The process of cell elongation from the viewpoint of plant-water relations and the effect of excision in the zone of elongation on changes in the water status are discussed. The excision effect on changes in water potential was evaluated after measuring turgor before excision and after excision in growing tulip tepals, and it was found that the size of wall relaxation was about 0.04 MPa. In mature tissues, there is no wall relaxation due to excision, and thus, the water status can be cross-checked by using a pressure chamber, a pressure probe and psychrometers. It was found that water potential of the apoplast is equal to the sum of the matric potential and the osmotic potential of the apoplast solution in the mature tissue. The symplast water potentials of epidermal cells and mesophyll cells were measured with the cell pressure probe, having the same values of water potentials measured with the psychrometer. Volume-averaged cell turgor and osmotic potentials were similar to the corresponding values measured in tissues with the psychrometer. In elongating tissues and mature tissues, it was confirmed that water potential can be expressed as the sum of pressure potential and osmotic potential in both the apoplast and symplast.
The growth parameters of Lockhart's equation were investigated for finding which component was predominantly contributing to the cell expansion rates of plants subjected to environmental stresses under tissue-culture conditions. Embryos isolated from soybean seeds were grown under tissue-culture conditions. The sizes of the water potential gradient between the water source and elongating cells correlated with the speed of growth rates under nutrient deficiency, salt stress, growth retardation induced by plant growth regulators and trehalose, indicating that cell expansion rates were mainly associated with how much water could be absorbed by elongating cells regardless of the kinds of environmental stress conditions applied.
Transpiration streams are induced by evaporative demand from the environment and distribute water solution from roots to tissues and cells in the respective organs through the complicated pathways. In these processes, physiological functions of plants such as stomatal movement, photosynthesis, phloem and xylem transport, nutrient uptake and expansive growth are affected by transpiration streams. Therefore, many kinds of techniques for measuring evaporative demand and transpiration streams in leaf boundary layer, leaves, fruits, stem, roots and plant canopy have been developed. The information about transpiration streams provided by the developed techniques must be more informative with cooperative measurements of plant physiological functions and must be more effective for the speaking plant approach to the environment control.
Early detection of water stress in tomato plants is required for the precise irrigation control to produce high-brix tomato fruits. For this purpose, we have developed a new water stress detection technique based on the projected plant area calculated from digital color images captured by a commercially available, inexpensive, digital still camera. As a first step, the effectiveness of using the projected plant area of tomato plants as a water stress index was confirmed by measuring the projected plant area along with other plant physiological information, e.g. leaf temperature, water potential, transpiration rate, and photosynthetic rate. Next, an image processing algorithm for the automated calculation of the projected plant area from digital color images was established using the discriminant analysis method. Furthermore, the most effective measurement angle of the projected plant area for the early detection of water stress was examined and measurement at an angle of 90° was proved to be the most sensitive to water stress in the tomato plant, i.e. wilting. The features of this technique are the stability of the projected plant area as an index of water stress, the low cost of the measurement equipment, and easy installation of the system. These features suggest that this technique can be introduced to commercial greenhouses to detect water stress in tomato plants and to be used for irrigation control for the production of high-brix tomatoes.
Continuous measurement of the growth of a storage organ is often required for analyzing environmental effects on crop production. Various techniques have been used for measuring storage organ growth. Non-contact methods are desirable for the growth analysis of an intact storage organ. Recently, laser beam-based measuring devices have been widely utilized in the industry for non-contact measurements of the width, length, or thickness of an object. These devices can also be effective tools for evaluating storage organ growth in plants. This article presents successful examples of the use of laser beam-based devices for non-contact growth measurements of two different types of storage organs, i.e., a tomato fruit and a sweetpotato tuberous root.
Approach on the environmental improvement has been done in a variety of industrial fields to correspond to serious global environmental concerns. The importance of the conversion to sustainable agriculture has been recognized in agriculture, and the technique breaking away from the agriculture depending on agricultural chemicals has been studied. In agricultural production in greenhouses, the production technique which does not use agricultural chemicals as much as possible attracted attention. The technique for plant height control using the temperature difference between day and night (DIF), which was developed in the 1980s and has been studied, is one of the alternatives of agricultural chemicals, and it has been widely used in the flower production in the world. This review is to summarize recent research results on DIF.
Bovine seminal plasma was submitted to chromatography on Con A-Sepharose. The “non-interacting”, “weakly-interacting” and “strongly-interacting” fractions were analyzed through UV-MALDI-TOF MS together with a subfraction of the “non-interacting” material, using sinapinic acid (SA) as matrix. The spectra were obtained in linear positive mode in the 4.0-90.0 kDa mass/charge range showing peaks in well defined zones, namely: 5.5-8.0 kDa, 10.0-12.0 kDa, 12.5-14.0 kDa (major), 23.2-23.7 kDa, 26.1-27.5 kDa and 38.0-40.0 kDa. High sensitivity spectra showed some very small peaks until 90 kDa. Bovine seminal protein (BSP-A3), acidic seminal fluid protein (αSFP) and PDC-109 glycoproteins (BSP-A1 and BSP-A2) were identified. Caltrin, the human epididymis-specific glycoprotein (HE4), the calcium transport inhibitor protein, the inhibitor of metalloprotease 2 (TIMP-2), osteopontin (OPN) and the prostatic acid protease (PAP) were tentatively identified. The molecular weight of some peaks can be arranged in a sequence from that of BSP-A3 going through the molecular weights of glycoforms (including the known BSP-A1 and BSP-A2) which differ in the amounts of neutral hexoses and sialic acids, composing a BSP-family more extended than previously reported. Another two families could be builded up from proteins of molecular weight of about 12730 and 12750 Da and glycoforms which differ from them also by hexoses and sialic acids. The structures of the deduced O-linked oligosaccharides of the glycoforms are in complete agreement to that determined for the BSP-A1 oligosaccharide. Small differences in the m. w. of some (glyco)proteins were attributed to genetic polymorphysm. The identification of proteins and O-linked glycoproteins in the “interacting” fractions of the chromatography suggests that the fractionation was not due to specific affinity interactions but to non-specific hydrophobic interactions of the proteins with the hydrophobic pocked of the Con A.