Journal of Arid Environments (1995) 29:169-172

Effect of seed size on developmental traits and ability to tolerate drought in pearl millet

V. K. Manga & O. P. Y a d a v

Central Arid Zone Research Institute, Jodhpur-342 003, India

(Received 24 February 1993, accepted 17July 1993)

Seeds of seven genotypes were graded into small and large sizes to study the influence of seed size on the field performance of pearl millet (Pennisetum glaucum) under moisture stress conditions. Analysis of variance revealed that both seed size and genotypes significantly influenced early vigour, number of tillers per plant, plant height, days to wilting initiation, days to permanent wilting and dry matter production. Larger seeds in general produced vigorous seedlings, taller plants with greater tillering and higher levels of dry matter. Plants from larger seeds took longer to initiate wilting and then permanent wilting compared with plants from smaller seeds. An association study revealed that the weight of 1000 grains significantly and positively correlated with all traits studied except plant height. To improve the performance of pearl millet under arid conditions, conditioning of the seed lots for seed size is suggested.

Keywords: Pennisetum glaucum; pearl millet; drought tolerance; early vigour; seed size

Introduction

Pearl millet (Pennisetum glaucum (L.) R. Br.), which forms the staple diet for 10% of Indian population, is generally grown as a rainfed crop in the arid and semi-arid regions of the country. Owing to low and erratic rainfall in these regions, this crop faces moisture stress at various stages of its development. Despite the development of high yielding cultivars, this crop suffers from low productivity primarily because of drought. In the present study an attempt has been made to determine if grading pearl millet seed for seed size would improve its growth and ability to tolerate drought.

Materials and methods

Seeds of seven pearl millet genotypes viz., M 78, SPTC 412, VNo. 2 local, BJ 104, TR 50, DT-2 and Pb 111A, were graded into large and small sized seed lots by sieving. Seeds from an ungraded seed lot that were retained by a 2"4 mm mesh were kept as large seeds. Seeds that passed through a 2"0 mm mesh but were retained by a 1"8 mm mesh were kept as small seeds. Thousand-grain weight of the three categories, i.e. large, ungraded and small was also recorded (Table 1).

Address for correspondence: V. K. Manga, Division-Ill, Central Arid Zone Research Institute, Jodhpur- 342 003, Rajasthan, India.

0140-1963/95/020169 + 04 $08"00/0 (~) 1995 Academic Press Limited

Table 1. lO00-grain weight (g) of different categories of seeds of pearl millet

Seed size

o

o O3

Genotype Large Ungraded Small

M 78 11" 12 8"08 5"48 SPTC412 11"36 10-00 6"75 VNo. 2 Local 10"60 7"18 5"42 BJ 104 7"24 6"22 5"02 TR 50 10"26 8"60 4"90 DT-2 10"00 7"76 5"02 Pb I 11A 7"46 6"40 5"86

The experiment was conducted during a rainfree period (March - May, 1985) at the Central Arid Zone Research Institute, Jodhpur in a field of sandy-loam soil. The experimental plot was irrigated and then ploughed to provide a fine tilth and levelled seed beds were prepared. The experiment was laid out in a split-plot design with three replications. Varieties were kept as main plots with seed size as sub-plots. Seeds were dibbled in moist beds at 15 cm intervals, in 3 m rows, spaced 50 cm apart. Two weeks after sowing a light irrigation was administered and the crop then allowed to grow under decreasing soil moisture conditions (Fig. 1) until it showed permanent wilting and dried up. During the experiment seedlings were arbitrarily scored 15 days after germination for

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2

170 V. K. M ANGA & O. P. YADAV

I I I I I I 5 10 15 20 25 30

Days a f te r i r r iga t ion

Figure 1. Moisture content in soil profile (60 cm).

35

EFFECT OF SEED SIZE IN PEARL MILLET

Table 2. Analysis of variance for various traits in pearl millet

171

Source

Mean squares

Dry Tillers/ Early Plant df. matter plant vigour height DWIt DPW~:

Replications Genotypes Error (a) Seed size Genotype x

seed size Error (b)

2 0'19 5"30 0"59 72-68* 6 73-24** 4"93 1"76"* 2946"3**

12 6'76 2"08 0"44 14"26 2 721"59"* 25"67** 4"49** 1539"70"*

12 20"88* 0"76 0"35 132"58"*

28 9-85 1'41 0"198 38"96

2"71 14"47 5'67

28"62** 2"30

2"44

31"35 63-93* 13"27 70"30**

3"62

2"62

* Significant a t p = 0"05. ** Significant a t p = 0"01. t DW I = Days to wilting initiation. :~ DP W = Days to permanant wilting.

early vigour using a 1 (poor) to 5 (excellent) scale. Data were also recorded for days to wilting initiation, days to permanent wilting, basal tillers per plant, plant height (cm) at harvest and dry matter per plant (g).

Results and discussions

Analysis of variance (Table 2) revealed that significant differences existed among pearl millet genotypes for early vigour, plant height, days to permanent wilting and dry matter yield. This showed the possibility of being able to select genotypes having vigorous growth and tolerance to drought in terms of delayed wilting. Significant variability for early vigour had earlier been reported by Singh et al. (1982) and Manga & Saxena (1990). Highly significant mean squares due to seed size indicated that seeds of different size significantly influenced the expression of these traits. Significant seed size x genotype interactions were observed for dry matter yield and plant height, while such interactions were not significant for the other traits (Table 2). This showed inconsistent responses from the different seed sizes of the various varieties to dry matter yield and plant height, and consistent contribution over genotypes by each type of seed size to early vigour, filler numbers, days to wilting initiation and days to permanent wilting.

Mean values over varieties for the various traits are presented in Table 3. Larger seeds produced vigorous seedlings with an average early vigour score of 4"04 compared with 3" 14

Table 3. Mean values of various traits for different seed sizes in pearl millet

Dry Plant matter Tillers/ Early height

Seed size (g) plant vigour (cm) DWI * DPWt

Large 21 "63 7"95 4"04 76"57 32"04 44"33 Ungraded 18"01 6"65 3"42 67" 14 30"80 43"23 Small 10" 16 5"75 3" 14 59"47 29"66 40"76 CD _+ o-05 1 "98 0"75 0"28 3"94 0"98 1"02

* D W I = Days to wilting initiation. t DP W = Days to permanant wilting.

172 V. K. MANGA & O. P. YADAV

Table 4. Inter-relationships among various traits in pearl millet

Seed Early Tillers/ Plant Dry Character weight vigour plant height DWIt DPW1: matter

Seed weight 1"00 0"74** 0"50* 0"32 0"65** 0"57** 0"69** Early vigour 1"00 0"33 0"30 0"63** 0"65** 0"65** Tillers/plant I'00 0"69** 0"67** 0"29 0"46* Plant height 1"00 0"74** 0"35 0"33 DWI 1"00 0"59** 0"56** DPW 1"00 0"69** Dry matter 1"00

* Signif icant at p = 0"05. ** Signif icant at p = 0 '01. "1" D W I = Days to wi l t ing i n i d a d o n . :~ D P W = Days to p e r m a n a n t wi l t ing .

for seedlings from small seeds, and 20" 1% and 112"8% more dry matter than ungraded and small seed lots respectively.

According to Kaufmann & Guitard (1967), larger seeds produced vigorous seedlings because they provide more carbohydrate reserves for the growing seedlings and the initial advantage in terms of vigorous seedlings results in better expression of other plant traits. Furthermore, the larger seeds produced taller plants with a greater number of tillers and took longer for wilting initiation and permanent wilting to occur under increasing soil moisture stress. This emphasized the importance of having bold-seeded varieties for arid regions. The advantage of larger seeds in low yielding moisture stress conditions has also been emphasized by Gardner & Vanderlip (1989).

A number of simple correlations were worked out between 1000-grain weight and other traits to establish further the effect of seed size on various developmental traits (Table 4). The study revealed that the 1000-grain weight was positively correlated with all traits except plant height. The highest degree of association of the 1000-grain weight was observed with early vigour (r = 0"74) followed by dry matter yield (r = 0"69) and days to wilting initiation (r = 0"65). A study of inter-relationship among the other traits revealed that early vigour had a positive association with days to wilting initiation, days to permanent wilting and dry matter production. This emphasized the importance of vigorous genotypes capable of tolerating drought for longer periods. The importance of having vigorous genotypes for growing under drought conditions has been stressed previously by Manga & Saxena (1990).

This study demonstrated that large seed size led to vigorous seedlings and taller plants with increased tillering and drought tolerance. Thus, by simply improving the seed lot for seed size it should be possible to improve the field performance of the pearl millet genotypes under the moisture deficit conditions that occur in arid western Rajasthan.

References

Gardner, J. C. & Vanderlip, R. L. (1989). Seed size and density effects on field performance of pearl millet. Transactions of Kansas Academy of Science, 92: 49-59.

Kaufmarm, M. L. & Guitard, A. A. (1967). The effect of seed size on early plant development in barley. Canadian Journal of Plant Science, 47: 73-78.

Manga, V. K. & Saxena, M. B. L. (1990). Variability for seedling vigour and its association with yield in pearl millet. Crop Improvement, 17: 83-84.

Singh, J. N., Pokhriyal, S. C., Murty, B. R. & Doshi, S. P. (1982). Combining ability of downy mildew resistant lines of pearl millet. Indian Journal of Genetics and Plant Breeding, 42: 200-203.