A method is described for separating large and small pollen effectively from a heterogeneous mixture. This method potentially is applicable to separation of pollen grains of different ploidy levels, since “unreduced” 2n pollen is larger than normal pollen (n); it might then be used to increase the efficiency of a breeding program employing sexual polyploidization and to diminish crossing inefficiencies in interploid crosses.
Charles J. Simon and John C. Sanford
K.E. Maloney, W.F. Wilcox, and J.C. Sanford
`Titan' red raspberry (Rubis idaeus L.), highly susceptible to root rot caused by Phytophthora fragariae Hickman var. rubi Wilcox & Duncan (syns. P. erythroseptica Pethyb., “highly pathogenic” P. megasperma Drechs.), was planted in June 1990 in a silt loam naturally infested with the pathogen. Raked beds (0.36 m high) dramatically reduced disease incidence and severity relative to flatbed treatments. In contrast, metalaxyl at 372 mg·m-1 of row provided little benefit when applied to flat beds and provided consistently moderate but statistically insignificant effects when applied to raised beds. Relative to the flat bed system, primocane vigor was increased in 1992 by 16%, 190%, and 224% in the flat bed plus metalaxyl, raised bed, and raised bed plus metalaxyl treatments, respectively; total yields were increased by 7%, 231%, and 272% with these same respective treatment. The results indicate that raised-bed planting systems can provide substantial control of phytophthora root rot of red raspberries even when highly susceptible varieties are grown on otherwise marginal sites. Metalaxyl appears more effective as a supplement rather than substitute for raised beds under such conditions. Chemical name used: N- (2,6-dimethylphenyl) -N- (methoxyacetyl)alanine methyl ester (metalaxyl).
C.A. Weber, K.E. Maloney, and J.C. Sanford
C.A. Weber, K.E. Maloney, and J.C. Sanford
C.A. Weber, K.E. Maloney, and J.C. Sanford
The performance of 11 primocane fruiting raspberry (Rubus idaeus) cultivars was evaluated based on yield and fruit weight from the first three seasons compared to the eighth and ninth seasons, respectively. Plot vigor and cane density was evaluated in the eighth season. `Prelude', `Caroline', and `Heritage' did not show a decline in yield in the eighth season compared to the first three seasons. `Kiwigold', `Graton Gold' (sold as `Goldie'), `Watson' (sold as `Ruby'), `Autumn Bliss', `Anne, and `Amity' had substantial yield decreases from early production seasons ranging from -30% to -82%. `Kiwigold' had the highest yield of 4015 kg·ha-1 (3582.2 lb/acre) in the eighth season followed by `Caroline' at 3649 kg·ha-1 (3255.6 lb/acre), `Heritage' at 3614 kg·ha-1 (3224.4 lb/acre), and `Prelude' at 3591 kg·ha-1 (3203.9 lb/acre). Fruit weight did not vary significantly among years, but there were differences among cultivars. In the ninth season, `Ruby' had the largest fruit at 3.1 g (0.11 oz), followed by `Autumn Bliss' at 2.9 g (0.10 oz), and `Caroline' and `Prelude' at 2.8 g (0.10 oz). `Summit', `Goldie', and `Rossana' had the smallest fruit at 1.5 g (0.05 oz). `Goldie' was the most vigorous cultivar and `Anne' the least in the eighth season based on vigor ratings. `Rossana' had the highest cane density at 41.6 canes/m2 (3.86 canes/ft2). Seven of 11 cultivars had cane density of 32 canes/m2 (3.0 canes/ft2) or higher, which is sufficient to produce acceptable yields in cultivars suited to the region. Overall, `Prelude', `Caroline' and `Heritage' and its sports, `Kiwigold' and `Goldie', show the most potential for long production cycles in climates similar to western New York state.
S. Lius, R. Manshardt, D. Gonsalves, M. Fitch, J. Slightom, and J. Sanford
Twenty transgenic Carica papaya plants ('Sunset', Roclone 55-l) carrying the coat protein gene (cp) of papaya ringspot virus (PRV) strain HA 5-l have remained symptomless and ELISA-negative for 18 mo. after inoculation with Hawaiian PRV under field conditions. Control plants showed disease symptoms within 1 mo. after manual inoculation or within 4 mo. when aphid populations were the inoculum vectors. Trunk diameter was significantly greater in cp + plants (14.3 cm) than in PRV-infected controls (9.3 cm). Fruit brix, plant morphology, and fertility of cp + plants were all norm al. Segregation analysis in R1 seedlings indicated that 55-1 contains a single transgenic insertion site. PRV resistance in R1 plants was linked with the cp gene, although in some progenies, up to 50% of cp + plants developed mild PRV symptoms more than 3 mo. after inoculation. Preliminary tests suggest that this is not due to genesis of virulent mutant strains of PRV.
R. Manshardt, S. Lius, D. Gonsalves, M. Fitch, J. Slightom, and J. Sanford
Transgenic papaya lines carrying the coat protein gene (CP) of papaya ringspot virus (PRV) strain HA 5-1 display PRV reactions ranging from complete susceptibility (39-3 & 39-4), to slight delay in onset of symptoms (39-1) and attenuation of symptoms (60-3), to high-level resistance (55-1, 63-1). Normal Mendelian segregation of transgene expression was lost in R1 of 39-3 and 39-4, and inbred R1 60-3 gave an aberrant 1:1 ratio. R0 55-1 plants were resistant in the field (Hawaii) for 2 years following manual and/or aphid inoculation, and the high-level resistance remained stable in the R1 after repeated manual inoculations in the greenhouse and graft inoculation for up to 1 year (Cornell). However, inoculation with PRV HA-Oahu strain produced symptoms in some plants at Cornell (9% after 6 weeks) and in Hawaii (50% after 1 year). Two 55-1 and one 60-3 plant subsequently underwent remission of symptoms and became ELISA-negative (Hawaii). Transmission of PRV isolates from symptomatic 55-1 plants to other CP+ 55-1 bioassay plants was unsuccessful.
C.M. Ronning, S.P. Kowalski, L.L. Sanford, and J.R. Stommel
The Colorado potato beetle is a serious pest of the cultivated potato. Natural resistance has been found in a few wild species, including Solanum chacoense Bitter, in which resistance is attributed to the presence of foliar specific leptine glycoalkaloids. Production and accumulation of these compounds within S. chacoense varies widely and appears to be inherited in a quantitative fashion, but high leptine producing clones occur rarely. In the present study, 15 different accessions from various locations and altitudes of origination were analyzed for foliar glycoalkaloid content in order to determine the frequency and distribution of genes for leptine production/accumulation, and to see if we could find a center, or core, of leptine production. Leptines were detected in eight of the 15 accessions, and the amounts within each accession varied widely, but none of the individuals produced high amounts of leptine (defined as greater than 62% of total glycoalkaloids). All of the leptine-containing accessions originated from western Argentina. There was no relationship between elevational level and leptine, but there was a negative trend with total glycoalkaloids and elevation; this was due to levels of solanine and chaconine decreasing with increasing elevation. In addition, nine unidentified glycoalkaloids were detected, in very high proportions in some individuals and accessions. AFLP marker frequency and diversity were used to compare subpopulations of these accessions. AFLP markers revealed substantial diversity among clones. The relationship of marker distribution to glycoalkaloid content is discussed. The results raise interesting questions about glycoalkaloid biosynthesis and inheritance, and point the direction for new avenues of leptine and glycoalkaloid research.
Michael A. Fidanza, David L. Sanford, David M. Beyer, and David J. Aurentz
Fresh mushroom compost is a byproduct of the edible mushroom (Agaricus bisporus) industry and represents the composted growing substrate that remains after a crop has been harvested to completion. Thirty samples were obtained from commercial mushroom farms in southeastern Pennsylvania and sent to a laboratory for analysis to determine plant nutrient content, bulk density, and particle size distribution of fresh mushroom compost. Fresh mushroom compost had an average pH of 6.6, with an average carbon:nitrogen ratio of 13:1. Organic matter content averaged 25.86% (wet weight), 146.73 lb/yard3 (wet volume) or 60.97% (dry weight). For the primary macronutrients, average total nitrogen content averaged 1.12% (wet weight), 6.40 lb/yard3 (wet volume) or 2.65% (dry weight), phosphorus measured 0.29% (wet weight), 1.67 lb/yard3 (wet volume) or 0.69% (dry weight), and potassium was 1.04% (wet weight), 5.89 lb/yard3 (wet volume) or 2.44% (dry weight). Average soluble salt content was 13.30 mmho/cm (wet weight basis). However, on a per acre basis, the calculated sodium absorption ratio of 0.38 was considered very low. The average bulk density of fresh mushroom compost was 574.73 lb/yard3 (wet volume basis), and 91% of the material measured ≤3/8 inch in diameter as determined on a wet weight basis. Overall, fresh mushroom compost is suitable as a natural organic fertilizer and soil amendment for agriculture and horticulture.