Dry Matter Production and Nitrogen Utilization by Six Potato Cultivars

The rate and duration of tuber growth largely determines the final potato (Solanum tuberosum L) tuber yields. Cultivars that continue leaf development and nutrient uptake while maintaining maximum tuber growth rates may have higher final tuber yields, yet different N requirements. The objective of this study was to obtain information relating plant growth rates to N availability for selected potato cultivars. Total dry matter accumulation, and N assimilation patterns of indeterminant cultivars, 'Russet Burbank', 'Lemhi Russet, 'Centennial Russet', and one advanced selection A66107-51, were compared-with that of two determinant cultivars 'Pioneer' and 'Norgold Russet', at three N levels. Cultivars were grown in a field experiment on a Portneuf silt-loam soil (Xerollic Calciorthids). High available soil N levels at planting delayed the linear potato tuber growth period 7 to 10 days but had minor effects on the time of tuber initiation for the indeterminant varieties. Maximum tuber growth rates (tuber bulking) were 900 to 1,300 kg/ha/day. A66107-51 was superior in N-use efficiency to the other cultivars. Between 70 and 100% of the total available N was utilized by this cultivar in producing high yields. This information may be used to select lines and cultivars that will optimize production. A knowledge of plant growth and N uptake rates can improve the fertilizer recommendations for each cultivar