fvsu-009• White Potato

White potatoes, are one of the most valuable food crops after maize, rice and wheat. They rank fifth in acres under cultivation, fourth in production tonnage, and are cultivated in about 130 countries where three-fourths of the world population lives. In the U.S. 24.9 million tons of white potatoes were produced from 1.4 million acres in 1996. Although the white potato is considered a cool-season crop, its production is extending to warm climates and subtropical environments.

White potatoes are a short-duration, high cash value vegetable crop and bring quick returns to the grower. With a longer shelf life than other vegetables, they are easier to store and remain available over a longer period of time. White potatoes are generally superior in energy and protein production per unit area, and potato proteins are also rich in essential amino acids. They are also nutritious and rich in dietary fiber, minerals and vitamins, particularly vitamin C. Recent research also shows that potatoes are a good source of antioxidants known to fight disease-causing agents in the body.

Challenges

In South Georgia, mild temperatures during late winter and early spring are conducive to good potato growth; however, less than 1,000 acres are under cultivation in Georgia. Major problems limiting production are a lack of adapted cultivars that tolerate heat stress, high cost of good quality, disease-free seed potatoes (accounting for 25% to 60% of total production cost), high supplemental irrigation costs, and several marketing constraints. With the location of a major potato snack food manufacturing plant in Middle Georgia, there is excellent potential for commercial potato production, provided suitable cultivars are identified for the soil-climate complex in this region.

Potential genotypes for spring cultivation need evaluation for desirable agronomic characteristics such as early emergence, rapid leaf area development, early tuberization, faster bulking rates, suitability for the chipping industry and consumer acceptance. The challenge is to identify potato cultivars that are adapted to a short growing season, and have high dry matter content/high specific gravity. There is also need to reduce potato production costs, particularly seed potatoes, and, thus, increase profits.

Current Research

Agricultural Research Station scientists at Fort Valley State University have been involved in potato research in cooperation with USDA/ARS, Beltsville, MD, since 1982 and have evaluated about 150 genotypes. Current research focuses on:

Evaluating yield and quality of adapted potato cultivars. Twelve potato cultivars known for high yields and traits preferred by the potato processing industry were field tested for 3 years. The average yield ranged from 9.9 t/ac in 1996 to 22.1 t/ac in 1997 (national average 17.1 t/ac). Four red-skinned cultivars, Red La Soda, Red Dale, Chieftan and La Rouge gave yields between 9.9 and 25.1 t/ac, and appeared suitable for production in Middle Georgia. The specific gravity (an indirect measure of starch content) of fresh tubers ranged from 1.059 for La Rouge to 1.082 for Chieftan and Atlantic. Thus, the specific gravity of these tubers is near the minimum acceptable for the potato processing industry.

Evaluation of potential advanced breeding lines. Several advanced breeding lines have been evaluated for agronomic performance in comparison to cultivar Superior over the last three years. The yield of advanced breeding lines varied between 11.1 and 21.1 t/ac. Two lines, BO856-4 and BO852-7 appeared promising for production in Middle Georgia. The specific gravity of fresh tubers ranged from 1.059 for control cultivar Superior to 1.069 for selection B0856-4. In both studies, tuber yield was highly correlated to biomass and harvest index between 46 and 72 days after planting.

Seed plot technique. In warm climates, clonally propagated potatoes decline rapidly and yields decline unless seed is imported from cool climates for each crop. This practice is expensive for limited-resource farmers. An alternative method called Seed Plot Technique is used for raising seed potatoes in some subtropical regions. Good disease and blemish-free tubers are saved and stored at 4-5° C for planting in the next season. This method may be used without renewing the seed stock for as long as plant vigor is not lost and disease and pest organisms have not built up to levels to cause significant yield reduction. In this technique, potato plots set aside for seed are sprayed regularly to keep aphid population under control and foliage is removed a few days before harvesting.

Researchers retained Red Pontiac potato seed tubers from the 1996 spring crop and planted them in the spring of 1997. Yields from "new" Red Pontiac and "old" Red Pontiac potatoes were 19.5 and 19.8 t/ac respectively.

Estimated Cost of Cultivation and Returns Analysis

The estimated cost of potato production is about $1,365/acre. Gross return per acre (assuming a price of $0.20/lb. for good, marketable yield and 0.10/lb. for B and C grade tubers) can vary from $1,590 in a poor crop season to about $3,900 in a good crop season.

Future Research

Researchers will continue to evaluate more adapted cultivars to select for tolerance to heat stress, higher marketable yield, and tubers with specific gravity of more than 1.1 considered desirable for chipping purposes. Researchers will also explore cost-saving methods and the feasibility of two crops in a year, as well as developing efficient crop management practices that minimize drought and heat stress, increase nutrient use efficiency and make white potato production sustainable and profitable for Georgia farmers and home gardeners.