Studies On The Mutation Effects Of Near-ground Space Treatment On Tomato

Tomato (Lycopersicum esculentum MILL.) belongs to Lycopersicon of Solanoideae. Its origin is in Peru and Ecuador in South America and is a main kind of vegetable in China. Germplasm resource is an important factor of tomato breeding. Tomato cultivar "HT10-3-2", obtained by space flight, was selected generation by generation, and their main agricultural characters and economic characters were observed in detail in order to contribute to tomato breeding and space mutation breeding. The main results were showed as follows:1 .The germinating rate and germinating energy were changed after tomato seeds were sent to space by recoverable satellite, but the extent of the change depended to the materials. After space flight, the flowering date was delayed, the variations among plants increased and the plants tended to be lower than CK. Space mutation had effects on the position of the 1st inflorescence, the number of flowers, the number of fruits, the size of fruits and so on. And the shape of leaves and the color of fruits were also changed.2.Space environment had great effects on tomato botany characters and agricultural characters. The results showed that, the growth energy of tomato was increased and some variations were heritable. For example, the average height of SP3 (from H1) and its offspring was 77.22⁸7.72% higher than that of CK, and they were all indeterminate growth habit. The average height of SP3 (from H3) and its offspring was 18.04²0.13% higher than that of CK and they were all determinate growth habit. The length of the greatest leaves in SP₄ (from H1-1) and SP₅ (from H-l-1) was 21.48-31.26% longer than that of CK. The shape of fruits had great changes in SP2. They changed from flat round to round, high round or round with a little flat.3.Space environment had obvious effects on the economic characters of tomato. After space mutation, the ability of fruiting, the weight of single fruit and the yield were increased, and it was possible to select a cultivar with bigger fruits and higher yield. The results showed that, the colony, with higher yield, also had stronger fruiting ability and its fruits were bigger, i.e. the yields of SP3, SP4 and SP5 (all from H2) were all 10% higher than that of CK. And their fruiting ability of the earliest three inflorescences were 30-75% higher than that of CK, the fruits average weight was 40% higher than that of CK. But the colony, with lower yield, had weaker fruiting ability and the fruits were smaller, i.e. the yields of SP4 and SP5 (from H3-2 and H3-2-1 respectively) were 18% lower than that of CK. And the average weight of single fruits was 20% lower than that of CK. To disease resistance,SP3 (from HI) had stronger ability to resist leaf mold.4.The characters obtained by space mutation were easier to be stable. The results showed that, the differences of the flowering dates of 1st inflorescence, the positions of 1st inflorescence, number of leaves between 1st and 2nd inflorescences in the colony were decreased with the development of generations. Most of these heritable characters could be stable in SP3 and a few could be stable in SP4, 2-3 generations earlier than that of traditional breeding (The characters were stable in 6 generations.).5.After space mutation, 6 kinds of varying characters were found in T10-3-2, and 2 fine cultivars were selected. Some characters were useful and some are useful. It showed that variations induced by space mutation were wide.