s (16) focus on scolding BP consumed (17) White House energy while the oil gushed.

Great leaders don’t rush to criticise; Instead they instinctively (18) solutions. Rudy Giuliani, who didn’t stop to blame (19) intelligence for letting it happen, stood out from New York mayor with a girlfriend problem to 9/11 hero when he took control of a crisis and instilled confidence that a ravaged city could (20) beyond a terrorist attack.

16()

A.important

B.special

C.initial

D.sharp