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The development of self-oxidative defense is a crucial mechanism of crops to survive in an unfavorable condition such as drought and salinity. The possible involvement of the antioxidant gene(s) in such defense under drought and salinity stresses was studied in leaves of rice (Oryza sativa L.) Cv Cempo Ireng seedling. Fifteen days old seedlings were subjected to 0.2 (extreme), 0.5 (mild) and 1.0 (control) FTSW (fraction of transpirable soil water as representative to drought stress) levels, and 0 mM (control) 125 mM (mild) and 250 mM (extreme) NaCl as representative to salinity stress levels for 6 d. The transcription levels of cCuZnSod1, cCuZnSod2, MnSod1, cApx1, cApx2, chl-tApx, Cat1, Cat2, Cat3, Gr1, Gr2 and Gr3 were analyzed using semi-quantitative RT-PCR technique. The antioxidant genes in seedling treated to drought showed a difference of transcription levels to seedling treated to salinity. The number of antioxidant genes increasing in transcription was lower in rice seedling under drought (cCuZnSod1, cCuZnSod2, cApx2, cApx3, Cat1, Cat2, Gr2 and Gr3) as compared to that in seedling under salinity (cCuZnSod1, cCuZnSod2, MnSod1, cApx2, cApx3, Cat2, Cat3, Gr1, Gr2 and Gr3 ). The present concluded that dismutation of superdioxide radical and biosynthesis of reduced ascorbic acid in gluthationine-ascorbate cycle within cells were less in seedling under drought stress so that the oxidative damage of seedling under drought was higher than that under salinity. [ABSTRACT FROM AUTHOR]

The roles of quantitative physiology are becoming more apparent and crucial in the era of ICT recently. As based on the rate-related variables, most of the mathematical models are in the form of ‘non-linear’ function in describing the responses or the observed within-plant processes outcomes versus time. Even though if some responses change in a drastic manner at certain response point within a biological unit or space of a plant system, the response curve ‘should’ be dependent on a continuous independent variable range in a specified period of determination where biologically ‘should not’ functioned by independent variable range having ‘IF’ statement(s). Subjected to nutrient concentration of high salinity (6.0 mS cm-1), the leaf turgidity (measured as leaf surface area) of S. arboricola which initially was described by one form of the logistic growth functions [(y = 1/(a+be-cx)] abruptly reduced as explained by a model having terms of Absolute function (ABS) containing tan-1(x) and its parameter of leaf life expectancy as affected by high salinity growing medium at a certain point of days after planting. This yielded an overall function of y = 1/(a+be-cx)-A[tan-1{(x-B)/D}+ABS(tan-1{(x-B)/D})]E, where a, b, c, A, B, D, and E are constants that most of them can be ‘biologically’ interpreted. The constant B is the point similar to ‘IF statement’ as normally used in other mathematical functions. Plants subjected to lower salinity status (<3.0 mS cm-1) were only having function of y = 1/(a+be-cx). In the harvest index or HI (economic yield/above ground biomass) study of 20 rice varieties grown over two planting seasons, the long flattened tails at both sides of a peak in the middle of function of y = R+B(T+ABS(B-x))e-k(T+ABS(B-x)) had indicated that those varieties maturing at 123 to 133 days after transplanting were having high HI values. In our observation, Absolute (ABS) function coupled with some terms could be used in the formation of some mathematical functions having biological meaningful constants in explaining some quantitative physiological and biological responses vs. independent variables studied. [ABSTRACT FROM AUTHOR]