Category Archives: Volume 5 No. 2 (1983)

Effects of Flooding on Seven Species of Tropical Pasture Legumes


Author: Reynaldo R. Javier

Abstract

Seven tropical pasture legume species were grown in pots inside the glass-house. At the start of flowering stage, plants were continuously flooded to 5 cm above the soil surface for 10 and 21 days. Dry weights of shoots, roots and no-dules of the flooded plants were compared to the corresponding unflooded plants after a recovery period of 7 days. Macroptilium lathyroides exhibited superior tolerance to flooding while Cassia rotundifolia and Vigna parkeri showed very poor tolerance.
Root growth was more affected by flooding than shoot growth. Modulation was reduced in all species except in M. lathyroides. The adaptation of M. lathyroides, Desmodium heterophyllum, Lotononis bainesii and Trifolium semi-pilosum to flooding was related to the rapid production of adventitious roots from the immersed stems and branches and to the rapid nodulation of these adventitious roots and the original roots.
High stomatal conductance was maintained in flood-tolerant species with increased duration of flooding while high leaf diffusive resistance was common in species intolerant to flooding.

Keywords : Pasture legumes. Flooding tolerance. Plant survival. Adventi-tious roots. Nodulation.

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Effect of Row Spacing and Time of Weeding on the Growth and Yield of [Vigna radiate (L.) Wilzeck]


Author: Benjamin C. Agarcio, Jr.

Abstract

A field experiment was conducted to evaluate the effect of row spacing and time of weeding on the competitiveness of mungbean against weeds.
Dry weed weight was generally higher at wider row spacing than at closer spacing because of more space available for weed growth.
Controlling weeds in mungbean within the first 4 weeks after seeding re-sulted in optimum yield. Weeds that emerged beyond 4 weeks after seeding were shaded out by the mungbean canopy and did not considerably reduce grain yield.
It appears that 2 timely weedings during the period of critical competition in mungbean could result in optimum yield comparable to that which can be obtained from season-long weeding.

Keywords : Mungbean (Vigna radiata (L.) Wilzeck). Weeds. Row spacing. Time of weeding. Weed competition.

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Cytological Effects of Fungicide Bavistin on the Root Meristem of Coffee


Author(s): R.K. Somashekar, Siddaramaiah, K.P. Srinath and P. Venkatasubbaiah

Abstract

Bavistin, a systemic fungicide, was tested for its mitodepressive and antimitotic effect on coffee (Coffea arabica L.). A drastic reduction in the mitotic index occurred as the concentration and duration of treatment increased. Bavistin also influenced the frequency of mitotic phases and behaved as a potential clastogenic and turbagenic agent. The fungicide induced spindle abnormalities leading to the occurrence of C-metaphase, binucleate cells and cells with bridges, breaks, laggards and micronuclei. The recommended dosage of 0.05% was found to be quite unsafe in the present study, since this fungicide produced various forms of cell abnormalities.

Keywords : Bavistin. Mitotic effect. Coffee. Spindle abnormalities. Chromosome aberrations.

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Mycorrhiza- A Possible Adaptive Mechanism of Sweet Potato in Marginal Soils


Author: Gloria L. Tupas

Abstract

Root samples of sweet potato were examined for possible microbial association. Examination of roots from relatively open marginal soils exhibited evidence of mycorrhizal infection particularly the vesicular-arbuscular type. The capability of sweet potato for mycorrhizal association could be one of its adaptations for growth and productivity in marginal soils.

Keywords : Sweet potato. Marginal conditions. Mycorrhiza association. Benefits.

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Effect of Storage of Decomposition of Green Manure on the Growth and Yield of Sweet Potato


Author(s): Pablito L. Sevenorio and Rodolfo G. Escalada

Abstract

The use of either soybean or mungo as green manure crop did not significantly affect the agronomic characters, yield and yield components of sweet potato except the number of marketable tubers. Stage of green manure decomposition greatly influenced vine length and leaf area index during the second and third months of sweet potato growth including the length and diameter of tubers, weight and number of marketable tubers/ha, total tuber yield, and harvest index. No significant effects on fresh and dry weights of vines as well as number and weight of non-marketable tubers were noted. Higher yield was obtained when sweet potato was planted 21 days after soybean residue had been plowed under the soil.

Keywords : Green manure. Stage of decomposition. Agronomic characters. Harvest index

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Growth and Partitioning in Sweet Potatoes


Author(s): John C. Bouwkamp

Abstract

In 4 sweet potato cultivars studied, harvest indices and dry weight accumulations of sweet potato storage roots and total plant dry weight increased throughout the growing season, but declined during the later part of the season. Vine dry weight slowly increased reaching a maximum at 14-16 weeks after transplanting, then slowly decreased throughout the season except in 1 cultivar where vine weight continued to increase. It is suggested that a balance between vines and roots is a factor in obtaining maximum yield, and that the crop may be either sink or source limited if a suitable balance is not maintained.

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