Effects of Water Stress on Pollen of Phaseolus vulgaris L.

Abstract

Abstract Pollen of plants of Phaseolus vulgaris L. ‘Red Mexican’ is affected adversely by water stress. The critical stress period occurs 10-13 days after emergence, during the transition from the vegetative to the reproductive phase of development. The transition phase is characterized by the presence of tiny green buds (>0.5-2.0 mm in length), bearing anthers that contain tetrads or free microspores. Pollen abortion of plants stressed during the transition phase is significantly higher than that of pollen from nonstressed plants or from those stressed during later phases of reproductive development. The percentage of pollen germination and total pollen production also are reduced in transition phase-stressed plants. Exine development is abnormal. This abnormal development is particularly interesting because the exine is regarded as so genetically stable that it is regularly used for species identification. Results of these experiments raise questions about the infallibility of identifications, since an environmental stress (such as water) imposed at a critical time of gametophytic development can markedly alter exine patterning.