马鈴薯脱毒种薯早收试验

1984～1985年,作者在北京延庆县田间观察马铃薯脱毒种薯早收对减少种薯感染病毒的效果。在桃蚜迁飞高峰后10～15天割秧的(以下简称割秧)病毒感染率很低:1984年0.08～0.25%;1985年1.17～1.50%。不割秧的病毒感染率很高:1984年0.83%;1985年3.30%。翌年挖取芽眼经病毒提取作PVX、PVY和TMA血清鉴定,割秧者呈阴性反应,不割秧者呈阳性。翌年将所得种薯栽种田间目测病毒症状,割秧者未见症状,不割秧者病毒株率5.5%。割秧每亩8000穴的亩产10克以上的种薯块数达32240～37600块,而不割秧正常密度的亩产10克以上种薯块数只16400～26800块。因此,早割秧密植不仅可以减少病毒感染,而且利于加大种薯繁殖系数。

EXPERIMENT ON EARLY HARVESTING VIRUS-FREE SEED POTATOES

The effect of early harvesting virus-free seed potatoes on reducing the rate of virus infection was investigated in the field of Yanqing,Beijing from 1984 to 1985.If potato haulms were cut off at the day after 10-15 days of peach aphis' immigration peak,the rate of virus infection was low,which was 0.08-0.25% in 1984 and 1.17-1.50% in 1985.If the potato haulms were not cut off,the rate of virus infection was high,which was 0.83% in 1984and 3.30% in 1985.Next year,the virus was extracted from digged potato eyes,and the serological tests to PVX,PVY and TMV were carried out.The result indicated that it was negative reaction if the potato haulms were cut off early last year,and positive reaction if the potato haulms were not cut off.The potatoes harvèsted were grown in the field in order to observe the virus symptoms next year.The result indicated that plants originated from the potatoes whose haulms were cut off last year had no virus symptoms;while the plants originated from the potatoes whose haulms were not cut off hadvirus symptoms,whose virus infection rate was 5.5%.The number of tuber which weighed more than 10 grams were 32240-37600 if the density of plants was 8000 hills per mu and the potato haulms were cut off early;while the number of tuber which weighed more than 10 grams were 16400-26800 if the density of plants was normal and the potato haulms were not cut off.Therefore cutting potato haulms off early in combination with close planting not only decreased the rate of virus infection but also increased the yield of seed potatoes.