Subsequent Crop Performance Research Articles

555 The Impact of Supplemental Calcium Fertilization during Potato Seed Tuber Production on Subsequent Crop Performance

Tuber tissue calcium has been linked to several potato quality characteristics, including internal defects and the susceptibility of tubers to decay by soft rotting Erwinia species. We were particularly interested in studying the relationship between supplemental calcium fertilization during the seed tuber production cycle to raise the seed piece calcium concentration and the impact on crop performance the following season. The role of seed tuber tissue calcium level on seed piece decay, growth, development, and performance of the plant was evaluated for cultivars Russet Burbank, Dark Red Norland, Atlantic, Superior, and Snowden. This study was performed over four growing seasons. Seed tubers were raised with varying calcium and the following season, individual tubers (over 3,000 total for 4 years of study) were sampled for calcium and hand planted in the field. They were evaluated for seed piece decay and total tuber yield during the growing season. Seed tubers raised with supplemental calcium resulted in significantly higher mean calcium content than the control tubers. In general, calcium-raised seed tubers tended to produce a more vigorous main sprout and higher tuber yield. We also found that there are significant differences among these cultivars for the characteristics measured. Consistently, in all three years, `Atlantic' responded to test conditions with the lowest decay values, and `Dark Red Norland' consistently showed the highest decay values. This suggests that there may be a genetic component involved in these two responses and these genotypic differences could be exploited to improve cultivated potatoes.

Comparative performance of potato crops raised from microtubers induced in the dark versus microtubers induced in light

The performance of potato crops raised from two types of microtuber, green (induced in light-dark photoperiod) and white (induced in continuous darkness), of 18 genotypes was studied for 22 morphological and agronomic characters. Mean squares due to microtuber type, genotype and their interaction were mostly significant for various characters. Green microtubers were better than white microtubers for subsequent crop performance for most of the characters including tuber yield and general impression. This was mainly due to more eyes and shorter dormancy in green microtubers than in white microtubers. The in vitro system of microtuberization by serial culture of axillary buds in separated nodes, as used in the present study, was found to be genetically stable for the propagating material.

Tillage methods and soil and water conservation in eastern Africa

This paper reviews some research studies on tillage methods influencing soil and moisture conservation in the eastern African countries of Kenya, Tanzania, Malawi and Ethiopia during the past four decades. Most of these studies were conducted in marginal rainfall (semi arid) areas and on shallow soils of various textures (sandy clay loam, sandy clay, clay and loam). The studies were meant to establish the effects of tillage and residue management practices on physico-chemical soil properties (i.e. structure, bulk density, soil moisture and organic matter contents), runoff and infiltration. This review emphasizes the importance of appropriate tillage and residue management methods (contour bunds and terraces, minimum tillage, tied ridging, mulching and conventional tillage) in providing soil conditions favourable for soil moisture conservation and subsequent crop performance and yield on smallholder farms.

Field Criteria Used in Determining the Vigor of Seed Corn (Zea mays L.) as Influenced by Drying Injury

AbstractGeneral agreement does not exist regarding the influence of seed corn (Zea mays L.) vigor on subsequent crop performance. Studies were conducted to determine the characters through which seed corn vigor is expressed, how long the influence persists and the relationship among the characters identified. Seeds of two corn hybrids A632 X (H99 X H95) and B73 X (H99 X H95), dried at 35 °C and 50 °C were grown in the field in each of 2 years and in the growth chamber in Ames, Iowa. A complete range of growth parameters was measured in the laboratory and growth chamber and field. Of these parameters, emergence, emergence rate, plant height, stem diameter, shoot dry matter at 4 and 6 weeks and penultimate leaf length and width were characters found to be influenced by seed vigor. As the plants matured, the influence of seed vigor decreased. Positive and negative relationships were found to exist between some of the characters influenced by seed vigor. However, seed vigor had no influence on yield.