| Abstracts on sustainable agriculture 1992 Gate- GTZ |
|Abstracts on soil fertility|
Tesis Universidad Nacional de Colombia, Bogota, Colombia; Ing. Agr. Palmira: 1991, 81 pp.
The influence of certain quantitative characteristics of bean seed on the capacity of seedlings to tolerate low available P in the soil was determined. The starch, protein, phytic acid, and different P fractions of the seed were determined in 23 bean genotypes during the 1th phase of research. Results indicated that the reduction in total biomass production of the seedling and in tissue P concentration was pronounced at 16 days after planting, as a direct consequence of soil P deficiency.
However, this reduction was more pronounced in the leaves since a greater amount of photosynthates were invested in root production, thus increasing the relative extension of the root system in the soil. The no. of main roots proved to be a variety characteristic that is unmodified by soil P levels. On the other hand, the size of endodermical cells was significantly increased by the low P treatment, possibly due to a nutritional physiological adaptation mechanism; however, no significant differences were found among variety. Seed weight and size of cotyledon cells showed a positive, highly significant correlation with seedling vigor. The coefficients of correlation obtained in the low P treatment were higher than those of the high P treatment, indicating that the nutritional dependence of the seedlings is more pronounced under P deficiency conditions. Variance analysis showed that cotyledon reserves satisfied the nutritional needs of the seedlings more less up to 12 days after planting, after which significant differences in growth rates occurred. Although total biomass production was directly related to seed size, it did not affect the duration of reserves. Although the experiments attempted to minimize the variations existing between environments (pots and tubes) and between replications, statistical analysis revealed significant differences due to these factors. Root analysis in modified PVC tubes was useful in the study of overall genotype performance, but maladjustments occurred that affected the final results of P treatment.
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Asia, India, field trial, legumes, arid areas, phosphate application, soil nitrogen, pearl millet
KATHJU, S. et al.