Method for identifying pear germplasm pear gall midge resistance
Technical Field
The invention belongs to the field of fruit tree research, and relates to a pear germplasm anti-gall midge identification method, which can effectively solve the problem of rapid identification of pear variety anti-gall midge in pear scientific research, breeding and production. The method is suitable for scientific research units, companies and individuals engaged in pear scientific research, breeding and production.
Background
The pear belongs to the Rosaceae (Rosaceae) Maloideae (Maloideae) pear (Pyrus) plant, is a tree with tree leaves and fallen leaves, is one of three cultivated fruit trees in China, and plays a very important role in the world. According to statistics of agricultural rural departments in the people's republic of China, the pear planting area of 2016 years in China is 1113 kilohectares, the yield is 1870.44 ten thousand tons, and the pear is the first place in the world. Pear production is always an important post industry for increasing income and leading to wealth of farmers in China and is also one of main agricultural products for earning foreign exchange in exports of China. Along with the continuous expansion of the planting area of pears, various pest and disease damages of the pears are getting more and more serious day by day, and the pest and disease damages of the pears are getting more and more rampant day by day in recent years, and become the main pests of the pears.
Pear gall midge mainly takes larvae as flower buds, young tips and young leaves of a damaged pear tree, nail holes for adult pear gall midge to lay eggs are formed outside damaged flower buds, eggs are hatched into larvae in the flower buds, the larvae damage stamens and pistils, and after the flower buds are damaged, the interior of the flower buds become black, so that normal pollination and fruit setting cannot be realized; the pear gall midge harms the young leaves of the pears after blossom withering, the juice is absorbed at the leaf edge on the front side, the leaves are shriveled and deformed, become tumor-shaped and crisp, and are longitudinally and inwards rolled into a tight tube shape, and the pear gall midge larvae can be stripped in the damaged rolled leaves. The damaged leaves are curled into a cylinder shape, the leaf surfaces are uneven, the leaves are browned, dried and fallen off, bald branches are left, and the growth, development and yield of the tree body are seriously influenced. The spring tip, summer tip and autumn tip can be damaged. After buds, young leaves and young tips are damaged by pear gall midge, a large amount of flowers, fruits and leaves are easy to fall in the early stage, and the yield and the quality of pear trees are seriously influenced. After a part of the pear gardens are damaged, healthy branches and tips cannot be taken out all the year round, and the high yield performance of the pear trees is seriously weakened. Because the insect is damaged in the leaf curl, common insecticides are difficult to touch and kill the insect, the control difficulty is very high, the insect is one of the problems to be solved urgently in managing the pear orchard, and the damage of the pear gall midge seriously threatens the development of the pear industry. The existing method for preventing and controlling pear gall midge is to use chemical agents such as 22.4 percent of spirotetramat suspending agent, 10 percent of imidacloprid, 40 percent of chlorpyrifos, 1.8 percent of abamectin and the like. If the chemical agents are used for a long time, the problems of drug resistance of pests to the chemical agents, environmental pollution, harm to human health and the like are inevitably caused if the chemical agents are not used properly. In order to overcome the defects of drug resistance of chemical agents and reduction of chemical pesticide pollution, a reasonable and effective comprehensive control measure of pear gall midge is imperative. Screening of Chinese pear varieties with strong pear gall midge resistance is the most effective method for preventing and treating pear gall midge, but how to quickly and accurately identify the characteristic that pear varieties have pear gall midge resistance in the large-area popularization process is a major problem which needs to be solved in the front of scientific research and production personnel.
For years, based on the national fruit tree germplasm resource garden, a large number of scientific researches and tests are developed around the identification and evaluation of pear germplasm for resisting pear gall midges, and a set of pear germplasm anti-pear gall midge identification method is summarized and invented. The method is characterized in that when field pear gall midge larvae damage pear trees in the peak period, the new tip damage rate and the leaf damage rate of pear germplasm are investigated, the comprehensive damage rate of pear germplasm pear gall midge is calculated according to the new tip damage rate and the leaf damage rate of the pear germplasm, the pear germplasm pear gall midge-resistant identification standard is established, and pear variety pear gall midge-resistant identification evaluation is carried out on pear varieties.
Disclosure of Invention
The invention aims to provide a pear germplasm pear gall midge resistance identification method, which can be used for quickly and accurately identifying and evaluating pear gall midge resistance of pear varieties.
In order to achieve the purpose, the invention adopts the following technical measures:
a method for identifying pear germplasm pear gall midge resistance comprises the following steps:
a: determining the investigation time;
b: a step of investigation;
c: calculating the comprehensive hazard rate of the pear germplasm;
d: identifying and grading pear germplasm for resisting pear gall midges;
the method comprises the following steps:
when the field environment temperature reaches 30 ℃, carrying out investigation on the branch damage rate and the leaf damage rate of the pear varieties 2 weeks after the emergence peak period of the second generation pear gall midge imagoes, namely in the middle 6 th of the month;
the step B comprises (1) investigation of new damage rate of pear tree
Randomly investigating 6 trees in each germplasm, investigating five directions of east, west, south, north and middle, and randomly investigating 10 annual new shoots in each direction; the damage of 1 or more leaves on the new tip of the pear tree by pear gall midge is defined as the new tip damage;
calculating the new tip damage rate of each plant according to the number of new tip damage branches in each direction of each pear tree;
SXW%=(XW-E+XW-W+XW-S+XW-N+XW-C)/50×100%
in the formula: SXW percent-single plant new tip hazard rate
XW-E-the number of branches damaged by new oriental pear tree
XW-W-number of branches newly damaged by western pear trees
XW-S-number of newly damaged branches in south of pear tree
XW-N-number of branches newly damaging northern pear tree
XW-C-the number of branches newly damaged by central trunk of pear tree
6 pear trees were investigated repeatedly. Calculating an average value;
(2) investigation of harm rate of pear leaves
Randomly investigating 6 trees in each germplasm, investigating five directions of east, west, south, north and middle of each tree, randomly investigating 5 annual new tips in each direction, defining leaves on the new tips as harmful leaves by pear gall midge harmful leaf rolls, and statistically investigating the number of the harmful leaves on each new tip and the total number of the leaves on each new tip;
calculating the damage rate of the single leaf according to the number of the damage of the leaf in each direction of each pear tree and the total number of the leaves of each new tip;
SYW%=(YW-E+YW-W+YW-S+YW-N+YW-C)/(YWT-E+YWT-W+YWT-S+YWT-N+YWT-C)×100%;
in the formula: SYW-individual leaf hazard rate
YW-E-pear tree eastern survey of number of leaves endangered by new tip
YW-W-pear tree western investigation of new-tip damage leaf number
YW-S-pear tree southern survey of number of leaves damaged by new tip
YW-N-pear tree northern investigation on number of leaves newly damaged by new tip
YW-C-pear tree central trunk survey of number of new damaged leaves
YWT-E- -total number of leaves of oriental surveyed branch of pear tree
YWT-W-total number of leaves of western boughs
YWT-S- -total number of leaves of southern surveyed branch of pear tree
YWT-N-total leaf number of northern survey branch of pear tree
YWT-C-investigation of the total number of branch leaves in the central trunk of the pear tree;
6 pear trees are investigated repeatedly; calculating an average value;
the step C is as follows:
combining survey data of the new tip hazard rate and the leaf hazard rate, and calculating the comprehensive hazard rate according to the weight of the new tip hazard rate and the leaf hazard rate in the pear gall midge resistance identification;
ZW%=XW%×85%+YW%×15%
in the formula: ZW% - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
XW% - - - - - - - -new tip hazard ratio
YW% - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -;
the step D is as follows:
determining the resistance of the pear germplasm to the pear gall midge according to the comprehensive hazard rate of the pear germplasm and the following standards;
the resistance of the pear species to the pear gall midge is divided into 5 grades according to the comprehensive hazard rate;
1 Extremely Strong (ES) (comprehensive hazard rate less than 20%)
3 strong (S) (20 percent or more and less than 40 percent of comprehensive hazard rate)
5 medium MS (40% or more and less than 60% of comprehensive hazard rate)
7 Weak (W) (60% more than or equal to the comprehensive hazard rate less than 90%)
9 Extremely Weak (EW) (the comprehensive hazard rate is more than or equal to 90 percent).
The rapid identification of pear variety pear gall midge resistance in the pear scientific research, breeding and production can be effectively solved through the treatment of the invention, and the pear variety pear gall midge resistance identification evaluation is carried out.
Drawings
FIG. 1 shows the comprehensive hazard rates of pear gall midge of different pear germplasm resources;
FIG. 2 shows the identification results of different pear gall midge resistant pear varieties.
Detailed Description
The invention is further illustrated by the following specific examples:
a method for identifying pear germplasm pear gall midge resistance comprises the following steps:
1. investigation time
When the field environment temperature reaches 30 ℃, the pear variety branch damage rate and leaf damage rate are investigated 2 weeks, namely 6 months and 15 days, after the emergence peak period of the second generation pear gall midge imagoes.
2. Investigation method
(1) Investigation of pear tree new-tip hazard rate
And randomly investigating 6 trees in each germplasm, wherein each tree is investigated in the east, west, south, north and middle directions, and each direction randomly investigates 10 annual new shoots. The damage of pear gall midge to 1 or more leaves on the new tip of the pear tree is defined as the new tip damage.
And calculating the new tip damage rate of each plant according to the number of the new tip damage branches in each direction of each pear tree.
SXW%=(XW-E+XW-W+XW-S+XW-N+XW-C)/50×100%
In the formula: SXW percent-single plant new tip hazard rate
XW-E-the number of branches damaged by new oriental pear tree
XW-W-number of branches newly damaged by western pear trees
XW-S-number of newly damaged branches in south of pear tree
XW-N-number of branches newly damaging northern pear tree
XW-C-the number of branches newly damaged by central trunk of pear tree
6 pear trees were investigated repeatedly. The average value is calculated.
(2) Investigation of harm rate of pear leaves
And randomly investigating 6 trees in each germplasm, investigating five directions of east, west, south, north and middle of each tree, randomly investigating 5 annual new tips in each direction, defining leaves on the new tips as harmful leaves by pear gall midge harmful leaf rolls, and statistically investigating the number of the harmful leaves on each new tip and the total number of the leaves on each new tip.
And calculating the damage rate of the single leaf according to the number of the damage of the leaves in each direction of each pear tree and the total number of the leaves of each new tip.
SYW%=(YW-E+YW-W+YW-S+YW-N+YW-C)/(YWT-E+YWT-W+YWT-S+YWT-N+YWT-C)×100%
In the formula: SYW-individual leaf hazard rate
YW-E-pear tree eastern survey of number of leaves endangered by new tip
YW-W-pear tree western investigation of new-tip damage leaf number
YW-S-pear tree southern survey of number of leaves damaged by new tip
YW-N-pear tree northern investigation on number of leaves newly damaged by new tip
YW-C-pear tree central trunk survey of number of new damaged leaves
YWT-E- -total number of leaves of oriental surveyed branch of pear tree
YWT-W-total number of leaves of western boughs
YWT-S- -total number of leaves of southern surveyed branch of pear tree
YWT-N-total leaf number of northern survey branch of pear tree
YWT-C-total leaf number of survey branch of central trunk of pear tree
6 pear trees are investigated repeatedly, and the average value is calculated.
3. Calculation of comprehensive hazard rate of pear germplasm
And (4) combining survey data of the new tip hazard rate and the leaf hazard rate, and calculating the comprehensive hazard rate according to the weights of the new tip hazard rate and the leaf hazard rate in the pear gall midge resistance identification.
ZW%=XW%×85%+YW%×15%
In the formula: ZW% - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
XW% - - - - - - - -new tip hazard ratio
YW% - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
4. Identification and classification standard for pear germplasm pear gall midge resistance
The resistance of the pear germplasm to the pear gall midge is determined according to the comprehensive hazard rate of the pear germplasm and the following standards.
The resistance of pear breeds to pear gall midges is classified into 5 grades according to the comprehensive hazard rate.
1 Extremely Strong (ES) (comprehensive hazard rate less than 20%)
3 strong (S) (20 percent or more and less than 40 percent of comprehensive hazard rate)
5 medium MS (40% or more and less than 60% of comprehensive hazard rate)
7 Weak (W) (60% more than or equal to the comprehensive hazard rate less than 90%)
9 Extremely Weak (EW) (the comprehensive hazard rate is more than or equal to 90 percent).
Example of the experiment 1: in 2018, 582 parts of pear germplasm resources in the fruit tree germplasm Wuchang sand pear garden of China are subjected to the method
And (4) identifying and evaluating pear gall midge resistance of the Chinese pear.
As can be seen from the figures 1 and 2, through the identification and evaluation of the pear gall resistance of 582 parts of pear germplasm resources in the national fruit tree germplasm Wuchang sand pear garden by using the method, 124 parts of pear gall midge resistant variety, 148 parts of strong resistant variety, 151 parts of medium resistant variety, 157 parts of weak resistant variety and 2 parts of weak resistant variety are screened out. The identification result lays a test foundation and a theoretical basis for breeding the pear gall midge-resistant pear variety.