Influence of Trickle Irrigation Emitter Placement on Yield and Grade Distribution of Potatoes

A 2-year study on the influence of trickle irrigation on the yield response of potato (Solanum tuberosum L. cv. Norgold Russet `M') was conducted at Lubbock, Texas. The objective was to evaluate the effects of trickle emitter placement on yield of #1, #2, marketable, cull, small, and total tubers. Trickle emitter lines were positioned 1) on the soil surface, 2) with the tuber pieces (4-inch depth), and 3) at S-inch depth. Irrigation was applied daily to replenish the water lost the previous day based on pan evaporation and crop coefficients. Marketable tuber yield was ≈ 8.9 to 11 tons/acre for all irrigation treatments. In both years, the proportion of misshapen potatoes (culls) was significantly greater for the S-inch depth irrigation treatment than for the surface or 4-inch depth treatments (2.9 vs. 0.71 and 0.67 tons/acre and 3.3 vs. 0.89 and 1.16 tons/acre, respectively). The misshapen tubers were directly influenced by trickle emitter placement and indirectly influenced by temperature differences within the tuber zone.

RESISTANCE TO THE COLORADO POTATO BEETLE AND GREEN PEACH APHID IN INTERSPECIFIC SOLANUM HYBRIDS.

Resistance to the Colorado potato beetle (CPB) and green peach aphid (GPA) would be valuable if it could be effectively transferred from wild potato species to the cultivated potato. Eighteen diploid interspecific hybrids have been developed using Solanum tuberosum Gp. Tuberosum haploids (2n = 2x = 24) and the diploid wild species S. berthaultii (ber), S. chacoense (CHC), S. jamesii (jam), and S. tarijense (tar). Twenty-five genotypes per family were screened for resistance to CPB and GPA. Feeding trials were carried out on intact leaves. The degree of resistance to CPB was determined by the stage of instar development and weight of larvae after a four day feeding period; resistance to GPA was evaluated by aphid reproduction and survival after a fifteen day feeding period. Highly CPB or GPA resistant clones, compared to `Norgold Russet',, have been identified thus far. Some clones express high levels of resistance to both CPB and GPA. Crosses between resistant clones and S. tuberosum will be carried out at the diploid level in an attempt to combine resistance with good tuberization qualities.

RESISTANCE TO THE COLORADO POTATO BEETLE AND GREEN PEACH APHID IN INTERSPECIFIC SOLANUM HYBRIDS.

Resistance to the Colorado potato beetle (CPB) and green peach aphid (GPA) would be valuable if it could be effectively transferred from wild potato species to the cultivated potato. Eighteen diploid interspecific hybrids have been developed using Solanum tuberosum Gp. Tuberosum haploids (2n = 2x = 24) and the diploid wild species S. berthaultii (ber), S. chacoense (CHC), S. jamesii (jam), and S. tarijense (tar). Twenty-five genotypes per family were screened for resistance to CPB and GPA. Feeding trials were carried out on intact leaves. The degree of resistance to CPB was determined by the stage of instar development and weight of larvae after a four day feeding period; resistance to GPA was evaluated by aphid reproduction and survival after a fifteen day feeding period. Highly CPB or GPA resistant clones, compared to `Norgold Russet',, have been identified thus far. Some clones express high levels of resistance to both CPB and GPA. Crosses between resistant clones and S. tuberosum will be carried out at the diploid level in an attempt to combine resistance with good tuberization qualities.