Partitioning of photoassimilates by potato plants (Solanum tuberosum l.) as influenced by irradiance: II. Partitioning patterns by four clones grown under high and low irradiance1

This paper is the second in a three-part series describing the influence of varied irradiance on growth and photoassimilate partitioning by potato plants. Four clones (Russet Burbank, Lemhi Russet, A66107-51, and A6948-4) were grown under two light regimes: a) high light levels (HL) of 500 to 1200 μE m^-2 s^-1, varying with changes in natural sunlight and time of day, and b) low light levels (LL) at approximately one quarter of high light (21 to 28%). Three weeks after tuber initiation, the most recently-matured leaf was labelled with¹⁴CO₂, and plants were harvested: 1) one day after labelling, and 2) two weeks after labelling. Plants of all clones responded to the low light levels in a similar way by: 1) changing some morphological characteristics, 2) decreasing biomass accumulation and tuber yield, and 3) changing the sink-source relationship by promoting growth of leaves and stems at the expense of tubers. However, there were evident clonal differences in reactions to growth under low light; e.g., Lemhi Russet appeared to be most sensitive to light stress, while clones A66107-51 and A6848-4 were much less sensitive. No matter what the prior light history (HL or LL), clone A6948-4 was able to maintain higher rates of photosynthesis than the other clones at all light levels between 200 and 1200 μE m^-2 s^-1. This study showed that the potential exists to breed for cuttivars that can maintain higher rates of photosynthesis and higher tuber yield under low light levels.     

Sensory and cooking quality of individually film wrapped potatoes

Newly harvested Russet Burbank potatoes were cured for 3 weeks at 15.5 C. The cured potatoes were individually film wrapped either immediately, or stored at 7.2 C for 12 weeks and then film wrapped. The film wrapped potatoes stored at 20 C were compared with nonwrapped potatoes stored at 7.2 C or 20 C for cooking time and various sensory characteristics. The sensory and cooking characteristics of the film wrapped potatoes stored at 20 C were better than the baking characteristics of nonwrapped potatoes stored at 20 C but not at 7.2 C. Individual film wrapping of potatoes significantly preserved the baking and cooking quality of potatoes during storage at 20 C, 60% RH.     

Comparative growth analysis of Russet Burbank potatoes at two Idaho locations

Detailed growth analyses were conducted with Russet Burbank potato to provide validation and parameterization data for a computer growth model being developed cooperatively at the University of Idaho and University of California, Davis. At each of two locations (Aberdeen and Kimberly, Idaho) plants were sampled seven times at about two-week intervals. Plants were separated into individual leaf blades, petioles, internodes, tubers, and roots. Leaf area indices and leaf elevation angles were determined in 20 cm strata. Plants at Kimberly emerged approximately 10 days prior to those at Aberdeen. At both locations, the increase in total dry weight was curvilinear for 30–40 days after emergence and then was linear until the end of the study. The maximum top weight per hill was slightly higher at Aberdeen, but near-maximum values occurred for much longer at Kimberly. Total leaf area at Aberdeen reached a maximum of approximately 4.0, while the maximum at Kimberly was 5.5. Root dry weight reached a maximum much earlier at Kimberly and the change in root dry weight paralleled that of tops in both places. Tuber initiation occurred approximately 19 June at both locations. Following an initial increase, tuber number/hill decreased for several weeks. Final tuber numbers per hill were approximately six at Aberdeen and 12 at Kimberly. Dry weight per tuber showed a curvilinear increase for 20–30 days and then was constant at 0.68 and 0.37 g/tuber.day at Aberdeen and Kimberly, respectively. Bulking rates were 17 and 21 g/m².day. Final yields were 39 T/ha at Aberdeen and 49 T/ha at Kimberly. The higher final tuber yield at Kimberly was the result of a higher rate of bulking and a longer leaf area duration.