Effect of Red Norland Potato Plant Spacing On Tuber Yield and Quality.

Potato tuber yields and quality may be limited by current potato plant spacing practices, which are 36 inch row spacing between rows, with nine inch in-row plant spacing. Current potato plant spacing does not fully utilize sunlight for photosynthesis. The objectives of this study were to determine the effect of plant and row spacing on red potato yield and quality, and compare weed populations and density among different plant and row spacing. The study was conducted using, with five treatments replicated three times. The treatments were 23, 30.5, 38, and 45.5 cm equal distance spacing, and a control treatment of 91.5 cm row spacing with 23 cm in-row spacing. Plot size was 4.5 x 3 m, and plots were hand planted and harvested. Visual observation of potato canopies showed that more dense plant spacing resulted in a more rapid canopy closure which resulted in less weed pressure. The average tuber size ranged from 47.6 to 63.6 g. The 23 cm spacing had the smallest average tuber size, and the 45.5 cm and control treatments had the largest tuber size. The result of higher density planting is a smaller tuber size which is more desirable in red potatoes. The average tuber yield ranged from 32.0 Mg ha­^-1 for the control to 60.8 Mg ha^-1 for the 23 cm spacing treatment. The more efficient utilization of sunlight by using equal distance spacing does increase yield. The increased plant density resulted in more tubers per hectare which attributed to a yield increase.  The advantage of high density planting is a smaller more marketable tuber size and a higher yield than conventional practices.  The more rapid canopy closure of high density potatoes results in fewer weeds and less need for herbicide application.