Effects Of Sowing Date And N Application On Yield And Its Components, N Uptake And Allocation In Oats In Alpine Region

The experiment was conducted at a deer farm in Tianzhu county of Gansu province from April to October in 2006, where the altitude is 2294m above sea level. Four oat cultivars including Baiyan No. 2, Baiyan No.5, Qinhai444 and Ronald were used in this trail to study the effect of sowing date and nitrogen application on yield and its components, N-utilization and allocation in alpine region. The results showed as follows:1.The days to maturity of each cultivar was different under the same treatment, among which, Qinhai-444 had 133 days to maturity, while Baiyan No. 5 was only120 days. With the prolonging of sowing date, days to maturity was postponed. The effect of N-fertilizer was not significant.2.The forage yield was different among 4 cultivars under the same treatment, and the same cultivar responded differently to sowing date and N-application. If aimed at harvesting forage at anthesis, sowing at late of April to early May could achieve higher yield under 100kg/hm2 N-fertilizer; Qinhai 444 was the best cultilvar to get higher forage yield.3. Sowing date and N-fertilizer had significant effects on grain yield and its components. Sowing at late April gave higher performance in effective tiller number, seeds per panicle and thousand-grain weight. The effect of N-fertilizer on yield and its components showed same pattern, i.e., grain yield and its components increased with the increasing N rate. Significant difference was observed among N treatments. Applying N fertilizer at separate time showed better effectiveness under the same rate. Covered oats had higher grain yield than naked ones.4.The total and grain N-accumulation at anthesis and mature stages were remarkably affected by sowing date and N-fertilizer treatmeat with the latter had larger influence. Sowing at late April was the best time, and 100kg/hm2 was the best N rate to achieve higher total and grain N-accumulation. Among 4 cultivars, Qinhai 444 was the best; Ronald had least total N-accumulation, but its grain N accumulation was the second.5.Sowing date and N-fertilizer rate affected N-fertilizaer use efficiency. At mid April sowing date, no significant difference was observed among N treatmenets. When oats were seeded at late April and early May, 60kg/hm2 N rate could achieve the highest fertilizer NUE. With the same rate of N application, applying at separate time could also increase fertilizer NUE. Qinhai 444 gave the highest fertilizer NUE at 100kg/hm2 rate applied at separate times when seeded at mid April.6.Varietal characteristics was the chief facter affecting NHI. Ronald had the highest NHI under different sowing date and N-fertilizer treatment; late sowing resulted in lower NHI. Baiyan No. 2 and Ronald had the highest NHI when seeded at late April, while Baiyan No. 5 and Qinghai 444 gave the highest performances at mid April sowing date. N fertilizer also had significant influence on NHI. When N fertilizer was applied as base, NHI of Baiyan No. 5 and Qinghai 444 increased with the increasing N rates. Baiyan NO.2 and Ronald gave the highest NHI at 60kg/hm2 N-fertilizer.7.Sowing date and N-fertilizer had significant effects on N-allocation in stem, leaves and seed. The proportion of N-allocation in seed reduced with prolonged sowing date. N allocation to stem and leaves was the highest when seeded at early May. Increasing N-fertilizer could improve N-allocation to seed significantly. Without N fertilizer, more N was allocated to stem and leaves compared to N fertilizer application. Ronald had the highest N allocation to grain, while Qinghai 444 was the lowest. Baiyan No. 5 allocated most N to leaves, while Qinghai 444 had the highest peoportion N in stems.