Introduction. Root restriction occurs when seedlings are grown in increasingly small containers and it reduces plant growth in different ways. Therefore, the objectives of our study were to investigate the effects of varying container sizes and irrigation frequency on growth parameters of ‘Rough lemon’ (C. limon) plants Maseno, Kenya. Materials and methods. The treatments tested the effect of three container volumes (1.7 L, 2.7 L and 4.5 L) and three irrigation frequencies [every day (W1), every two days (W2) and every 3 days (W3)]. The design of the experiment was completely randomized with three replications. Growth parameters studied were plant height, canopy height, shoot and root weight, number of leaves and shoot to root ratio. Results and discussion. Increasing container volumes generally increased the height of plants, height of canopy, weight of whole plants and weight of roots, but it did not affect number of leaves, stem diameter or shoot to root ratio. Irrigation frequency increased number of leaves, height of plants, height of canopy, stem diameter and weight of shoots and roots, but this factor had no effect on weight of whole plants. These findings are explained by reduced root restriction in the largest container volumes. Conclusion. Increasing container volumes from 1.7 L to 4.5 L and irrigation frequency from every 3 days to every day increases plant growth as expressed in the various plant growth parameters.

Introduction. The determination of an adequate container volume that combines rational use of substrate with maximization of vegetative growth is very important to optimize citrus nursery tree production. This experiment aims to evaluate the influence of container volumes on vegetative growth of citrus nursery trees. Materials and Methods. Pera sweet orange nursery trees [Citrus sinensis (L.) Osbeck] budded on Rangpur lime (Citrus limonia Osbeck) were produced in six container volumes [(3.0, 3.8, 4.5, 4.6, 5.0 and 5.8) L], with the respective container dimensions of [(20 × 32, 20 × 35, 22 × 32, 22.5 × 35, 25 × 32 and 25 × 35) cm]. Another 5.0-L container studied had the dimensions of 20 cm x 40 cm. Commercial substrate was composed of Pinus bark and a controlled-release fertilizer was used. Parameter evaluation started after moving the rootstocks from seedling trays, 3.5 months after sowing, to plastic containers and continued until nursery trees reached one year old. The studied parameters were shoot height, diameter and leaf area of rootstocks and nursery trees, bud take percentage and scion and root dry matter of nursery trees. Results and discussion. The development of Rangpur lime plants was not affected by any treatment until budding. The largest container volumes induced faster and more vigorous vegetative development of Pera sweet orange nursery trees budded on Rangpur lime. A 5.0-L container volume could be indicated as a technical and economical option for the production of containerized citrus nursery trees.