问题 问答题 论述题

制订育种目标时应考虑哪些主要目标性状?

答案

参考答案:

①产量性状:高产是植物育种的基本要求,具有丰产潜力的优良品种是获得高产的物质基础。首先考虑结构性状的合理组合,不同品种产量结构性状不同,在不同自然、生产条件下,各个品种获得高产的群体结构和组成因素可以不同。各产量性状之间相互制约,常带有一定程度的负相关。合理株型是高产品种的生育基础和形态特征。并达到高光效

②品质性状:某些品质特征与产量直接相关;改良作物品质,有利于保证人、畜健康;直接或间接的影响加工工业产品的产量、品质与生产成本

③成熟期:生育期早晚在大部分地区和许多作物都是重要的育种目标性状。

④对病虫害的抗耐性:病虫害的危害对作物的产量和品质都有严重影响,抗病虫品种的选育和应用具有重要作用。

⑤对环境胁迫的抗耐性:环境胁迫因素的抗耐性,是品种选育的重要目标性状,包括温度、水分、土壤矿物质、大气污染及农药胁迫等。

⑥对耕作制度和机械化作业的适应性。

阅读理解
阅读理解。
                                                           Visit the Night Safari
     The Night Safari is a special night zoo and it gives you the only chance of watching wild animals at
night. It has an area of 40 hectares (公顷). You are able to see over1,000 animals here. The Night Safari
took four years to plan and three years to build. It was opened on May 26,1 994.
Opening time
6:00 pm-12:00 midnight every day
                                                                   Tickets
On foot:
Grown-ups: $20
Children (3 to12 years old): $10
Tram (有轨电车) ride:
Grown-ups: $28
Children (3 to12 years old): $14
Don't smoke!
Don't use flash (闪光灯) when taking photos!
1. Why is the Night Safari a special zoo?
A. Because it is a wildlife (野生) park.
B. Because it has an area of 40 hectares.
C. Because it is very large.
D. Because it provides a chance of watching animals at night for people.
2. How many animals are there in the zoo?
A. About 40.
B. Over 40,000
C. More than 1,000
D. More than 2,000.
3. How long did it take people to build the Night Safari?
A. Three years.
B. Four years.
C. Five years.
D. Six years.
4. How much does Mr. Turner have to pay if he visits the zoo by tram with his daughter often years old?
A. $20.
B. $42.
C. $50.
D. $56
5. Which of the following sentences is TRUE?
A. People can't take photos when they visit the Night Safari.
B. The night Safari was built in 1990.
C. The Night Safari took three years to plan.
D. People can visit the Night Safari between 6:00 pm and 12:00 midnight every day.
单项选择题