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  • Author or Editor: David Cross x
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Impatiens (Impatiens wallerana Hook.f.) flower seeds are believed to be sensitive to storage temperature and humidity conditions. A study was conducted to evaluate seed quality changes occurring during a 1-year period of storage under various temperature and humidity combinations. Four seed lots of `Super Elfin Red' and `Super Elfin White' impatiens were studied. Constant humidity treatments were obtained using saturated salt solutions; 15% relative humidity (RH) with LiCI, 25% RH with KAc, 33% RH with MgCl2, and 43% RH with K2CO3. Constant temperature treatments were 5, 15, and 22C. At 3-month intervals, replicate samples were sown in plug flats in the greenhouse. Seed quality was evaluated as the percentage of usable seedlings 21 days from sowing. Rapid deterioration of seed quality was seen under high temperature and high humidity storage conditions. Seeds became less sensitive to humidity at 5C. Conditions of 20% to 25% RH and 5C are recommended for impatiens seed storage.

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Macadamia is partially self-incompatible and cross-pollination is considered important to improve yields. However, questions remain regarding the importance of self- vs. cross-pollination, and subsequently whether managed pollinators are useful in commercial orchards. Pollinators play a key role in cross-pollination, but for self-pollination, the protandrous florets might also benefit from the movement of potentially more viable self-pollen among florets, racemes, and trees through pollinator movement. There is also a lack of information on pollination deficits throughout orchards and whether by increasing the intensity of cross-pollination, final nut yield is limited by within-tree resource allocation. Using caged and bagged racemes on three cultivars, we found strong evidence for self-pollination, but no evidence that hand moving self-pollen within racemes, between racemes, or between trees improved final nut set. In all cases, hand cross-pollinated racemes yielded significantly more nuts. Hand cross-pollinated racemes also produced significantly more developed nuts than open-pollinated racemes (all racemes were exposed to pollinators). However, by increasing the intensity of hand cross-pollination per tree, we showed that resource allocation probably overinflates these measures of pollination deficit in macadamia. Despite this, our findings point to an opportunity to increase yields through additional cross-pollination, as high-intensity hand cross-pollination of flowering racemes within trees still resulted in increased nut set. Although self-pollination can occur in macadamia, to optimize yield potential, strategies to maximize cross-pollination should be adopted.

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