The effects ofAlternaria solani andVerticillium dahliae on potatoes growing in Israel

Summary The effects of two major fungal diseases of potatoes growing in hot climates, early blight (Alternaria solani) and Verticillium wilt (Verticillium dahliae), were investigated in field trials. Large populations of clones were grown in the Negev, Israel in the Spring and Autumn seasons of three years, 1983, 1984 and 1985. Although symptoms of the diseases were seen in both seasons they were less severe in the Autumn. The effects ofA. solani on yield, when expressed as percent of the control plot yield were also less in the Autumn than the Spring. WithV. dahliae, however, the proportional effect on yield was greater in the Autumn. The decreases in yield associated with the two diseases were examined in terms of losses to the grower. The advantages of breeding for resistance/tolerance to these diseases were clear, emphasising the need for suitable screening techniques.     

Effect of storage period, cultivar and two growing locations on the processing quality of french fried potatoes

The source of raw potato tubers and the tubers’ duration of storage have a significant effect on color and texture of french fries. Controlling these variations is crucial to ensuring a consistent, high-quality end product. Russet Burbank and Shepody potatoes grown at two sites in Manitoba, Canada were stored for 9 and 11 months in 1994, and for 1 and 3 months in 1995, to determine the effects of short-term storage period, cultivar, and two tuber-growing locations on fry color and texture. French fry texture was measured by a puncture test, and peak force and peak deformation used as indices of textural quality. Large peak forces and deformations were assumed to be indicative of improved textural quality. Hunterlab L (lightness) value was used to determine fry color, higher values being associated with improved color quality. Fries processed from 11-month-old tubers had improved color and textural quality compared to those processed from 9-month-old tubers. Fries processed after 3 months tuber storage were darker in color but firmer in texture than fries processed from tubers after 1 month of storage. Differences in texture and color between the two cultivars were more evident with prolonged storage; fries processed from Russet Burbank potatoes were superior in texture and lighter in color than fries made from Shepody potatoes. With respect to site, fries processed from potatoes grown at Portage had better texture but darker color than those processed from Carberry potatoes. It was postulated that the calcium content of the soils may be responsible for both these results.     

The possibility of growing seed potatoes in the area of Mount Katerina in Sinai mountains

Summary The Mount Katerina area is isolated, in the middle of the Sinai Desert, and its peak is at an altitude of 2647 m. Trapping with yellow water traps showed that winged aphid populations are small and active mainly in the spring and only until May. Virus-tested tubers of cv. Up-do-Date were planted on 18 May and harvested on 27–29 September. No PLRV, PVY or PVX infection was detected in 319 haulm samples and in 96 progeny tubers. When the Mt Katerina tubers were planted the next spring, they yielded 11% and 7% more than imported and Golan seeds respectively (non-significant differences) and emerged to a greater extent. The results indicate that the Mt Katerina area may be suitable for growing high quality seed-potatoes. Supported in part by BARD Project US-3399-80. Contribution No 815-E, 1983 Series.     

A method for growing potatoes by combining water culture and pot culture techniques

A combined water culture and pot culture technique was developed for the study of the K nutrition of potatoes. The water culture technique permitted control of the K nutrient supply while the pot culture technique provided support for plant growth and for tuber development in a low K medium. Both plant growth and tuber quality reflected the K supply of the culture solution.     

Effect of transplant container volume and growing season length on field performance of micropropagated potatoes

Micropropagation is a tissue culture technique adapted for the rapid multiplication of disease-free seed stocks. Procedures for propagating potatoes in the laboratory and acclimating plantlets in the greenhouse are available, but information on cultural practices for maximizing tuber yield of plantlets when transplanted to the field is lacking. Centennial Russet and Russet Burbank plantlets were transferred from culture jars to three sizes of transplant containers for establishment under greenhouse conditions before transplanting to the field. Length of field growing season was varied by using two transplant dates and two vine kill dates. Survival of field transplanted plantlets was above 95 percent in both 1983 and 1984. Cultural practices significantly affected the tuber yield of plantlets of both cultivars. Total yield and yield of tubers larger than 35 mm in diameter increased with increasing transplant container volume. Transplant container volume had no effect on the yield of tubers less than 35 mm in diameter. Highest total yields and tuber production per plantlet for both Centennial Russet and Russet Burbank were obtained from the longest growing season (early transplant date with late vine kill). Yield of Russet Burbank plantlets increased more in response to a longer growing season than did Centennial Russet.     

Growth regulators,photoperiod, and flowering in potatoes

The effect of 25 ppm gibberellic acid (GA₃), 7,500 ppm Gapol^(R) (0.4% molybdate; 0.42% cobalt; 0.56% tungstate; 2.84% borax; 4 ppm indoleacetic acid; 4 ppm naphthyltalamic acid; and 2 ppm ethylenediaminetetraacetic acid) and of two photoperiods (12 and 18 h daily) on flowering of potato cv Marijke was studied under greenhouse conditions. GA³ specifically reduced the number of days required for flowering, and Gapol^(R), or long days, favored bud retention. When combined, only a slight additive effect was observed. In most cases spraying the products on plants subjected to long days resulted in an increase in the number of floral buds, but their attachment to the plant was mainly influenced by the presence of Gapol^(R).     

Protein,nonprotein, and total nitrogen in seedlings of potatoes

Analyses for secific gravity, total solids, total nitrogen, protein nitrogen, and nonprotein nitrogen are reported for 73 seedling samples grown in Maine, and for 10 selections grown in Idaho. The interactions between the various constituents, as indicated by regression analysis, are discussed. These samples indicate a potential for breeding a variety of potato with a higher than average protein content, but further work is necessary to determine the inheritance pattern. This work is in progress.