Physiological basis of barley yield under near optimal and stress conditions

Abstract

Average barley yield fall below its potential due to incidence of stresses. Water stress is the main environmental factor limiting yield. The component a priori more sensitive to most stresses is the amount of radiation absorbed. The effect of stresses influence on the total amount of radiation absorbed by barley crop during its vegetation and the photosynthetic efficiency of radiation conversion. Growth inhibition is accompanied by reductions in leaf and cell wall extensibility. Grain yield under drought conditions is source limited. Supply of assimilates to the developing inflorescence plays a critical role in establishing final grain number and grain size. Grain weight is negatively affected by drought, high temperature, and any other factors that may reduce grain filling duration and grain filling rate. Awns and glaucousness confer better performance of barley under drought stress conditions. Barley responds with an increased accumulation of a number of proteins when subjected to different stress inducing cell dehydration. Screening techniques that are able to identify desirable genotypes based on the evaluation of physiological traits related to stress evasion and stress resistance maybe useful in breeding barley for resistance to stress, particularly drought stress. Crop management and breeding can reduce the incidence of stress on yield. The effect of these practices is sustained by an understanding of their physiology. In this paper the physiological basis of the processes determining barley yield and the incidence of stresses on photosynthetic metabolism that determine grain yield of barley is discussed. .

Prinos ječma je najčešće niži od njegovog proizvodnog potencijala zbog delovanja niza nepovoljnih biotičkih i abiotičkih činilaca, čije se negativno delovanje naziva stres. Deficit vode je najčešći uzrok smanjenja prinosa. Stres se prvenstveno manifestuje u smanjenju apsorbovane sunčeve energije tokom vegetacije i efikasnosti njene konverzije, što dovodi do smanjenja raspoloživih asimilata i formiranja ukupne biomase i prinosa zrna. Raspoloživi asimilati imaju ključnu ulogu u formiranju sve tri komponente prinosa; broja klasova po jedinici površine, broja zrna po klasu i mase zrna. Stvaranje genotipova tolerantnih na stres i primena odgovarajuće tehnologije proizvodnje predstavlja osnovne načine suprotstavljanja stresu. U radu je dat prikaz fiziološke osnove procesa koji određuju prinos ječma i uticaj činilaca stresa, posebno deficita vode, na biološki i ekonomski prinos ječma. .