Adaptation and performance of rice genotypes in tropical and subtropical environments

Abstract

a b s t r a c tStandardized field experiments were carried out to study the performance of five rice genotypes derived from different germplasm in terms of yield, harvest index (HI) and grain quality at eight agro-ecological sites of the tropics and subtropics across Asia during 2001 and 2002. Considering that indica and javanica genotypes adapt to warm climatic conditions, and japonica genotypes to cool agro-climatic conditions, it is hypothesized that indica × japonica hybrids may combine high yields and good quality traits under a wide range of agro-climatic conditions. Grain yield, HI, protein content and amylose content varied considerably among genotypes and environments. Mean rice yields of genotypes ranged from 1.5 to 11 t ha −1 across the eight sites; on average yields were 7.2 t ha −1 under subtropical and 2.7 t ha −1 under tropical conditions. The much lower yields in tropical environments resulted from a low biomass as well as a low HI. Among the genotypes, the indica × japonica hybrid showed the highest yield under subtropical conditions, and a higher yield than the japonica genotypes and the indica × javanica hybrid but lower than the indica genotype under tropical conditions. Phenology of genotypes varied strongly across environments. Low yields at tropical locations were associated with a low light capture due to short growth duration. Post-anthesis light-use efficiencies and the photothermal quotient explained much of the variation in yield. Protein content varied among genotypes depending on location and year. Variation in amylose content of rice grains was mainly associated with genotypic differences and much less with environmental conditions, but contents decreased with higher post-anthesis ambient temperatures. The indica × japonica hybrid combined high yields with a favourable amylose content and showed a better ability to adapt to cool and to warm agro-climatic conditions than the indica or japonica genotypes. Our study showed the magnitude of yield penalties associated with growing rice genotypes in environments to which they are not adapted. The consequences of these findings for improved adaptation of rice are discussed.

Impact of volunteer rice infestation on yield and grain quality of rice

“…Further, the segregating volunteer plants compete with the planted cultivar, but have variable yield potential and grain quality per se . Similar scenarios will ensue in fields infested with volunteers from inbred cultivars that differ in plant stature, maturity period, grain size and grain quality from the planted cultivar . The overall crop productivity is therefore reduced by having volunteers (which are less productive) in the mix, and the grain quality is compromised by contamination with different grain types and grains of different moisture contents owing to non‐uniform maturity of volunteer plants.…”

“…Likewise, volunteer rice grain can vary in protein content, which influences the physical and chemical properties of cooked rice . Protein content in general is influenced largely by environmental conditions, the level of available nitrogen and genotype . Amylose is one of the major components of starch .…”

“…13,14 Protein content in general is influenced largely by environmental conditions, the level of available nitrogen 15,16 and genotype. 17 Amylose is one of the major components of starch. 18 Amylose content is responsible for the stickiness and tenderness of cooked rice.…”

“…27,28 Similar scenarios will ensue in fields infested with volunteers from inbred cultivars that differ in plant stature, maturity period, grain size and grain quality from the planted cultivar. 4,6,17 The overall crop productivity is therefore reduced by having volunteers (which are less productive) in the mix, and the grain quality is compromised by contamination with different grain types and grains of different moisture contents owing to non-uniform maturity of volunteer plants. The potential economic impact of volunteer rice on the rice industry as a result of crop yield losses from competition and reduction in grain quality is not known.…”

Lipid Accumulation by Flavodon flavus ATH using Palm Oil Mill Effluent as Substrate

“…As awareness on the limited stock of fossil fuel and concern on environmental hazard of petroleum fuel is growing, research on sustainable biofuel is gaining its popularity (Richana 2010;Fujita 2004;Wraight & Ramos 2005;Jing 2010;Mohammadi 2011). Microbial based biofuel (micro-diesel) has become more attractive due to its environmental incentive and renewable properties (Zheng et al et al et al et al 2012).…”