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Thai indigenous rice varieties provide valuable genetic resources due to their environmental resilience, but it is yet to be elucidated whether their endosperm starches are suitable for whole grain consumption or industrial applications. Here, 19 Thai indigenous rice starches were explored for compositional, structural, and physicochemical characteristics. Grain reducing sugar, protein, and amylose contents significantly differed among genotypes. Their starches were categorized as waxy, very low-, and low-amylose starches. The varieties with low-amylose starches displayed higher amylose content but lower crystallinity than the varieties with waxy and very low-amylose starches. The largest median starch granule size (d(0.5)) was also observed in most varieties with low-amylose starches. The starch compositional and structural variations contributed to substantial differences in starch physicochemical properties among these genotypes. The partial least squares discriminant analysis revealed that amylose content, setback, swelling power, reducing sugar, C- and A-type granules, d(0.5), and final viscosity could discriminate the low-amylose starches from the waxy and very low-amylose starches. Notably, correlation analyses revealed that amylose content was the most crucial factor determining starch physicochemical properties of these varieties. Starch compositional, structural, and physicochemical variations among the indigenous rice varieties can be adopted as alternative industrial raw materials and as genetic resources for future breeding programs. [ABSTRACT FROM AUTHOR]

The sugar supplied by rice and the demand by N. lugens can affect the proportion of brachypterous forms in a population. Experiments were conducted to estimate the food ingestion by N. lugens per capita, to determine total food demand in a rice field, and to find the relation of food supply to the proportion of the brachypterous form. The results revealed that the sucrose content tended to decrease with the age of rice. However, the food demand by the N. lugens population dramatically increased in 40–89-day-old rice. The proportion of sugar supply to insect demand decreased as the insect population increased. The relative abundance of short-wing form insects increased when the ratio of sugar supply to insect demand was ≥0.02, but was decreased when the ratio was lower than 0.01. These results are useful for predicting N. lugens dispersal related to sugar supply in rice fields. [ABSTRACT FROM AUTHOR]

This study comprised collecting and determining the morphology and anatomy of leaf blade and leaf sheath of indigenous rice landraces in Khon Kaen, Thailand. A total of twenty-seven indigenous rice landraces were discovered, while, only 12-plant and grain samples were collected: Khao Plong Aew, Khao Jao Leuang, Khao San Pla Tong, Khao Gam Poon, Khao E-Leuang Noi, Khao Niaw dang, Khao Lao Taek, Khao E-Tom Kao, Khao Kam Pai, Khao Kao Gon, Khao Nang Nuan and Khao Mun Ped. Gross morphology was investigated and descriptions made. The anatomical characteristics of leaf blade and leaf sheath were studied using peeling and paraffin methods. The results demonstrated that the morphological and anatomical characters of 12 indigenous rice landraces are similar with a slight difference in some characters. Morphology differed in the color of collar, auricle and ligule as well as the shape and color of brown rice. The main distinguishing morphological characteristics for identifying indigenous rice landraces are grain features. For the anatomy of leaf blade and leaf sheath, the results revealed that there were only differences in the presence of prickles and the shape of anticlinal wall of epidermal cell on the lower surface of leaf sheath. Even thought, the anatomical characters of leaf blade and leaf sheath were not appropriated to identify the indigenous rice landraces in Khon Kaen. However, Khao Jao Leuang was distinguished from other indigenous rice landraces by the absence of prickles on both leaf blade surfaces. Moreover, Khao Jao Leuang is the only landrace in which the shape of the anticlinal wall of the epidermal cell on lower surface of leaf sheath, is undulate, others are sinuate. [ABSTRACT FROM AUTHOR]

Heat and high light intensity affected physiology and morphology of young Dipterocarpus alatus Roxb. leaf studied. D. alatus is a native forest tree and being extended to cultivation in the field as an economic crop. Nowadays, climate change due to increasing in temperature and light intensity can affect growth, morphological and photosynthetic traits in D. alatus. This research aimed to study the effects of high temperature and strong light intensity on physiology and morphology of the young D. alatus. The experiment was decided in CRD with 5 replications. The two-year-old D. alatus was treated with combination stress between temperature (at 35oC or 41oC) and light intensity (at 700 or 1800 µmol m-2s-1) for 7 days. Plant morphology, gas exchange, PSII efficiency and photosynthetic pigment contents were measured. Strong light intensity (1800 µmol m-²s-?) affected plant morphology by leaf burning and heat injury. However, high temperature (41oC) combined with strong irradiation enlarged leaf injury and also increased percentage of heat injury (3.01±0.81%; T41L1800) compared to control (0.07±0.00%; T35L700). In contrast, it reduced percentages of leaf angle (-8.77±2.82%) and leaf area (-1.04±0.38%). In addition, the combination stress influenced reduction of net photosynthetic rate and contents of Chl a+b and Chl a but unaffected Chl b and Car contents. Therefore, combined stress affected young D. alatus by damaging. [ABSTRACT FROM AUTHOR]

The effect of drought stress on leaf physiology was studied in 10-month-old plants of Sindora siamensis . Plants were either placed in an open greenhouse (unhardening; UH) or in an open field (open field hardening; H) for 45days. Both the UH and H plants stopped receiving water (D) until the initial drought injury and then rewatered (R) until complete recovery. Results showed necrosis in the leaves of UH+D, while H+D showed wilting at Day 7 after drought. A greater degree of necrosis was found in UH+D+R but made complete recovery in H+D+R at Day 4 after rewatering. Drought stress resulted in decreased leaf area in H, and reduced leaf and stem water status, PSII efficiency, net photosynthetic rate, stomatal conductance and transpiration rate in both UH and H. It also resulted in an increase in water use efficiency in both UH and H. Electrolyte leakage and malondialdehyde contents in UH were markedly increased due to drought stress. These results suggest that unhardened young plants of Sindora exposed to drought exhibited enhanced stomata behaviour by minimising open stomata and transpiration, resulting in high efficiency of water usage. However, there was still membrane damage from lipid peroxidation, which caused necrosis. Open field hardened plants exposed to drought demonstrated reduced open stomata and transpiration, thereby preserving leaf and soil water status and enhancing water use efficiency. This may be a reduction in lipid peroxidation though an oxidative scavenging mechanism that causes a slight alteration in membrane stability and a slight necrosis.