Annals of Botany 87: 517-522, 2001
© 2001 Annals of Botany Company
The Importance of Light Intensity for Pollen Tube Growth and Embryo Survival in Wheat x Maize Crosses
New Zealand Institute for Crop and Food Research Limited, Private Bag 4704, Christchurch, New Zealand Soil, Plant and Ecological Sciences Division, PO Box 84, Lincoln University, Canterbury, New Zealand Botany Department, University of Otago, PO Box 56, Dunedin, New Zealand
Received: 22 August 2000 ; Returned for revision: 20 November 2000 . Accepted: 17 December 2000
The success of Triticum aestivumxZea mays crosses, used to produce wheat doubled haploids, is influenced by light intensity. To examine the basis for this response, pollen tube growth, embryo survival and indicators of photosynthetic rate were measured in two wheat cultivars (Karamu and Kotuku) crossed with maize at two irradiance levels (250 or 750 µmol m-2s-1, PAR). Pollen tube growth was significantly affected by light intensity in Karamu plants but not in Kotuku plants, despite both cultivars being pollinated by the same maize source. The percentage of pollen tubes reaching the cavity between the ovarian wall and integuments, or in the micropyle of Karamu plants at high light intensity (65%) was nearly three-times greater than that at low light intensity (22%). Thus, either low light intensity can affect the maternal wheat plant in a way that inhibits pollen tube growth and/or high light intensity may promote pollen tube growth in Karamu plants. Significant differences in rates of electron transport in plants grown at the two light intensities indicated that the rate of photosynthesis may also have an effect on pollen tube growth. These results have importance for improving the efficiency of wheat x maize crosses and other wide cereal crosses. Copyright 2001 Annals of Botany Company
Intergeneric hybridization, light intensity, pollen tube growth, embryo survival, Triticum aestivum, wheat,Zea mays , maize