KAJIAN KARAKTER FISIOLOGIS VARIETAS PADI SAWAH PADA BUDIDAYA SECARA ORGAN

The reality in the field shows that not all lowland rice varieties which include local varieties, old superior varieties, new superior varieties and new types of varieties are suitable for organic cultivation because each group of varieties has different physiological characters. This research was carried out with the aim of determining the suitable lowland rice varieties for organic cultivation based on physiological characters. The research was carried out through pot experiments to determine the suitability of lowland rice varieties including local varieties, old varieties, new varieties, and new types of superior varieties in organic cultivation based on their physiological characteristics. with an altitude of 113 m above sea level with inceptisol soil types and tropical climate. The results showed that organic cultivation did not reduce root permeability to N uptake except for Cisedane variety. Organic cultivation lowered the KPK for the roots of the IR64, Cianjur and Mentikwangi varieties, but increased the KPK for the roots of the Pandanwangi and Cisedane varieties. The uptake rate of N, P, and K roots in organic cultivation was not different from conventional cultivation. The uptake of N roots in organic cultivation was lower than conventional cultivation. The uptake of N, P, and K by roots between varieties was not different. Organic cultivation reduced the uptake of N stems of varieties IR64, Mentikwangi and Cisedane. Among the varieties tested, there was no difference in N uptake in conventional or organic cultivation. Organic cultivation reduced the P uptake of stems of IR64 and Mentikwangi varieties, Organic cultivation decreased total N uptake of Mentikwangi varieties. In conventional and organic cultivation, the plant N uptake of all tested rice varieties was no different.

VviMYB41 orthologs contribute to the water deficit induced suberization of grapevine fine roots

ABSTRACTThe permeability of roots to water and nutrients is controlled through a variety of mechanisms and one of the most conspicuous is the presence of structures such as the Casparian strips and suberin lamellae. Roots actively regulate the creation of these structures developmentally, along the length of the root, and in response to the environment, including abiotic stresses such as drought. In the current study, we characterized the suberin composition along the length of grapevine fine roots during development and in response to water deficit. In parallel samples we quantified changes in expression of suberin biosynthesis- and deposition-related gene families (via RNAseq) allowing the identification of drought-responsive suberin-related genes. Grapevine suberin composition did not differ between primary and lateral roots, and was similar to that of other species. Under water deficit there was a global upregulation of suberin biosynthesis which resulted in an increase of suberin specific monomers, but without changes in their relative abundances, and this upregulation took place across all the developmental stages of fine roots. These changes corresponded to the upregulation of numerous suberin biosynthesis- and deposition-related genes which included orthologs of the previously characterized AtMYB41 transcriptional factor. Functional validation of two grapevine MYB41 orthologs, VviMYB41 and VviMYB41-like, confirmed their ability to globally upregulate suberin biosynthesis and deposition. This study provides a detailed characterization of the developmental and water deficit induced suberization of grapevine fine roots and identifies important orthologs responsible for suberin biosynthesis, deposition, and its regulation in grape.One sentence summaryOur study details the biochemical changes and molecular regulation of how grapevines decrease their root permeability during drought.

The barrier function of plant roots: biological bases for selective uptake and avoidance of soil compounds

The root is the main organ through which water and mineral nutrients enter the plant organism. In addition, root fulfils several other functions. Here, we propose that the root also performs the barrier function, which is essential not only for plant survival but for plant acclimation and adaptation to a constantly changing and heterogeneous soil environment. This function is related to selective uptake and avoidance of some soil compounds at the whole plant level. We review the toolkit of morpho-anatomical, structural, and other components that support this view. The components of the root structure involved in selectivity, permeability or barrier at a cellular, tissue, and organ level and their properties are discussed. In consideration of the arguments supporting barrier function of plant roots, evolutionary aspects of this function are also reviewed. Additionally, natural variation in selective root permeability is discussed which suggests that the barrier function is constantly evolving and is subject of natural selection.

Measurements of maize root plasticity under water stress in hydroponic chambers

1.AbstractUnder water stress, plants adjust root traits including depth of root system, root diameter, density of root per volume of soil, hydraulic conductance of root. In this experimental study, we present a method to quantify how hydraulic traits of maize roots adapt to drought. The experiments involve a microfluidic flow sensor and a custom-built pressure chamber, made of transparent plastic for visualization purposes. We measured how maize genotypes (PHB47 and PHZ51) grown for a week in deionized (DI) water and one day in hydroponic nutrients solution (called the irrigated condition) respond to one week of water stress. Conditions of water stress (called drought conditions) were created by mixing Polyethylene Glycol with the nutrients solution. Results show that under drought, the roots of both genotypes respond by approximately halving their global hydraulic conductance. This adjustment seems to be achieved mainly by reductions of the total surface area of the roots. Interestingly, the measured hydraulic conductivity of the roots grown under drought was significantly larger. In all, this study sheds light on how plants adapt to water stress in a hydroponic system, by decreasing root area and increasing root permeability.

Gas Exchange and Vine Water Relations are Crop Load Dependent

The effect of shoot density and crop level on gas exchange and water relations of filed-grown Sauvignon blanc was studied. Ten and 44 shoots/vine and one and two clusters per shoot treatments were examined in a factorial design. The two-cluster treatments had higher stem water potential (Ystem), assimilation rate, and stomatal (gs) and nonstomatal (gm) conductance. A quantitative analysis suggests that capacitance cannot account for the simultaneous increase in gs and Ystem in the two clusters treatment. The two-cluster treatment had higher Ystem for similar transpiration rates (similar gs) compared to the one-cluster treatment. The similar transpiration rate and lower stem to root water potential difference in the two-cluster treatment was explained by increased root permeability in the two-cluster treatment. The similar gs–gm, in spite of a meaningful decrease of gs with decreasing Ystem, suggests that gs and gm synchronize themselves to perturbations of gm due to sink effect and gs due to water stress.