Influence of position of panicle on seed and seedling characteristics of rice (Oryza sativa L)

The characteristics of seeds obtained from primary, secondary and tertiary branches of panicles in four varieties. of Indica rice (Oryza sativa) were evaluated. The germination patterns and viability of procured seed and the vigour and characteristics of seedlings developed from these seeds were also studied. The characteristics of seeds of the three branch types ofthe four varieties and their seedlings were similar. In contrast, marked differences were observed between the seeds obtained from the three types of branches. Seeds of primary branches of the panicle had a greater 100-seed weight. The lowest weight was observed in seeds from tertiary branches. This difference was principally due to the heavier endosperm of the seeds of primary branches, which in turn increased the endosperm:embryo ratios. The viability and germinability ofthe three categories ofseed were similar to those ofseed characteristics. Seed from primary branches of the panicle had a higher viability. The vigour of seedlings from these seeds was also greater. Differences in growth of seedlings from the these seeds was also greater. Differences in growth ofseedlings from the three branches of the rice panicle were similar in terms of characteristics and viability of seeds. The study revealed that seedlings from seeds of primary branches manifested superior growth because of better seed characteristics. Some practical implications of the study are discussed

Response of selected tropical grasses to irrigation with brackish water

Agricultural development programmes in the sandy regions of the dry zone of Sri Lanka envisage the establishment of suitable fodder for livestock under irrigation programmes using brackish underground water. A study evaluated the response of three popular tropical grasses and the natural species to irrigation with brackish water having conductivities ranging from 0.5-6.0 ms. cm, when established in a sandy soil. The study was carried out for 6-7 months, with regular irrigation to correspond to the dry season. Growth of all three species was affected by increasing conductivity of water. Brachiaria mutica was affected to the greatest extent. Yields of Paspalum dilatatum were reduced to a lesser extent with increasing brackishness of water. Panicum maximum produced the highest yield and provided a significant quantity offodder in all treatments. However, the introduced species outyielded the natural species with the exception of Brachiaria at the higher levels of conductivity. The data illustrated the effect of brackishness on the yielding ability of the selected species. The practical significance of the study in terms ofpossible uses of these species in growing grasses under irrigation in the sandy tracts for herbage production in the dry season is presented

Response of french bean (Phaseolus vulgaris L.) to rate and ratio of potassium fertilizer application

A field study was undertaken to evaluate the effect of potassium fertilizer, when applied in different ratios, as a basal or top dressing on vegetative growth, immature pod and seed yield of French bean as well as seed quality for planting purpose determined by germination before and after controlled deterioration. The ratios of fertilizer application at a given rate of 100:0,50: or 0:100, were added at planting (basal) or at flowering (R1 stage - top dressing). Establishment of French bean was not affected by potassium. In contrast, vegetative growth and most yield components increased significantly with up to 100 kg K20 per ha. Application of a given rate only at planting (100:0) enhanced vegetative growth compared with a split rate. Application at flowering alone (0: 100) reduced all measured parameters, confirming the requirement of potassium at planting. Yields of immature pods harvested for vegetable purposes were not significantly increased by the two applications in the ratio of 50:50 (basal: top dressing). Seed quality determined by germination before and after controlled deterioration was also affected and split applications of 100 kg K20 in the ratio of 50:50 increased germinability

Influence of seed ripeness, sarcotesta, drying and storage on germinability of papaya (Carica papaya L.) seed

Papaya (Carica papaya L.) is a popular tropical fruit which is propagated by seed. However, germination and the procurement of good seedlings are difficult in this species due to the nature of the seed. Thus a series of studies to evaluate the influence of fruit maturity, sarcotesta and drying on germination and production of healthy seedlings was carried out. The characteristics of papaya seed change with fruit maturity. Speed of germination increases with fruit maturity. Thus, the best seed for germination and for the the procurement of healthy seedlings is obtained from ripe or over-ripe fruits. The presence of the sarcotesta reduces germination and increases the number of abnormal seedlings. Incorporation of the sarcotesta in the germination medium of papaya or rice seeds did not inhibit their germination. This suggests that inhibition is caused by the intact sarcotesta rather than inhibitors derived from it. Drying papaya seeds under shade and ambient temperature maintained germinability to a greater degree than when seeds were desiccated in ovens. The reduction of seed moisture below 10% reduced germination significantly, indicating an intermediate behaviour pattern for papaya seeds in contrast to orthodox or recalcitrant seeds

Crop diversification strategies for minor irrigation schemes: Proceedings of the workshop organized by the Irrigation Research Management Unit, Irrigation Department and the Sri Lanka National Program, International Irrigation Management Institute, held at the Irrigation Department, Colombo, Sri Lanka on 20 February 1996

Irrigation programs / Irrigation management / Small scale systems / Crops / Diversification / Rice / Cropping systems / Constraints / Social aspects / Economic aspects / Field crops / Crop production / Labor / Farmers' attitudes / Water management / Groundwater / Sri Lanka