Environmental Control of Moisture Content and Viability in Schlumbergera truncata (Cactaceae) Pollen

Abstract

The objective of this study was to determine the effects of temperature, relative humidity (RH), and storage duration on moisture content and viability of Schlumbergera truncata (Haworth) Moran (Thanksgiving cactus) pollen. Pollen viability was assayed by the fluorochromatic reaction (FCR) test, percentage fruit set, and numbers of viable seeds per fruit. Pollen moisture content was ≈38% at anthesis but decreased to ≈12% by 1 day after anthesis and remained low (10% to 12%) until flowers senesced. Pollen viability was 85% on the day of anthesis, remained at ≈80% from 1 to 3 days after anthesis, and decreased to ≈65% when flowers began to senesce. When pollen was stored for 4 days at 21 °C, moisture content decreased to 1% for pollen stored at 1% RH but increased to 33% for pollen kept at 100% RH. Fruit and seed yields obtained with pollen stored for 4 days at 21 °C and 15%, 28%, or 52% RH did not differ significantly from those obtained with fresh pollen. Pollen stored for 4 days at 21 °C and 1%, 68%, or 90% RH produced fewer fruit and seeds than fresh pollen. Fruit and seed yields obtained with pollen stored 20 days at 21 °C and 15% or 28% RH were similar to yields obtained with fresh pollen. Pollen with ≤23% moisture content that was stored at -18 °C for ≥24 hours retained its original viability (≈85%) whereas pollen with a high (32% to 34%) moisture content exhibited low (≈22%) viability after storage at -18 °C for ≥24 hours. Pollen stored for 140 days at 4 or -18 °C and 13% to 51% RH yielded as many viable seeds per fruit as fresh pollen. Although S. truncata pollen is tricellular, it tolerates desiccation to a low (4%) moisture content and can be stored at temperatures below 0 °C.