Leaf Characteristics at Recovery Stage Affect Seed Oil and Protein Content Under the Interactive Effects of Nitrogen and Waterlogging in Rapeseed

Four nitrogen rates (0, 90, 180, and 270 kg ha−1) were applied to the waterlogging-tolerant variety ZS 9 and the sensitive variety GH01. Seedlings with five leaves were waterlogged for 0 (control) or 10 days to investigate the effects of nitrogen on the quality of waterlogged rapeseed. Compared with controls, the seed oil content of waterlogged rapeseed increased slightly in GH01 and significantly in ZS 9 with nitrogen application, which can be explained by the following. (1) after waterlogging, the biomass distribution in roots and leaves of ZS 9 decreased, which alleviated physiological water shortage. Conversely, biomass distribution in roots of GH01 increased, which was not synchronized with the leaf biomass change. (2) After waterlogging at 90–270 kg N ha−1, the leaf number at bolting and flowering was increased in ZS 9 but decreased in GH01 compared with the control. The decrease in leaf area and SPAD value were greater for GH01 after waterlogging, which limited photosynthesis. (3) The leaf soluble protein at bolting was highest in ZS 9 and lowest in GH01. The sensitive variety showed poor growth. The inhibition of seed protein synthesis resulted in an increase in the oil content of waterlogged rapeseed with nitrogen. The seed oil of the waterlogging-tolerant variety was most significantly negatively correlated with leaf soluble protein content at the flowering stage, while the protein content showed the opposite correlation. The seed oil of the waterlogging-sensitive variety was most significantly negatively correlated with the number of leaves at the bolting and flowering stage, while the seed protein content had opposite correlations.

Nitrate reductase and glutamine synthetase activity in coffee leaves during fruit development

Nitrate reductase is the first enzyme in the pathway of nitrate reduction by plants, followed by glutamine synthetase, which incorporates ammonia to glutamine. The purpose of this study was to evaluate the nitrate reductase and glutamine synthetase activity, total soluble protein content, N and Ni content in coffee leaves during fruit development under field conditions to establish new informations to help assess the N nutritional status and fertilizer management. The experimental design was in randomized complete blocks, arranged in a 3 x 6 factorial design, with five replications. The treatments consisted of 3 N rates (0 - control, 150 and 300 kg ha-1) and six evaluation periods (January, February, March, April, May, and June) in six-year-old coffee (Coffea arabica L.) plants of Catuaí Vermelho IAC 44 cv. The nitrate reductase and glutamine synthetase activities, leaf soluble protein, and N concentrations increased linearly with the N rates. During fruit development, the enzyme activity, leaf soluble protein and N content decreased, due to the leaf senescence process caused by nutrient mobilization to other organs, e.g, to the berries. Leaf Ni increased during fruit development. Beans and raisin-fruits of plants well-supplied with N had higher Ni contents. Enzyme activities, total leaf N and leaf soluble protein, evaluated during the green fruit stage in March, were significantly correlated with coffee yield. These variables can therefore be useful for an early assessment of the coffee N nutritional status as well as coffee yield and N fertilization management.

743 PB 073 ANATOMICAL AND PHYSIOLOGICAL DIFFERENCES AMONG THREE SPECIES OF Fragaria

Several anatomical and physiological parameters were measured in 32 genotypes of fragaia, including the cultivated strawberry (frapria × ananassa) and its progenitor speck F. chiloensis and F. virginiana Measurements were made using potted. runner-propagated, &month-old greenhouse-grown plants growing under long day (14/10) conditions. Significant differences in CO2 assimilation rates (leaf area and dry weight bases). leaf chlorophyll content, leaf soluble protein content, and leaf anatomy were found between subspecies of F. virginana as well as among species. Recessed stomata and greater water use efficiency were observed in F. virginana ssp glauca as well as in F. chiloensis genotypes. In addition, it appears that leaf anatomy characteristics, as studied using light microscopy, may he useful in corroborating taxonomic decisions based upon gross morphology in Fragaria.

High Root-zone Temperatures Influence RuBisCO Activity and Pigment Accumulation in Leaves of `Rotundifolia' Holly

Plants of `Rotundifolia' holly (Ilex crenata Thunb.) were grown for 3 weeks with root zones at 30,34,38, or 42C for 6 hours daily to evaluate the effects of supraoptimal root-zone temperatures on various photosynthetic processes. After 3 weeks, photosynthesis of plants grown with root zones at 38 or 42C was below that of plants grown at 30 or 34C. Chlorophyll and carotenoid levels decreased while leaf soluble protein levels increased as root-zone temperature increased. Ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) activity per unit protein and per unit chlorophyll responded quadratically, while RuBisCO activity per unit fresh weight increased linearly in response to increasing root-zone temperature. Results of this study suggest that `Rotundifolia' holly was capable of altering metabolism or redistributing available assimilates to maintain CO2 assimilation rates in response to increasing root-zone temperatures.