MSc

The project entitled “Evaluation of tomato (Solanum lycopersicum L.)
hybrids for yield and bacterial wilt resistance” was carried out at the department
of Olericulture, College of Agriculture, Vellayani, during 2015-2017 to identify
tomato hybrids with high yield, quality and resistance to bacterial wilt.
The experiment was carried out in two parts. In part I, F1 seeds of the eight
superior hybrids with respect to bacterial wilt resistance and yield selected based
on specific combining ability and per se performance identified in the previous M.
Sc programme were produced in a crossing block during May - August 2016. In
part II, the hybrids along with two standard checks- one resistant (Jessica) and one
susceptible (Naveen) were evaluated for yield and bacterial wilt resistance. Two
separate experiments were conducted- one under field condition (Randomized
Block Design) and another under artificial epiphytotic conditions (inoculated trial
in pots) (Completely Randomized Design) from October 2016 –January 2017 with
10 treatments and 3 replications.
The results of the field experiment showed significant difference among
the treatments for all traits studied. Plant height was highest in Naveen (102.39
cm), while the cross LE 20 × Manulekshmi recorded highest number of primary
branches plant-1 (11.60). Leaf length was highest in LE 13 × Manulekshmi (34.81
cm) and leaf width in Naveen (22.58 cm).
LE 13 × Vellayani Vijai recorded lowest node to inflorescence (9.87);
earliest flowering (20.33 days) was noted in LE 16 × Vellayani Vijai, while days
to fruit set was lowest in LE 13 × Manulekshmi (6.67). Highest flowers cluster-1
(8.27) was recorded in LE 13 × Vellayani Vijai; inflorescence plant-1 and fruits
plant-1 was maximum in LE 16 × Anagha (36.27 and 90.47 respectively) and
maximum fruits truss-1 and fruit set percent was recorded by LE 16 × Vellayani
Vijai (4.73 and 83.19 respectively).
Jessica recorded maximum fruit length, fruit diameter and fruit weight
(6.28 cm, 5.49 cm, 99.48 g respectively). Among the crosses LE 20 ×
Manulekshmi recorded highest fruit weight (67.82 g). Highest yield plant-1 was
recorded by LE 20 × Manulekshmi (1836 g) followed by LE 16 × Manulekshmi
(1773 g) and highest yield plot-1 was recorded by LE 20 × Manulekshmi (26.72
kg) followed by LE 16 × Vellayani Vijai (23.74 kg). With respect to quality
characters, LE 16 × Vellayani Vijai recorded highest TSS (4.69 %) followed by
LE 16 × Manulekshmi (4.03%). Lycopene was highest in LE 13 × Vellayani Vijai
(12.99 μg g-1), ascorbic acid in LE 19 × Anagha (30.22 mg 100g-1).
Bacterial population (Ralstonia solanacearum) in the experimental field
was assessed three times. It was 1.75×105 cfu g-1 before planting, 1.17×105 cfu g-1
during crop period and 5.53×105 cfu g-1 at last harvest. None of the hybrids except
Naveen exhibited the disease symptoms, which depicted the field resistance.
Correlation analysis revealed that yield plant-1 was positively correlated
with primary branches plant-1, inflorescence plant-1, fruit set percent, fruits plant-1
and fruits truss-1, and negatively correlated with days to first flowering, lycopene,
TSS and plant height.
Artificial inoculation studies revealed significant difference among
treatments for percent disease incidence at a bacterial concentration of 105 cfu ml-1
as inoculum. It was lowest in LE 16 × Vellayani Vijai and resistant check
(26.67%) whereas incidence was 100 per cent in the susceptible check.
LE 20 × Manulekshmi was adjudged as the best hybrid considering yield
plant-1, yield plot-1, fruit size and field resistance to bacterial wilt. For bacterial
wilt resistance, LE 16 × Vellayani Vijai was the best based on both field trial and
inoculated trial.