Chlorophyll a content in segments of flag leaves from 19 wheat varieties excised at ear emergence was shown to vary by a factor of 2.3. Chlorophyll stability (expressed as the percentage of chlorophyll remaining in the segments after 4 days senescence in moist boxes at 20 °C in the dark) varied by a factor of 8.5. Variation in these parameters between varieties appeared to be independent. Five of these varieties, representing the extremes, were further tested at three nutrient levels, and under three light/temperature regimes. Whilst lower leaf canopy senescence was greater at low nutrient levels, flag leaf chlorophyll content actually increased slightly, stability remaining fairly constant. In contrast, as light intensity improved, chlorophyll content increased markedly, with a consequent slight non-significant decrease in stability. Testing the F1 progeny of a partial diallel involving four of the above varieties showed that the mean chlorophyll content, and stability, of the parents followed the same ranking as the progeny to which they contributed. This suggests heritable control of the parameters measured. Some implications of these results in breeding for resistance to senescence are discussed.

Peas plants of the varieties Okaw and Asgrow 40 were cultivated incomplete nutrient solution. Periodically from 10 th day up to 90 days. Height (cm) dry wheigh matter (gr) of the plants were obtained at the different stage plants growing. Stalks, leaves husk+seeds, were analysed for N, P, K, Ca Mg, S, B, Cu, Fe, Mn, Zn and Mo. Conclusions: 1 - The variety Okaw presented a continous growth, expressed as "wet matter production" until the both day. For the variety Asgrow 40 the growth ceased around the 40th day; 2 - The capaty for nutrients extration were distinct between the varieties, for the variety Okaw around the 90th day for the variety Asgrow 40, around the 60th day; 3 - One ha of peas plants (kg/ha) removed the following quanties in nutrients kg. Extraction Exported Nutrient (stalks + leaves + flowers + "husk + seeds" (husk + seeds) Var. Okaw Var. Asgrow Var. Okaw Var. Asgrow 40 40 kg/ha kg/ha kg/ha kg/ha N 80 78 36 14 P 8 7.9 4.3 2.7 K 62 50 16 3 Ca 32 21 6 2 Mg 9.2 5.7 2.8 0.4 S 19 11 2 1 gr./ha gr./ha gr./ha gr./ha B 194 149 36 15 Cu 51 37 25 9 Fe 244 250 64 11 Mn 237 278 32 9 Mo 4.9 5.8 1.7 0.8 Zn 624 304 30 12 4 - the extraction of nutrients were similars in both varieties; 5 - the exportations of nutrients were higher in the variety Okaw, than in the variety Asgrow 40. | O presente trabalho teve o objetivo de estudar alguns aspectos da nutrição da ervilha, nas variedades Okaw e Asgrow 40 no que concerne a extração dos macro e micronutrientes durante o desenvolvimento das plantas. Sementes de ervilha de ambas variedades foram postas a germinação em silica. Uma vez germinados as plantulas foram irrigadas com solução nutritiva completa até ao final do ciclo. Periodicamente, de 10 em 10 dias até aos 90 dias plantas foram coletadas, mensuradas em altura, determinado o peso da matéria fresca e seca, analisadas para os macro e micronutrientes. A variedade Okaw apresentou um desenvolvimento e extração maior de nutrientes, do que a variedade Asgrow 40. A variedade Okaw apresenta maior exportação de nutriente.

Two snapbean (Phaseolus vulgaris L.) varieties, shown previously to differ in tolerance to acid, Al-toxic Bladen soil, were tested more specifically for Al tolerance in nutrient cultures. The Bladen soil-tolerant ‘Bade’ variety was much more tolerant to Al than Bladen-sensitive ‘Romano.’ For example, with 8 ppm Al added, at initial pH 4.8, top and root yields of Dade were 94 and 107%, respectively, of those with no Al. Corresponding top and root yields of Romano were only 53 and 59%, respectively, of those with no Al. With 8 ppm Al added, the total Ca uptake values for Dade tops and roots were 98 and 131%, respectively, of those with no Al; corresponding values for Romano tops and roots were only 25 and 22%, respectively. Aluminum added at 6 or 8 ppm also reduced Ca concentrations in tops and roots of Romano by 30 to 50%, but had little effect on those of Dade. Differential Al tolerance was not related to differential pH changes in nutrient solutions or to Al concentrations of plant tops or roots. With 8 ppm Al added the P concentrations in Romano tops and roots were 60 and 14% higher, respectively, than those of Dade. Aluminum added at 4 ppm decreased stem exudate production of Romano by 66% but did not affect that of Dade. The same Al treatment reduced concentrations of Ca, Mg, K, and P in Romano exudates by 66, 42, 80, and 76%, respectively, but either decreased or failed to affect those of Dade. Lower concentrations of these elements in stem exudates of Al-injured Romano plants were not associated with immobilization hi roots. The 4-ppm Al treatment decreased Ca concentrations in Romano root cell walls, mitochondria, supernatant, and total roots by 55, 68, 51, and 43%, respectively. The same treatment decreased the Ca concentration hi Dade root cell walls by only 27% and that in total roots by 8%, and actually increased the Ca concentration in mitochondria and supernatant fractions by 21 and 63%, respectively. Reduced Ca uptake appears to be a good indicator of Al sensitivity in the two snapbean varieties studied.

The presente work, was carried out in order to study: a) the effect of omission and presence of the macronutrients on the growth of the plants; b) the amounts of macronutrients, absorbed during the growth of the plants; c) the sensibility to nutritional deficiences. Young sweet pepper plants of varieties Avelar and Ikeda were grown in pots containing pure quartz. Twice a day, they were irrigated by percolation with nutrient solution. The treatments were: complete solution and deficient solutions, in which each one of the macronutrients was omitted (HOAGLAND & ARNON, 1950). When the malnutrition symptoms appeared, the plants were harvested and their dry matter was analysed chemically. The absorption of macronutrients was studied with the plants of both varieties, cultivated under field conditions. Periodically, plants were harvested and analysed for N, P, K, Ca, Mg and S. Conclusions: 1 - both of the varieties are resistent to blossom-end rot; 2 - the variety Avelar has a greater demand in macronutrients, on the begining of fruitage, than the variety Ikeda; 3 - the variety Avelar is more sensibile to deficiencies of the macronutrients, than the variety Ikeda; 4 - the initial rate of growth of the sweet pepper during the first 75 days, in rather slow; 5 - new experiments are necessary to study times of application of N; 6 - there's no significant difference between the varieties, in the total nutrients absorbed on the end of the plant cycle; 7 - one ha of sweet plants (31,250) remove and export the following quantities in nutrients: | O presente trabalho teve como objetivos, estudar comparativamente aspectos da nutrição mineral das variedades de pimentão, Avelar e Ikeda, no que concerne: a) ao efeito da omissão e presença dos macronutrientes, no crescimento das plantas; b) às quantidades de macronutrientes absorvidos durante o crescimento das plantas; c) à sensibilidade a deficiências minerais. Plantas de pimentão, das variedades Avelar e Ikeda foram cultivadas em vaso contendo silica. Aos sessenta dias de idade foram submetidas aos tratamentos, que constaram do cultivo de plantas em solução nutritiva completa e omitindo um macronutriente por vez. As mesmas variedades foram também cultivadas em condições de campo, coletando-se amostras de plantas periodicamente. Obtidos materiais de ambos os ensaios, processaram-se as análises químicas. A var. Avelar mostra-se mais exigente em nutrientes, no período inicial de frutificação e é mais sensível a carências nutricionais que a var. Ikeda.

Much has been written about how phosphate accentuates Fe deficiency in plants; but little attention has been given to the genotype of rootstock as a controlling factor in Fe uptake. The important role of the plant was studied in these experiments. Competition between phosphate, the plant, and ferrofine for Fe in nutrient solution was examined. Fe inefficient and Fe efficient varieties of soybeans [Glycine max (L.) Merr.] (Lycopersicon esculentum Mill.) were used as test plants because they differ, respectively, in their ability to tolerate P and to reduce Fe³⁺ to Fe²⁺ at the root. Within 2 days after adding 16 ppm of P to the nutrient solution, only about 10% of the Fe²⁺ferrozine was colorimetrically detected in solution. The Fe was removed from Fe²⁺ferrozine, and it appeared in the solution as a suspension of iron-phosphate. Phosphate was dominating the system for Fe. Four days later, the plants developed Fe deficiency (Fe stress). Fe-efficient plants responded to Fe stress by releasing more H⁺ into solution and reducing more Fe³⁺ to Fe²⁺ than was reduced by Fe-inefficient plants. As this occurred, Fe²⁺ferrozine reappeared in solution. The Fe-efficient plants now dominated the system for Fe. On day 17 (final harvest), the green top leaves of Fe-efficient HA soybeans contained 86 ppm of Fe, whereas the chlorotic top leaves of Fe-inefficient PI soybeans contained only 36 ppm Fe. In the latter, phosphate still dominated the system for Fe because the reducing capacity (Fe³⁺ to Fe²⁺) of the Fe-inefficient plants was not great enough to overcome the effects of phosphate.