8. Maize

Maize (Zea mays L.) yield is often restricted by low soil water availability, particularly late in the growing season during seed fill. Large genetic variation has been identified among maize hybrids in stomata closure both with early soil drying and elevated vapor pressure deficit. Little follow-up research has yet to be done concerning expression of early partial stomatal closure with soil drying. On the other hand, substantial research has been on the limited-transpiration trait in the release of commercial maize hybrids as it relates to the initiation of partial stomata closure at vapor pressure deficit. In the commercial AQUAmax hybrids for dryland regions, the sensitivity to vapor pressure deficit occurred at about 2 kPa. Studies of these hybrids showed that the vapor pressure deficit threshold was related to the sensitivity of transpiration rate to a screening treatment of silver ion aquaporin inhibitor.