Estimation of Drought Tolerance Based on Leaf Temperature in Upland Rice Breeding

Abstract

The evaluation of drought tolerance based on the leaf temperature was examined in upland rice breeding. The relationships of the leaf temperature with the transpiration and photosynthetic rates were observed in upland and lowland rice varieties under upland cultivation in 1995, 1996 and 1997. The leaf temperature of the upland rice varieties was lower than that of the lowland rice varieties. Their transpiration and photosynthetic rates were highly correlated with the leaf temperature, measured using an infrared radiation thermometer or portable photosynthesis gas analyzing system in all the three years. The leaf temperature also showed a significant relationship with the grain yield tested in 1995. It is considered that rice varieties with a lower leaf temperature can maintain high transpiration and photosynthetic rates as well as produce a high yield under upland conditions. In addition, there was a significant positive correlation between the leaf temperature and root growth recorded by the trench method. Upland rice varieties with deep rooting showed lower leaf temperatures than those with a shallower root system. On the other hand, in the comparison of leaf temperature in varietal groups of breeding materials, the upland rice lines with medium-late maturity showed the lowest temperature, followed by the early maturing lines and lines for cultivation with sprinkler irrigation. This tendency was in agreement with the general degree of drought tolerance of individual varietal groups. To analyze the mode of inheritance of the leaf temperature, the parent-offspring correlation of leaf temperature measured using an infrared radiation thermometer was examined in breeding materials. Leaf temperature was compared between the progeny lines (F 4 generation) of the upland rice variety Kantomochi168 with a high drought tolerance and the upland rice variety Norinmochi4 with a medium drought tolerance. Kantomochi168 progeny showed a lower leaf temperature than Norinmochi4. A similar tendency was confirmed in the F 5 generation in the following year. Significant parental-offspring correlation (r = 0.812**) was observed between F 4 and F 5 . Since the leaf temperature of the upland rice progeny may display a relatively higher inheritance, the leaf temperature is, therefore, considered to be a useful indicator to estimate the drought tolerance for line selection in upland rice breeding.

PHYSIOLOGICAL RELATIONSHIPS IN Aleurites fordii Hemsl. SEEDLINGS

“…These justifications reported in the literature corroborate with the results found in this paper and those reported by Hirayama et al (2006), in which it was verified that LT was highly correlated with TR. In the same way, Table 1 shows a very high correlation between LT and TR (0.93).…”

Evapotranspiration and grain yield of upland rice as affected by water deficit

“…Plants exposed to water stress closed their stomata to maintain their inner moisture content and, consequently, their transpiration and photosynthetic rates, and productivity decreased (Hirayama et al, 2006). Parent et al (2010) found that under well-watered conditions, stomatal conductance of seven rice cultivars ranged from 0.21 to 0.30 mol m -2 s -1 and was reduced in all cultivars with soil water deficit (0.07-0.145 mol m -2 s -1 ).…”

Management of crop water under drought: a review

“…Mori et al (2011) used infrared thermography to analyse differences in root water uptake associated with a water-saving behaviour of wheat in a Mediterranean climate. Hirayama et al (2006) showed the strong negative correlation of leaf temperature with transpiration and photosynthesis in upland rice. Liu et al (2011) demonstrated the relation between leaf temperature and drought tolerance for maize.…”

“…The first process in the field water cycle is rainfall infiltration. Hillel (1980) gives five factors controlling infiltrability, i.e. time from the onset of rain, initial water content, soil hydraulic conductivity, soil surface conditions (porous vs. crusted) and impeding layers in the soil profile.…”

“…In supply-driven ecosystems, plant water supply depends on in-season rainfall, while crop performance in storagedriven systems is strongly linked to soil retention of rainwater fallen before the time of maximum crop demand 60 % of total evapotranspiration (Siddique et al 1990a;Debaeke and Aboudrare 2004). The amount of evaporation losses depends on climate (evaporative demand) and soil conditions (surface wetness, soil hydraulic conductivity ;Hillel 1980;Gregory et al 2000). Soil cover (crops, mulch) alter the radiation balance at the soil surface, thereby reducing evaporation.…”