Genotypes differences in sap bleeding rate among diverse rice cultivars under different soil moisture conditions

Issue Date

7-2018

Abstract

Soil water uptake, one of the key determinants for drought adaptation is largely dependent on root system developmental responses to water deficit. Bleeding sap is a manifestation of root pressure related to physiological traits of the root system. This study evaluated the sap bleeding rate of eight rice genotypes with diverse root responses under various soil moisture conditions and determined the effects on yield. The genotypes were established in the field in split plot design in RCBD under two water stresses: continuously waterlogged (CWL) and progressive drought (PDR) stress and grown until maturity. Xylem sap sampling was done at flowering stage between 7:00-9:00am using pre-weighed cotton towel placed on the cut surface of the stump and wrapped in plastic film with rubber band. The cotton was weighed again after 1 hr and the increase in weight was used to compute the sap bleeding rate. There were significant interactions between genotypes and water stress on sap bleeding rate. Relative to CWL, rice varieties DRS63 and NSIC Rc158 had significant increase in sap bleeding rate by 31.1 and 12.5% under PDR while the other genotypes showed significant reductions ranging from 46.8 to 96.3%. Drought significantly reduced shoot biomass and yield in most genotypes except in DRS63, KDML 105, Kinandang Patong and YTH304, relative to CWL control. Yield positively correlated with sap bleeding rate under drought while the two traits were negatively correlated under CWL. The results indicate that higher sap bleeding rate under drought during flowering may imply that some genotypes adapted to drought (e.g. DRS63) may have the ability to efficiently regulate soil water uptake during earlier growth stage and make it readily available at critical stage such as during the post flowering drought and hence increase in sap bleeding rate. Further data analysis and studies are being conducted to validate the initial findings.

Source or Periodical Title

Philippine Journal of Crop Science

ISSN

0115-463X

Volume

43

Issue

Supplement no. 1

Page

67-68

Document Type

Article

Language

English

Subject

Oryza sativa L.; Rice varieties; Drought-tolerant plants

En – AGROVOC descriptors

ORYZA SATIVA; VARIETIES; GENOTYPES; SAP; NUTRIENT TRANSPORT; WATER UPTAKE; DROUGHT; SOIL; SOIL WATER CONTENT; WATERLOGGING

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