Effect of abscisic acid applications on cold tolerance in chickpea (Cicer arietinum L.)

A series of field experiments were undertaken at three locations in Khyber PukhtunKhwa (KPK) Province, Pakistan to assess the effects of low temperatures and phytohormone applications on chickpea (Cicer arietinum L.) growth and yield. These trials showed that ABA application (10−4 M) to 40-day-old plants (before the first seasonal frost) offset low temperature-induced growth and yield depression at harvest (200-day-old plants) by up to 17%. These yield improvements were mainly due to an increase in the number of seeds pod−1. Growth room experiments were carried out under controlled environmental conditions to establish how foliar application of 10−4 M ABA to 40-day-old plants might improve seed production at harvest. The foliar application of 10−4 M ABA had no detectable effect on endogenous shoot or root ABA levels four-days after spraying or on biomass when plants were maintained in warm conditions. When exposed to night temperatures of −2 °C, however, the endogenous ABA levels increased dramatically in both control and ABA-treated plants, but this rise was more rapid after ABA application (p < 0.01); after 14 days, these plants had gained significantly more biomass than the unsprayed controls (p < 0.05). No evidence was found to suggest ABA affected the osmotic or water balance of plants, but parallel experiments have shown ABA reduced low temperature-induced cell damage. Analysis of the proteome of the shoot tissues of ABA treated and untreated plants by 2-Dimensional Gel Electrophoresis identified several proteins that are induced by low temperatures and/or by ABA application in chickpea and which may be involved in conferring cold tolerance. Attempts were made to establish the identity of these proteins using mass spectrometry but in all cases the results were ambiguous; a more complete protein data base for legumes is required before the function of these proteins can be inferred.

► Application of 10−4 M ABA had no effect on shoot or root ABA levels 4 days after spraying.
► ABA (10−4 M) had no effect on biomass 4 days after spraying in warm conditions.
► When exposed to temperatures of −2 °C, ABA increased in both control and ABA-treated plants.
► Several proteins were induced in chickpea by low temperatures and/or by ABA application.
► These newly induced proteins may be involved in conferring cold tolerance of chickpea.