established that piquin peppers present high genetic variability (among and within populations) with high phenotypic plasticity ( Castañón-Nájera et al., 2014 ). Differences in plant characteristics, fruit and leaf morphology, seed germination, and pathogen
the medium. Table 1. Isolates of P. aphanidermatum , P. irregulare , and P. ultimum obtained from infected ornamental plants in Michigan, and evaluated in vitro for sensitivity to etridiazole. P. aphanidermatum isolates 106 and 319 and P
Abstract
Pollen of Psidium guajava L. germinated at pH levels of 4.5-7.0 up to 33 hr after anthesis. Germination of fresh pollen was depressed at pH 7.0 but germination of older pollen was enhanced. Pollen 1-2 days old which failed to germinate in vitro still induced fruit set when used in pollination, indicating that it was still functional.
Pollen germination in vitro of the species studied varied considerably. Generally, pollen of species with high chromosome numbers germinated poorly.
Pollination studies indicated partial self incompatibility in all species studied. Reciprocal interspecific crosses showed pronounced differences in compatibility.
Abstract
In vitro germination of pollen from almond (Prunus amygdalus Batsch), peach [P. persica (L.) Batsch], apricot (P. armeniaca L.), plum (P. salicina Lindl.), and sweet cherry (P. avium L.) after freezing in liquid nitrogen was similar to unfrozen pollen. In vivo germination of frozen pollen was confirmed with apricot and cherry.
assistance of Iris Sashitzky, ARO. Mention of trade products does not imply endorsement or recommendation over similar products not mentioned. The cost of publishing this paper was defrayed in part by the payment of page charges. Under postal regulations
New Jersey Agricultural Experiment Station Publication no. D12145-7-62, supported by state funds. We thank Joseph C. Goffreda for helpful discussions. The cost of publishing this paper was defrayed in part by the payment of page charges
Abstract
The effect of high temperature on pollen viability and fruit set was studied in a Sicilian landrace of Lagenaria siceraria (Mol.) Standi. In vitro germination of pollen from flowers of plants exposed for 7 hr to either 28° or 33°C was not significantly different from that of pollen from untreated, greenhouse-grown plants. A single 7-hr exposure of plants to 38° completely inhibited germination of pollen from flowers reaching anthesis either immediately following the treatment or 24 hr later, and substantially reduced germination of pollen from flowers reaching anthesis at 48 or 72 hr after treatment. Pollen from flowers subjected to 38° for 7 hr failed to germinate and grow into styles of untreated female flowers and failed to induce fruit set. Exposure of plants to 38° for 4 hr reduced in vitro pollen germination by 55% to 75%, but a 2-hr treatment at 38° had no detectable effect on pollen viability.
Abstract
Seven assays (hanging-drop slide and agar-plate germination, acetocarmine, three tetrazolium-based stains, and Alexander’s staining procedures) were used to estimate pollen viability in Prunus armeniaca L., P. avium L., P. dulcis Webb, P. persica (L.) Batsch, and P. salicina Lindl. The two in vitro germination tests (hanging-drop and agar-plate) were the most reliable and were highly correlated (r = 0.96). The pollen staining procedures were not reliable or consistent and were not positively correlated with the in vitro assays. Acetocarmine and Alexander’s stains stained dead pollen.
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The genetics of the ability of tomato pollen to germinate and grow in vitro under low temperature was investigated in two crosses namely “Resista” × “Hilda” and “Resista” × “Monita”. In each cross the following generations were utilised: F1, F2, BC1 and BC2, and their reciprocals, along with the parents. Pollen was placed on microscope slides having cavities filled with a liquid nutrient medium (water, 10% sucrose and 50 ppm boric acid) and allowed to germinate and grow for six hours at 15° C and then killed with acetocarmine. Germination rates and pollen tube length were determined and analyses on a genetic model allowing only for additive and dominance gene effects.
For pollen germination rate both additive and dominance gene effects were significant while for tube length only the additive effects were. Dominance was towards lower rates of germination. At least three genes control pollen germination rates while seven or more are involved in pollen tube length determination.