Physiological and phytochemical properties of Tinnevelly senna, Cassia angustifolia Vahl: Responses to drought, nitrogen and deflowering.
Item
-
Title
-
Physiological and phytochemical properties of Tinnevelly senna, Cassia angustifolia Vahl: Responses to drought, nitrogen and deflowering.
-
Identifier
-
AAI9908349
-
identifier
-
9908349
-
Creator
-
Ratnayaka, Harish.
-
Contributor
-
Adviser: Dwight T. Kincaid
-
Date
-
1998
-
Language
-
English
-
Publisher
-
City University of New York.
-
Subject
-
Biology, Plant Physiology | Biology, Ecology | Biology, Botany
-
Abstract
-
Experiments were conducted to evaluate the promise of Tinnevelly senna as an alternative crop for stressful agroecosystems, and to identify component technologies that would increase leaf sennoside yield. Effects of drought, foliar nitrogen spray, crop type and deflowering on net photosynthesis {dollar}({lcub}\rm P{rcub}\sb{lcub}net{rcub}){dollar} and sennoside A and B yields were investigated.;Net photosynthesis was completely suppressed at leaf xylem water potential of {dollar}-{dollar}2 MPa. Long term drought reduced leaf biomass and number of stomata per plant by 77% and 74%, respectively, mainly due to defoliation. Foliar applied nitrogen spray increased P{dollar}\sb{lcub}net{rcub}{dollar} in both watered and droughted plants. Leaf yield was 156% increased by foliar nitrogen application, in the watered plants, but was unaltered in the droughted plants. Foliar nitrogen spray decreased stomatal density on the adaxial surface but increased it on the abaxial surface. Trichrome density was increased by drought but decreased by foliar nitrogen spray. Among the crop types, P{dollar}\sb{lcub}net{rcub}{dollar} was highest in seedlings followed by cuttings and ratoon, while leaf yield was highest in seedlings followed by ratoon and cuttings. Deflowering reduced P{dollar}\sb{lcub}net{rcub}{dollar} by 20% but increased the leaf yield by 63% compared to the flowering plants. In all the treatments, P{dollar}\sb{lcub}net{rcub}{dollar} was closely associated with leaf chlorophyll concentration.;Short term drought increased sennoside A+B concentration (% dw) in the dried leaves. Long term drought, after the drought-induced morphological changes occurred, did not influence sennoside A+B concentration. Foliar nitrogen spray decreased sennoside A+B concentration in both droughted and watered plants but increased sennoside yield per plant by 142%, only in the watered plants. Ratoon had the highest sennoside A+B concentration followed by seedlings followed by ratoon and cuttings. Deflowering increased the sennoside A+B concentration by 25%, and doubled the sennoside yield per plant. Youngest leaves had the highest sennoside concentration (% dw). Sennoside yield per plant was more a function of leaf biomass than the sennoside concentration. Short term drought, foliar nitrogen spray, ratooning, deflowering and picking of young leaves are promising component technologies for field-research toward increasing sennoside yields.
-
Type
-
dissertation
-
Source
-
PQT Legacy CUNY.xlsx
-
degree
-
Ph.D.
