GROWTH, FRUIT YIELD AND QUALITY RESPONSES OF TWO VARIETIES OF TOMATO (Lycopersicum esculentum (L.) TO NITROGEN SOURCES AND ORGANIC MULCHES AT KADAWA, KANO STATE, NIGERIA

Abstract

Three field trials were conducted in the dry season of 2016, 2017 and 2018 at the Irrigation Research Farm of Institute for Agricultural Research, Kadawa (11039’ N 080’ 027’E, 500 m above sea level) located in the Sudan savanna ecological zone of Nigeria, to study the growth, fruit yield and quality responses of two irrigated varieties of tomato (Lycopersicum esculentum (L.) to nitrogen sources and organic mulches. Treatments consisted of two tomato varieties (UC82B and Rio Grande), two organic mulches (rice straw and sugar-cane peels) at recommended rates 5.5 t ha-1 and 11.0 t ha-1 (4 cm thick) respectively and a control (No mulch), and three nitrogen sources (mineral fertilizer, poultry droppings and mineral fertilizer + poultry droppings) at recommended rate of 90 kg N ha-1 with a control (No application). Varieties and nitrogen sources were assigned to the main plots while sugar-cane peels mulch was assigned to the sub plots and replicated three times. Results showed that Rio-Grande variety produced taller plants, wider canopy, high relative growth rate, net assimilation rate, low evapo-transpiration rate, longer days to 50% flowering and higher fruits yield of 57.89 % and marketable yield of 63.54 % over UC82B. Result from quality analysis has shown that the two varieties did not differ significantly (P≤0.05) from each other in all the quality traits evaluated. Tomato fruit qualities (appearance, decay, shelf life) as well as nutritional qualities were significantly enhanced by nitrogen sourced from organic sources than the unfertilised plots (control) while inorganic nitrogen sources contributed the least. Application of nitrogen sources showed that mineral fertilizer + poultry droppings showed superiority over poultry droppings and mineral fertilizer but did not differ significantly in their effect on growth and development. The growth and yield characters were significantly enhanced by organic mulching materials with rice straw and sugar cane peels showing a non significant difference compared to un-mulched plots. However, interaction of mineral fertilizer + poultry droppings in combination with any of the variety of tomato was significantly higher (P≤0.05) in enhancement of most of the growth and yield character but did not differ significantly with poultry droppings and mineral fertilizer in combination with any of the organic mulching materials with both varieties of tomato. Results from correlation and path analysis have shown that number of leaves gave the highest direct contributions in 2016 and 2017 while plant height gave the highest direct contribution in 2018. However, the highest individual percentage contribution was by plant height while the highest combined percentage contribution was by plant height via leaf area index. Cultural techniques capable of prompting the enhancement of characters such as number of leaves, canopy spread, plant dry weight and plant height should be considered with number of leaves playing the most important role and therefore should be given prominence. Cost and return analysis has indicated that poultry droppings (2.88 t ha-2) using sugar-cane peels mulch (11.0 t ha-1) with Rio-Grande gave the highest gross margin. Based on the results obtained from this study it can be concluded that Rio-Grande was superior to UC82B for higher fruit yield while for higher fruit quality any of the variety could be use. Poultry droppings at recommended rate (2.88 t ha-2) should be applied for increased growth, fruit yield and quality of tomato on sustainable bases. Sugar-cane peels mulch (11.0 t ha-1) is recommended as a suitable replacement to rice straw mulch.