Distribution of Na+ along the root axis under salinity stress was analyzed in two rice (Oryza sativa L.) cultivars with different salt resistance (salt-sensitive IR 24 and salt-resistant Pokkali). Rice plants were grown hydroponically and NaCl was applied with nutrient solution at concentrations of 0, 25 and 50 mM for 7 d after germination. The distribution of Na+ in roots under salinity was analyzed by the cryo time-of-flight secondary ion mass spectrometry (cryo TOF-SIMS). The Na+ content in the root was higher in salt-sensitive IR 24 than in salt-resistant Pokkali under NaCl stress. The content was highest at the root tip and was decreased basipetally along the root axis. The difference in Na+ content between the cultivars was apparent in all regions from the root tip.
Localization of storage proteins in rice grains of seed-protein mutant cultivars, low-glutelin cultivars LGC-1, LGCsoft and a 26-kDa-globulin-deficient low-glutelin cultivar LGC-Katsu, was examined by immunofluorescence microscopy using fluorescence-labeled antibodies of 13 kDa prolamin and 23 kDa glutelin. Abundant 13 kDa prolamin and 23 kDa glutelin was observed in the outer regions of rice grains. Image analysis revealed that peaks of fluorescence intensity of both proteins were located at 2–7% of the width or longitudinal length of brown rice distant from the outer surface of brown rice (RDOS) on the dorsal, ventral, and apical sides of brown rice. In these seed-protein mutant cultivars and a normal-type cultivar Nihonmasari, the foot of the distribution peaks of both proteins were located at 20–30% RDOS on the ventral and apical side. In contrast, on the dorsal side of rice grain, varietal differences of RDOS at the foot of the distribution peak of both proteins varied with the cultivar. The RDOS was 20–40%; and Nihonmasari>LGC-1≒LGCsoft>LGC-Katsu. Although the quantity of 13 kDa prolamin and 23 kDa glutelin greatly varied with the cultivar in the outer region of rice grain, both proteins were distributed uniformly at low levels in the inner region in all cultivars. Furthermore, SDS-PAGE analysis showed that a larger quantity of 13 kDa prolamin localized on the ventral than the dorsal side of rice grains in seed-protein mutant cultivars, especially in LGC-Katsu.
The conventional system of sugarcane (Saccharum species complex) planting is inefficient for rapidly multiplying the seed cane of newly released varieties due to a higher seed rate (6.0 t ha-1) and low germination rate (35−40%). We examined the effect of planting methods on the multiplication rate of seed cane in a field experiment conducted at Lucknow (India) during the 2005−06 and 2006−07 cropping season. Forty- day- old plantlets grown in polythene bags in the nursery using 28,000 single-bud cane pieces per ha area, were transplanted at 45 cm spacing in furrows 90 cm apart and the results were compared with those obtained by the conventional practice of planting three- two - and one- bud cane pieces at the rate of 37,000, 55,500 and 111,000 setts per ha, respectively. The polythene bag culture produced a significantly higher number of shoots and millable canes and a higher seed cane yield as compared with the conventional planting method, which is an advantage for seed cane multiplication. The results further indicated that with almost equal cost of cultivation, the rate of seed cane multiplication was about 35 times by the polythene bag culture method and 8−11 times by the conventional planting method.
Sunflower, a major edible oil crop producing a high-quality and healthful oil for human consumption and also recycled for use as feedstock to produce biodiesel fuel, is recently being cultivated in rotation with rice in the paddy field. The oil of cultivars with a high oleic acid content has higher oxidation stability and better nutritional properties than the standard cultivars, which have a high linoleic acid content. In this study, we evaluated the effects of excess water on plant growth, seed yield, and oil quality. Seed yield, the major yield components, the oleic acid content and the total oil content were negatively affected by a shallow water table. In particular, waterlogging at the establishment stage decreased the growth and seed yield severely. In addition, waterlogging during the flowering and maturation stages tended to decrease the oleic acid content and to increase the linoleic acid content. These results will be useful for improving management practices to increase the seed yield and improve the oil quality of sunflower in rotation with upland paddy rice.
NH3 emission from leaves of three rice (Oryza sativa L.) cultivars, Akenohoshi, Shirobeniya and Kasalath, was examined using a simple open chamber system. In the three cultivars, NH3 emission rate (AER) and NH4+ content of leaves decreased with decreasing NH4+ concentration in the root medium, but these values differed significantly with the cultivar. In the daytime, AER, NH4+ content and glutamine synthetase (GS) activity in leaves changed similarly with maximum values around midday. Akenohoshi showed significantly lower AER and NH4+ content but higher GS activity than Kasalath. The difference in AER among the rice cultivars may be related to the activity of GS involved in photorespiratory NH3 recycling. Akenohoshi can be a breeding material useful for improving N recycling.
We investigated responses of wet climate (CY17) and dry climate (XN889) Trititcum aestivum L cultivars under 85, 55 and 25% field water capacity (FC). Less decrease in grain yield, relative water content, growth, gas exchange and chlorophyll fluorescence parameters indicated that XN889 was more drought-tolerant than CY17. At 55%FC, CY17 showed a lower net photosynthetic rate (Pn) than XN889 mainly due to stomatal closure. Stomatal closure was also observed in XN889, but its Pn was higher at 55%FC than at 85%FC. The higher Pn in XN889 may be associated with a higher chlorophyll content and resulting increase in photochemical quenching (qP), apparent electron transport rate, and effective quantum yield of photosystem II (PSII). Both cultivars showed photodamage at 25%FC, but XN889 showed less photodamage in terms of maximal PSII photochemical efficiency. XN889 showed higher qP and non-photochemical quenching than CY17, further demonstrating its superior drought tolerance.
We grew 1005 mutated scented japonica rice lines to the seventh steady genetic generation, and treated the seedlings with six true leaves with 300 mM NaCl for three days. Only the salt-tolerant line, SM61, survived. We obtained F1, F2 and F3 populations from the cross between SM61 and a salt-susceptible indica variety, TCS17. After culture with 200 mM NaCl for five days, SM61 and F1 (SM61×TCS17; TCS17×SM61) plants survived (R) while TCS17 plants did not (S). The R to S ratio in 513 F2 plants showed a good fit to the Mendelian 3 : 1 segregation ratio by a Chi-square test indicating that the salt-tolerance of SM61 was governed by a single dominant gene. The mutated salt-tolerance gene explained close to 100% of the total phenotypic variation, and was tightly linked to RM223 (marker) located on chromosome 8, which was different from the results of previous studies investigating the relationship of QTLs with salt tolerance. This is the first report of mapping tightly linked markers of a single dominant mutated salt-tolerance gene.
To realize non-destructive and real-time monitoring of crop nitrogen status for precision management in rice fertilization, we characterized the reflectance spectra in the red edge area from ground- and space-based data, and quantified the relationships between the red edge position (REP) derived from different algorithms and canopy leaf nitrogen concentrations (LNC) at various nitrogen rates in four seasons in various cultivars of field-grown rice (Oryza sativa L.). The results showed that the spectrum in the red edge area was significantly affected by the nitrogen level and cultivar type, and “three-peak” feature could be observed in the first derivative spectrum in this area. Traditional REP (maximum value of the first derivative spectra in red-edge region) was not sensitive to canopy LNC because of the three-peak property, but the REPs based on inverted Gaussian fitting, linear four-point interpolation, linear extrapolation and adjusted linear extrapolation generated continuous REP values, and could be used for estimating canopy LNC. REP from a three-point Lagrangian interpolation with three first-derivative bands (690 nm, 700 nm and 705 nm) had a good relationship with canopy LNC. Among the six REP approaches, REP based on adjusted linear extrapolation algorithm was found to have the best relations with canopy LNCs in Hyperion image data. Comparison of the different REPs with both ground-based and space-borne hyperspectral data indicated that the adjusted linear extrapolation method (755FD730+675FD700)/(FD730+FD700) proposed here gave the best prediction of canopy LNC. This simple and reliable REP approach to monitoring canopy LNC in rice requires further verification with other hyperspectral sensors and crop types.
Formation of chalky grains which is the main cause of the degradation of rice grain quality occurs frequently when the temperature during the 20 days after heading exceeds 27ºC. In this study, we examined the grain quality, chalky grain formation, growth and yield of plants grown by the deep and permanent irrigation (DPI) method, which is a combination of the V-furrow direct seeding method and the deep-flooding irrigation method. Field experiments were conducted in 2008, 2009 and 2010. The DPI method in which the water level was maintained at about 20 cm above the soil surface, improved grain quality by decreasing the chalky grain ratio by about 5% and increasing the perfect grain ratio by about 10% as compared with the V-furrow direct seeding method in which the water level was maintained at about 10 cm above the soil surface. The DPI method decreased the number of tillers and panicles but increased the number of spikelets per panicle so that the two methods gave similar yields. DPI is a promising labor-saving method expected to reduce the formation of chalky grain due to a high temperature during ripening.
Seed tubers of sweet potato cultivar “Murasakimasari”, the weights of which range from 30 to 100 g, were cut in half at a right angle to the long axis of the tuber, and planted in cell trays (cell size: 55 mm×55 mm×height 62.5 mm, 50 cells in a 30 cm×60 cm tray) with commercial soil mixes. The planted half-cut tubers in cell trays were incubated at 25ºC under natural sunlight conditions in a glasshouse for 3 to 4 wk to raise half-cut tuber seedlings. Half-cut tuber seedlings were transplanted on 28 March (TST1) or on 24 April (TST2), whole seed tubers were directly planted on 26 March (DP), conventional sprouted vines were planted on 30 April (VP) in an experimental field. The highest tuber yield was obtained from TST1, followed by TST2 and VP, and DP in this order. Deformed tubers emerged from the TST1 and TST2 groups, at a rate of 3.0% and 6.7% of daughter tubers, respectively. A regional trial in a farmer's field revealed that the tuber yields and numbers of tubers per plant were higher in TST (tuber seedling transplanting) than those in VP (vine planting). The statistical analysis of the 2 field experiments suggests that transplantation of half-cut tuber seedlings provides enhanced yields over conventional sprouted-vine planting.