Quantity Dynamic Of Oat Aphid Population And Its Resistance To Oat

Oat is not only an important crop used for forage and grain, but also a nutritional crop of health protection. As one of the most important pests which feed on oat, the occurrence and damage generated by aphid have aggravated as the change of climate in recent years. The quantity dynamic of aphid was investigated based on the current studies on the damage of aphid from both in and abroad, and aphid resistance capabilities of different oat varieties were identified in and out of the lab, respectively.1. Study on quantity dynamic of aphid population in oatThe investigation results showed that the aphid species which feed on oat were Metopolophium dirhodum, Rhopalosiphum. Padi and Sitobion avenae. The occurrence period and feeding position on oat were different. Rhopalosiphum. Padi, Linnaeus's occurrence period was prior to other aphids and it mostly feeding on the lower sheath and stalk of oat; the number of Metopolophium dirhodum increased gradually with the warming of temperature, it mostly feeding on the obverse and reverse sides of oat leaf. The number of Sitobion avenae increased gradually after oat earring, and reached its maximum during oat filling stage. The present paper deals with the effects of temperature on the development, survival and reproduction of Metopolophium dirhodu. at six different temperatures (12℃,15℃,18℃, 21℃,24℃and 27℃) and at the relative humidity of 65% (65% RH). The life tables were constructed and life parameters were compared of the 6 treatments. At 18℃and 80% RH, the intrinsic rate of natural increase was the highest (r_m =0. 0.306) and the finite rate of increase (λ) was 1.358/d. The mean generation time (T) was 11.013 d and the net reproductive rate (R0) was 29.090.2. Study on aphid-resistance capability of different oat varietiesThe resistance capability of different aphid varieties to oat was appraised with the method of aphid injury index in field. The results showed that Caoba No3 was immunity variety; Qingyongjiu 440 and Qingyongjiu 409 were high resistant varieties; Qingyongjiu 118 was medium resistant variety; Qingyongjiu42 and two other varieties were resistant varieties; N235 was susceptive variety; Qingyongjiu473 and eight other varieties were high susceptive varieties.3. Study on aphid-resistance substances in the seedlings of five oatsQinyongjiu118, Qinghai tianyanmai, Qingyin No2, Danmai444 and vaccinate aphid were inoculated with aphids when the plants came to three leaves, and 30 aphids for each plant. Chlorophyll, soluble sugar, soluble proteins, and total phenols contents were tested before inoculation and on the 2^nd, 4^th and 6^th day of inoculation, un-inoculated plants at the same period were used as control group. The results indicated that as the increase of time, chlorophyll content decreased obviously in all varieties, and the total phenol contents which were believed as aphid-resistance substances increased, the same with soluble sugar and soluble protein. It is showed that the aphid-resistance capability of oat is closely related to the contents of soluble sugar, soluble protein and total phenol contents in plant.